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* [PATCH 0/1] block, bfq: remove bfq prefix from cgroups filenames
@ 2019-09-09  7:31 Paolo Valente
  2019-09-09  7:31 ` [PATCH 1/1] block, bfq: delete "bfq" prefix from cgroup filenames Paolo Valente
  2019-09-16 14:56 ` [PATCH 0/1] block, bfq: remove bfq prefix from cgroups filenames Paolo Valente
  0 siblings, 2 replies; 25+ messages in thread
From: Paolo Valente @ 2019-09-09  7:31 UTC (permalink / raw)
  To: Jens Axboe
  Cc: linux-block, linux-kernel, ulf.hansson, linus.walleij,
	bfq-iosched, oleksandr, Tejun Heo, cgroups, Paolo Valente

Hi Jens,
now that BFQ's weight interface has been fixed [1], can we proceed
with this change?

In addition to acking this solution, in [2] Tejun already suggested a
reduced version of the present patch. In Tejun's version, only
bfq.weight is changed. But I guess that legacy code may use also some
of the other bfq parameters in cgroups, without the bfq prefix. Apart
from that, any version is ok for me, provided that it solves the
current confusing situation for userspace [3].

Thanks,
Paolo

[1] https://lkml.org/lkml/2019/8/27/1716
[2] https://www.mail-archive.com/linux-block@vger.kernel.org/msg35823.html
[3] https://github.com/systemd/systemd/issues/7057

Angelo Ruocco (1):
  block, bfq: delete "bfq" prefix from cgroup filenames

 block/bfq-cgroup.c | 46 +++++++++++++++++++++++-----------------------
 1 file changed, 23 insertions(+), 23 deletions(-)

--
2.20.1

^ permalink raw reply	[flat|nested] 25+ messages in thread

* [PATCH 1/1] block, bfq: delete "bfq" prefix from cgroup filenames
  2019-09-09  7:31 [PATCH 0/1] block, bfq: remove bfq prefix from cgroups filenames Paolo Valente
@ 2019-09-09  7:31 ` Paolo Valente
  2019-09-16 14:56 ` [PATCH 0/1] block, bfq: remove bfq prefix from cgroups filenames Paolo Valente
  1 sibling, 0 replies; 25+ messages in thread
From: Paolo Valente @ 2019-09-09  7:31 UTC (permalink / raw)
  To: Jens Axboe
  Cc: linux-block, linux-kernel, ulf.hansson, linus.walleij,
	bfq-iosched, oleksandr, Tejun Heo, cgroups, Angelo Ruocco,
	Paolo Valente

From: Angelo Ruocco <angeloruocco90@gmail.com>

When bfq was merged into mainline, there were two I/O schedulers that
implemented the proportional-share policy: bfq for blk-mq and cfq for
legacy blk. bfq's interface files in the blkio/io controller have the
same names as cfq. But the cgroups interface doesn't allow two
entities to use the same name for their files, so for bfq we had to
prepend the "bfq" prefix to each of its files. However no legacy code
uses these modified file names. This naming also causes confusion, as,
e.g., in [1].

Now cfq has gone with legacy blk, so there is no need any longer for
these prefixes in (the never used) bfq names. In view of this fact, this
commit removes these prefixes, thereby enabling legacy code to truly
use the proportional share policy in blk-mq.

[1] https://github.com/systemd/systemd/issues/7057

Signed-off-by: Angelo Ruocco <angeloruocco90@gmail.com>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
---
 block/bfq-cgroup.c | 46 +++++++++++++++++++++++-----------------------
 1 file changed, 23 insertions(+), 23 deletions(-)

diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c
index 0f6cd688924f..14b7a1160664 100644
--- a/block/bfq-cgroup.c
+++ b/block/bfq-cgroup.c
@@ -1139,7 +1139,7 @@ struct blkcg_policy blkcg_policy_bfq = {
 
 struct cftype bfq_blkcg_legacy_files[] = {
 	{
-		.name = "bfq.weight",
+		.name = "weight",
 		.flags = CFTYPE_NOT_ON_ROOT,
 		.seq_show = bfq_io_show_weight,
 		.write_u64 = bfq_io_set_weight_legacy,
@@ -1147,42 +1147,42 @@ struct cftype bfq_blkcg_legacy_files[] = {
 
 	/* statistics, covers only the tasks in the bfqg */
 	{
-		.name = "bfq.io_service_bytes",
+		.name = "io_service_bytes",
 		.private = (unsigned long)&blkcg_policy_bfq,
 		.seq_show = blkg_print_stat_bytes,
 	},
 	{
-		.name = "bfq.io_serviced",
+		.name = "io_serviced",
 		.private = (unsigned long)&blkcg_policy_bfq,
 		.seq_show = blkg_print_stat_ios,
 	},
 #ifdef CONFIG_BFQ_CGROUP_DEBUG
 	{
-		.name = "bfq.time",
+		.name = "time",
 		.private = offsetof(struct bfq_group, stats.time),
 		.seq_show = bfqg_print_stat,
 	},
 	{
-		.name = "bfq.sectors",
+		.name = "sectors",
 		.seq_show = bfqg_print_stat_sectors,
 	},
 	{
-		.name = "bfq.io_service_time",
+		.name = "io_service_time",
 		.private = offsetof(struct bfq_group, stats.service_time),
 		.seq_show = bfqg_print_rwstat,
 	},
 	{
-		.name = "bfq.io_wait_time",
+		.name = "io_wait_time",
 		.private = offsetof(struct bfq_group, stats.wait_time),
 		.seq_show = bfqg_print_rwstat,
 	},
 	{
-		.name = "bfq.io_merged",
+		.name = "io_merged",
 		.private = offsetof(struct bfq_group, stats.merged),
 		.seq_show = bfqg_print_rwstat,
 	},
 	{
-		.name = "bfq.io_queued",
+		.name = "io_queued",
 		.private = offsetof(struct bfq_group, stats.queued),
 		.seq_show = bfqg_print_rwstat,
 	},
@@ -1190,66 +1190,66 @@ struct cftype bfq_blkcg_legacy_files[] = {
 
 	/* the same statistics which cover the bfqg and its descendants */
 	{
-		.name = "bfq.io_service_bytes_recursive",
+		.name = "io_service_bytes_recursive",
 		.private = (unsigned long)&blkcg_policy_bfq,
 		.seq_show = blkg_print_stat_bytes_recursive,
 	},
 	{
-		.name = "bfq.io_serviced_recursive",
+		.name = "io_serviced_recursive",
 		.private = (unsigned long)&blkcg_policy_bfq,
 		.seq_show = blkg_print_stat_ios_recursive,
 	},
 #ifdef CONFIG_BFQ_CGROUP_DEBUG
 	{
-		.name = "bfq.time_recursive",
+		.name = "time_recursive",
 		.private = offsetof(struct bfq_group, stats.time),
 		.seq_show = bfqg_print_stat_recursive,
 	},
 	{
-		.name = "bfq.sectors_recursive",
+		.name = "sectors_recursive",
 		.seq_show = bfqg_print_stat_sectors_recursive,
 	},
 	{
-		.name = "bfq.io_service_time_recursive",
+		.name = "io_service_time_recursive",
 		.private = offsetof(struct bfq_group, stats.service_time),
 		.seq_show = bfqg_print_rwstat_recursive,
 	},
 	{
-		.name = "bfq.io_wait_time_recursive",
+		.name = "io_wait_time_recursive",
 		.private = offsetof(struct bfq_group, stats.wait_time),
 		.seq_show = bfqg_print_rwstat_recursive,
 	},
 	{
-		.name = "bfq.io_merged_recursive",
+		.name = "io_merged_recursive",
 		.private = offsetof(struct bfq_group, stats.merged),
 		.seq_show = bfqg_print_rwstat_recursive,
 	},
 	{
-		.name = "bfq.io_queued_recursive",
+		.name = "io_queued_recursive",
 		.private = offsetof(struct bfq_group, stats.queued),
 		.seq_show = bfqg_print_rwstat_recursive,
 	},
 	{
-		.name = "bfq.avg_queue_size",
+		.name = "avg_queue_size",
 		.seq_show = bfqg_print_avg_queue_size,
 	},
 	{
-		.name = "bfq.group_wait_time",
+		.name = "group_wait_time",
 		.private = offsetof(struct bfq_group, stats.group_wait_time),
 		.seq_show = bfqg_print_stat,
 	},
 	{
-		.name = "bfq.idle_time",
+		.name = "idle_time",
 		.private = offsetof(struct bfq_group, stats.idle_time),
 		.seq_show = bfqg_print_stat,
 	},
 	{
-		.name = "bfq.empty_time",
+		.name = "empty_time",
 		.private = offsetof(struct bfq_group, stats.empty_time),
 		.seq_show = bfqg_print_stat,
 	},
 	{
-		.name = "bfq.dequeue",
+		.name = "dequeue",
 		.private = offsetof(struct bfq_group, stats.dequeue),
 		.seq_show = bfqg_print_stat,
 	},
@@ -1259,7 +1259,7 @@ struct cftype bfq_blkcg_legacy_files[] = {
 
 struct cftype bfq_blkg_files[] = {
 	{
-		.name = "bfq.weight",
+		.name = "weight",
 		.flags = CFTYPE_NOT_ON_ROOT,
 		.seq_show = bfq_io_show_weight,
 		.write = bfq_io_set_weight,
-- 
2.20.1


^ permalink raw reply	[flat|nested] 25+ messages in thread

* Re: [PATCH 0/1] block, bfq: remove bfq prefix from cgroups filenames
  2019-09-09  7:31 [PATCH 0/1] block, bfq: remove bfq prefix from cgroups filenames Paolo Valente
  2019-09-09  7:31 ` [PATCH 1/1] block, bfq: delete "bfq" prefix from cgroup filenames Paolo Valente
@ 2019-09-16 14:56 ` Paolo Valente
  2019-09-16 15:01   ` Jens Axboe
  1 sibling, 1 reply; 25+ messages in thread
From: Paolo Valente @ 2019-09-16 14:56 UTC (permalink / raw)
  To: Jens Axboe
  Cc: linux-block, linux-kernel, Ulf Hansson, Linus Walleij,
	noreply-spamdigest via bfq-iosched, oleksandr, Tejun Heo,
	cgroups

News of this change?  Can we have it (or the solution with the
symlinks if you prefer it) for 5.4?

Thanks,
Paolo

> Il giorno 9 set 2019, alle ore 09:31, Paolo Valente <paolo.valente@linaro.org> ha scritto:
> 
> Hi Jens,
> now that BFQ's weight interface has been fixed [1], can we proceed
> with this change?
> 
> In addition to acking this solution, in [2] Tejun already suggested a
> reduced version of the present patch. In Tejun's version, only
> bfq.weight is changed. But I guess that legacy code may use also some
> of the other bfq parameters in cgroups, without the bfq prefix. Apart
> from that, any version is ok for me, provided that it solves the
> current confusing situation for userspace [3].
> 
> Thanks,
> Paolo
> 
> [1] https://lkml.org/lkml/2019/8/27/1716
> [2] https://www.mail-archive.com/linux-block@vger.kernel.org/msg35823.html
> [3] https://github.com/systemd/systemd/issues/7057
> 
> Angelo Ruocco (1):
>  block, bfq: delete "bfq" prefix from cgroup filenames
> 
> block/bfq-cgroup.c | 46 +++++++++++++++++++++++-----------------------
> 1 file changed, 23 insertions(+), 23 deletions(-)
> 
> --
> 2.20.1


^ permalink raw reply	[flat|nested] 25+ messages in thread

* Re: [PATCH 0/1] block, bfq: remove bfq prefix from cgroups filenames
  2019-09-16 14:56 ` [PATCH 0/1] block, bfq: remove bfq prefix from cgroups filenames Paolo Valente
@ 2019-09-16 15:01   ` Jens Axboe
  2019-09-16 15:07     ` Paolo Valente
  0 siblings, 1 reply; 25+ messages in thread
From: Jens Axboe @ 2019-09-16 15:01 UTC (permalink / raw)
  To: Paolo Valente
  Cc: linux-block, linux-kernel, Ulf Hansson, Linus Walleij,
	noreply-spamdigest via bfq-iosched, oleksandr, Tejun Heo,
	cgroups

On 9/16/19 8:56 AM, Paolo Valente wrote:
> News of this change?  Can we have it (or the solution with the
> symlinks if you prefer it) for 5.4?

Coordinate with Tejun and bundle the stuff we need into a series, we
can definitely put that in 5.4. I did send out the initial pull request
for block, but I've got a few things lined up for a secondary pull
later this week.

-- 
Jens Axboe


^ permalink raw reply	[flat|nested] 25+ messages in thread

* Re: [PATCH 0/1] block, bfq: remove bfq prefix from cgroups filenames
  2019-09-16 15:01   ` Jens Axboe
@ 2019-09-16 15:07     ` Paolo Valente
  2019-09-16 15:16       ` Tejun Heo
  0 siblings, 1 reply; 25+ messages in thread
From: Paolo Valente @ 2019-09-16 15:07 UTC (permalink / raw)
  To: Jens Axboe, Tejun Heo
  Cc: linux-block, linux-kernel, Ulf Hansson, Linus Walleij,
	noreply-spamdigest via bfq-iosched, Oleksandr Natalenko, cgroups



> Il giorno 16 set 2019, alle ore 17:01, Jens Axboe <axboe@kernel.dk> ha scritto:
> 
> On 9/16/19 8:56 AM, Paolo Valente wrote:
>> News of this change?  Can we have it (or the solution with the
>> symlinks if you prefer it) for 5.4?
> 
> Coordinate with Tejun and bundle the stuff we need into a series,

Ok.

Tejun, could you put your switch-off-io-cost code into a standalone
patch, so that I can put it together with this one in a complete
series?

Thanks,
Paolo


> we
> can definitely put that in 5.4. I did send out the initial pull request
> for block, but I've got a few things lined up for a secondary pull
> later this week.
> 
> -- 
> Jens Axboe
> 


^ permalink raw reply	[flat|nested] 25+ messages in thread

* Re: [PATCH 0/1] block, bfq: remove bfq prefix from cgroups filenames
  2019-09-16 15:07     ` Paolo Valente
@ 2019-09-16 15:16       ` Tejun Heo
  2019-09-16 15:21         ` Paolo Valente
  0 siblings, 1 reply; 25+ messages in thread
From: Tejun Heo @ 2019-09-16 15:16 UTC (permalink / raw)
  To: Paolo Valente
  Cc: Jens Axboe, linux-block, linux-kernel, Ulf Hansson,
	Linus Walleij, noreply-spamdigest via bfq-iosched,
	Oleksandr Natalenko, cgroups

Hello, Paolo.

On Mon, Sep 16, 2019 at 05:07:29PM +0200, Paolo Valente wrote:
> Tejun, could you put your switch-off-io-cost code into a standalone
> patch, so that I can put it together with this one in a complete
> series?

It was more of a proof-of-concept / example, so the note in the email
that the code is free to be modified / used any way you see fit.  That
said, if you like it as it is, I can surely prep it as a standalone
patch.

Thanks.

-- 
tejun

^ permalink raw reply	[flat|nested] 25+ messages in thread

* Re: [PATCH 0/1] block, bfq: remove bfq prefix from cgroups filenames
  2019-09-16 15:16       ` Tejun Heo
@ 2019-09-16 15:21         ` Paolo Valente
  2019-09-16 16:01           ` Jens Axboe
  0 siblings, 1 reply; 25+ messages in thread
From: Paolo Valente @ 2019-09-16 15:21 UTC (permalink / raw)
  To: Tejun Heo
  Cc: Jens Axboe, linux-block, linux-kernel, Ulf Hansson,
	Linus Walleij, noreply-spamdigest via bfq-iosched,
	Oleksandr Natalenko, cgroups



> Il giorno 16 set 2019, alle ore 17:16, Tejun Heo <tj@kernel.org> ha scritto:
> 
> Hello, Paolo.
> 
> On Mon, Sep 16, 2019 at 05:07:29PM +0200, Paolo Valente wrote:
>> Tejun, could you put your switch-off-io-cost code into a standalone
>> patch, so that I can put it together with this one in a complete
>> series?
> 
> It was more of a proof-of-concept / example, so the note in the email
> that the code is free to be modified / used any way you see fit.  That
> said, if you like it as it is, I can surely prep it as a standalone
> patch.
> 

AFAICT your proposal contains no evident error.  Plus, no one seems to
have complained about the idea (regardless from the exact
implementation).  So I guess the best next step is to go for it.

Thanks,
Paolo

> Thanks.
> 
> -- 
> tejun


^ permalink raw reply	[flat|nested] 25+ messages in thread

* Re: [PATCH 0/1] block, bfq: remove bfq prefix from cgroups filenames
  2019-09-16 15:21         ` Paolo Valente
@ 2019-09-16 16:01           ` Jens Axboe
  2019-09-16 16:45             ` Paolo Valente
  0 siblings, 1 reply; 25+ messages in thread
From: Jens Axboe @ 2019-09-16 16:01 UTC (permalink / raw)
  To: Paolo Valente, Tejun Heo
  Cc: linux-block, linux-kernel, Ulf Hansson, Linus Walleij,
	noreply-spamdigest via bfq-iosched, Oleksandr Natalenko, cgroups

On 9/16/19 9:21 AM, Paolo Valente wrote:
> 
> 
>> Il giorno 16 set 2019, alle ore 17:16, Tejun Heo <tj@kernel.org> ha scritto:
>>
>> Hello, Paolo.
>>
>> On Mon, Sep 16, 2019 at 05:07:29PM +0200, Paolo Valente wrote:
>>> Tejun, could you put your switch-off-io-cost code into a standalone
>>> patch, so that I can put it together with this one in a complete
>>> series?
>>
>> It was more of a proof-of-concept / example, so the note in the email
>> that the code is free to be modified / used any way you see fit.  That
>> said, if you like it as it is, I can surely prep it as a standalone
>> patch.
>>
> 
> AFAICT your proposal contains no evident error.  Plus, no one seems to
> have complained about the idea (regardless from the exact
> implementation).  So I guess the best next step is to go for it.

Not filling me with a lot of confidence that you actually tested it?

-- 
Jens Axboe


^ permalink raw reply	[flat|nested] 25+ messages in thread

* Re: [PATCH 0/1] block, bfq: remove bfq prefix from cgroups filenames
  2019-09-16 16:01           ` Jens Axboe
@ 2019-09-16 16:45             ` Paolo Valente
  0 siblings, 0 replies; 25+ messages in thread
From: Paolo Valente @ 2019-09-16 16:45 UTC (permalink / raw)
  To: Jens Axboe
  Cc: Tejun Heo, linux-block, linux-kernel, Ulf Hansson, Linus Walleij,
	noreply-spamdigest via bfq-iosched, Oleksandr Natalenko, cgroups



> Il giorno 16 set 2019, alle ore 18:01, Jens Axboe <axboe@kernel.dk> ha scritto:
> 
> On 9/16/19 9:21 AM, Paolo Valente wrote:
>> 
>> 
>>> Il giorno 16 set 2019, alle ore 17:16, Tejun Heo <tj@kernel.org> ha scritto:
>>> 
>>> Hello, Paolo.
>>> 
>>> On Mon, Sep 16, 2019 at 05:07:29PM +0200, Paolo Valente wrote:
>>>> Tejun, could you put your switch-off-io-cost code into a standalone
>>>> patch, so that I can put it together with this one in a complete
>>>> series?
>>> 
>>> It was more of a proof-of-concept / example, so the note in the email
>>> that the code is free to be modified / used any way you see fit.  That
>>> said, if you like it as it is, I can surely prep it as a standalone
>>> patch.
>>> 
>> 
>> AFAICT your proposal contains no evident error.  Plus, no one seems to
>> have complained about the idea (regardless from the exact
>> implementation).  So I guess the best next step is to go for it.
> 
> Not filling me with a lot of confidence that you actually tested it?
> 

Tested it too. Waiting for Tejun's patch to re-submit it with mine.

Thanks,
Paolo

> -- 
> Jens Axboe


^ permalink raw reply	[flat|nested] 25+ messages in thread

* Re: [PATCH 1/1] block, bfq: delete "bfq" prefix from cgroup filenames
  2019-04-08 15:05         ` Jens Axboe
  2019-04-08 15:06           ` Paolo Valente
  2019-04-08 15:08           ` Johannes Thumshirn
@ 2019-04-10 11:42           ` Ulf Hansson
  2 siblings, 0 replies; 25+ messages in thread
From: Ulf Hansson @ 2019-04-10 11:42 UTC (permalink / raw)
  To: Jens Axboe
  Cc: Johannes Thumshirn, Paolo Valente, linux-block, linux-kernel,
	Linus Walleij, Mark Brown, Paolo Valente' via bfq-iosched,
	Oleksandr Natalenko, Angelo Ruocco, lennart, mkoutny

On Mon, 8 Apr 2019 at 17:05, Jens Axboe <axboe@kernel.dk> wrote:
>
> On 4/8/19 9:04 AM, Johannes Thumshirn wrote:
> > [+Cc Michal ]
> > On Mon, Apr 08, 2019 at 04:54:39PM +0200, Paolo Valente wrote:
> >>
> >>
> >>> Il giorno 8 apr 2019, alle ore 16:49, Johannes Thumshirn <jthumshirn@suse.de> ha scritto:
> >>>
> >>> On Mon, Apr 08, 2019 at 04:39:35PM +0200, Paolo Valente wrote:
> >>>> From: Angelo Ruocco <angeloruocco90@gmail.com>
> >>>>
> >>>> When bfq was merged into mainline, there were two I/O schedulers that
> >>>> implemented the proportional-share policy: bfq for blk-mq and cfq for
> >>>> legacy blk. bfq's interface files in the blkio/io controller have the
> >>>> same names as cfq. But the cgroups interface doesn't allow two
> >>>> entities to use the same name for their files, so for bfq we had to
> >>>> prepend the "bfq" prefix to each of its files. However no legacy code
> >>>> uses these modified file names. This naming also causes confusion, as,
> >>>> e.g., in [1].
> >>>>
> >>>> Now cfq has gone with legacy blk, so there is no need any longer for
> >>>> these prefixes in (the never used) bfq names. In view of this fact, this
> >>>> commit removes these prefixes, thereby enabling legacy code to truly
> >>>> use the proportional share policy in blk-mq.
> >>>>
> >>>> [1] https://github.com/systemd/systemd/issues/7057
> >>>
> >>> Hmm, but isn't this a user-space facing interface and thus some sort of ABI?
> >>> Do you know what's using it and what breaks due to this conversion?
> >>>
> >>
> >> Yep, but AFAIK, the problem is exactly the opposite: nobody uses these
> >> names for the proportional-share policy, or wants to use these names.  I'm
> >> CCing Lennart too, in case he has some improbable news on this.
> >>
> >> So the idea is to align names to what people expect, possibly before
> >> more confusion arises.
> >
> > OK, crazy idea, not sure if Jens and Tejun will beat me for this, but
> > symlinks?
> >
> > This way we can a) keep the old files and b) have them point to the new (a.k.a
> > cfq style) files.
>
> I did consider that, and that would be doable. But honestly, I'm having a
> hard time seeing what issue we are attempting to fix by doing this.

Jens, didn't we actually break userspace ABI when dropping the legacy
block code and its I/O schedulers?

So, to me, it seems like introducing symlinks as suggested above,
would actually fix this "regression", wouldn't it?

Kind regards
Uffe

^ permalink raw reply	[flat|nested] 25+ messages in thread

* Re: [PATCH 1/1] block, bfq: delete "bfq" prefix from cgroup filenames
  2019-04-08 15:17               ` Jens Axboe
@ 2019-04-08 17:01                 ` Paolo Valente
  0 siblings, 0 replies; 25+ messages in thread
From: Paolo Valente @ 2019-04-08 17:01 UTC (permalink / raw)
  To: Jens Axboe
  Cc: Johannes Thumshirn, linux-block, linux-kernel, Ulf Hansson,
	Linus Walleij, Mark Brown, Paolo Valente' via bfq-iosched,
	Oleksandr Natalenko, Angelo Ruocco, lennart, mkoutny



> Il giorno 8 apr 2019, alle ore 17:17, Jens Axboe <axboe@kernel.dk> ha scritto:
> 
> On 4/8/19 9:14 AM, Paolo Valente wrote:
>> 
>> 
>>> Il giorno 8 apr 2019, alle ore 17:08, Johannes Thumshirn <jthumshirn@suse.de> ha scritto:
>>> 
>>> On Mon, Apr 08, 2019 at 09:05:19AM -0600, Jens Axboe wrote:
>>>> I did consider that, and that would be doable. But honestly, I'm having a
>>>> hard time seeing what issue we are attempting to fix by doing this.
>>> 
>>> Yeah, I guess the real fix would be to update the documentation and the
>>> expectations user-space has. Including eventual re-write of some udev rules or
>>> whatever is facing these files. But to me that sounds more like a systemd or
>>> even distro thing than a kernel thing.
>>> 
>> 
>> Unfortunately the user-space people I have interacted with find crazy
>> to have to change their software to call bfq.weight the weight of a
>> group.  And are not willing to do it [1].
> 
> Then you need to educate them.

I'm not sure that educate is the right verb (I don't like the current
messy solution either).  But I'll do my best to inform people when
I'll have the opportunity to do it.

> Some of the issues were called out years
> ago, at the time when we could have potentially renamed.

Yeah, a good window was 5.0, and at that time we tried with a more
general solution.  But we failed.


> A rename now
> will solve nothing.
> 

I see your point, but I don't agree this rename would solve nothing.
The real bad thing is not having done this before.  Changing names
that nobody uses, to names that everybody already uses, but wrongly,
would instantaneously improve the situation a lot.  And it is what
userspace already asked explicitly for [1].  Without this simple
change, it will take a lot for all the inconsistent documentation
spread around the world to be synced.  And for all legacy software to
be changed, assuming it will all be changed.

Paolo

[1] https://github.com/systemd/systemd/issues/7057

> -- 
> Jens Axboe


^ permalink raw reply	[flat|nested] 25+ messages in thread

* Re: [PATCH 1/1] block, bfq: delete "bfq" prefix from cgroup filenames
  2019-04-08 15:13             ` Jens Axboe
@ 2019-04-08 15:19               ` Paolo Valente
  0 siblings, 0 replies; 25+ messages in thread
From: Paolo Valente @ 2019-04-08 15:19 UTC (permalink / raw)
  To: Jens Axboe
  Cc: Johannes Thumshirn, linux-block, linux-kernel, Ulf Hansson,
	Linus Walleij, Mark Brown, Paolo Valente' via bfq-iosched,
	Oleksandr Natalenko, Angelo Ruocco, lennart, mkoutny



> Il giorno 8 apr 2019, alle ore 17:13, Jens Axboe <axboe@kernel.dk> ha scritto:
> 
> On 4/8/19 9:08 AM, Johannes Thumshirn wrote:
>> On Mon, Apr 08, 2019 at 09:05:19AM -0600, Jens Axboe wrote:
>>> I did consider that, and that would be doable. But honestly, I'm having a
>>> hard time seeing what issue we are attempting to fix by doing this.
>> 
>> Yeah, I guess the real fix would be to update the documentation and the
>> expectations user-space has. Including eventual re-write of some udev rules or
>> whatever is facing these files. But to me that sounds more like a systemd or
>> even distro thing than a kernel thing.
> 
> I agree. Trying to force someones hand by renaming isn't going to fix
> anything, but it will potentially cause issues.
> 

Potential issues against concrete, big issues already with us.  The
proportional share interface doesn't match the idea people have of it.

I don't want to push for this solution, but we cannot pretend we don't
have a big problem already.  Any solution that could really work is ok
for me, including symlinks.

Thanks,
Paolo

> -- 
> Jens Axboe
> 


^ permalink raw reply	[flat|nested] 25+ messages in thread

* Re: [PATCH 1/1] block, bfq: delete "bfq" prefix from cgroup filenames
  2019-04-08 15:14             ` Paolo Valente
@ 2019-04-08 15:17               ` Jens Axboe
  2019-04-08 17:01                 ` Paolo Valente
  0 siblings, 1 reply; 25+ messages in thread
From: Jens Axboe @ 2019-04-08 15:17 UTC (permalink / raw)
  To: Paolo Valente, Johannes Thumshirn
  Cc: linux-block, linux-kernel, Ulf Hansson, Linus Walleij,
	Mark Brown, Paolo Valente' via bfq-iosched,
	Oleksandr Natalenko, Angelo Ruocco, lennart, mkoutny

On 4/8/19 9:14 AM, Paolo Valente wrote:
> 
> 
>> Il giorno 8 apr 2019, alle ore 17:08, Johannes Thumshirn <jthumshirn@suse.de> ha scritto:
>>
>> On Mon, Apr 08, 2019 at 09:05:19AM -0600, Jens Axboe wrote:
>>> I did consider that, and that would be doable. But honestly, I'm having a
>>> hard time seeing what issue we are attempting to fix by doing this.
>>
>> Yeah, I guess the real fix would be to update the documentation and the
>> expectations user-space has. Including eventual re-write of some udev rules or
>> whatever is facing these files. But to me that sounds more like a systemd or
>> even distro thing than a kernel thing.
>>
> 
> Unfortunately the user-space people I have interacted with find crazy
> to have to change their software to call bfq.weight the weight of a
> group.  And are not willing to do it [1].

Then you need to educate them. Some of the issues were called out years
ago, at the time when we could have potentially renamed. A rename now
will solve nothing.

-- 
Jens Axboe


^ permalink raw reply	[flat|nested] 25+ messages in thread

* Re: [PATCH 1/1] block, bfq: delete "bfq" prefix from cgroup filenames
  2019-04-08 15:11             ` Jens Axboe
@ 2019-04-08 15:15               ` Paolo Valente
  0 siblings, 0 replies; 25+ messages in thread
From: Paolo Valente @ 2019-04-08 15:15 UTC (permalink / raw)
  To: Jens Axboe
  Cc: Johannes Thumshirn, linux-block, linux-kernel, Ulf Hansson,
	Linus Walleij, Mark Brown, Paolo Valente' via bfq-iosched,
	Oleksandr Natalenko, Angelo Ruocco, lennart, mkoutny



> Il giorno 8 apr 2019, alle ore 17:11, Jens Axboe <axboe@kernel.dk> ha scritto:
> 
> On 4/8/19 9:06 AM, Paolo Valente wrote:
>> 
>> 
>>> Il giorno 8 apr 2019, alle ore 17:05, Jens Axboe <axboe@kernel.dk> ha scritto:
>>> 
>>> On 4/8/19 9:04 AM, Johannes Thumshirn wrote:
>>>> [+Cc Michal ]
>>>> On Mon, Apr 08, 2019 at 04:54:39PM +0200, Paolo Valente wrote:
>>>>> 
>>>>> 
>>>>>> Il giorno 8 apr 2019, alle ore 16:49, Johannes Thumshirn <jthumshirn@suse.de> ha scritto:
>>>>>> 
>>>>>> On Mon, Apr 08, 2019 at 04:39:35PM +0200, Paolo Valente wrote:
>>>>>>> From: Angelo Ruocco <angeloruocco90@gmail.com>
>>>>>>> 
>>>>>>> When bfq was merged into mainline, there were two I/O schedulers that
>>>>>>> implemented the proportional-share policy: bfq for blk-mq and cfq for
>>>>>>> legacy blk. bfq's interface files in the blkio/io controller have the
>>>>>>> same names as cfq. But the cgroups interface doesn't allow two
>>>>>>> entities to use the same name for their files, so for bfq we had to
>>>>>>> prepend the "bfq" prefix to each of its files. However no legacy code
>>>>>>> uses these modified file names. This naming also causes confusion, as,
>>>>>>> e.g., in [1].
>>>>>>> 
>>>>>>> Now cfq has gone with legacy blk, so there is no need any longer for
>>>>>>> these prefixes in (the never used) bfq names. In view of this fact, this
>>>>>>> commit removes these prefixes, thereby enabling legacy code to truly
>>>>>>> use the proportional share policy in blk-mq.
>>>>>>> 
>>>>>>> [1] https://github.com/systemd/systemd/issues/7057
>>>>>> 
>>>>>> Hmm, but isn't this a user-space facing interface and thus some sort of ABI?
>>>>>> Do you know what's using it and what breaks due to this conversion?
>>>>>> 
>>>>> 
>>>>> Yep, but AFAIK, the problem is exactly the opposite: nobody uses these
>>>>> names for the proportional-share policy, or wants to use these names. I'm
>>>>> CCing Lennart too, in case he has some improbable news on this.
>>>>> 
>>>>> So the idea is to align names to what people expect, possibly before
>>>>> more confusion arises.
>>>> 
>>>> OK, crazy idea, not sure if Jens and Tejun will beat me for this, but
>>>> symlinks?
>>>> 
>>>> This way we can a) keep the old files and b) have them point to the new (a.k.a
>>>> cfq style) files.
>>> 
>>> I did consider that, and that would be doable. But honestly, I'm having a
>>> hard time seeing what issue we are attempting to fix by doing this.
>>> 
>> 
>> The problem is ~100% of people and software believing to set weights and not doing it.
> 
> I'm sorry, but I don't know what that means?
> 

It means that people and code set weights, not bfq.weights.

Thanks,
Paolo

> -- 
> Jens Axboe


^ permalink raw reply	[flat|nested] 25+ messages in thread

* Re: [PATCH 1/1] block, bfq: delete "bfq" prefix from cgroup filenames
  2019-04-08 15:08           ` Johannes Thumshirn
  2019-04-08 15:13             ` Jens Axboe
@ 2019-04-08 15:14             ` Paolo Valente
  2019-04-08 15:17               ` Jens Axboe
  1 sibling, 1 reply; 25+ messages in thread
From: Paolo Valente @ 2019-04-08 15:14 UTC (permalink / raw)
  To: Johannes Thumshirn
  Cc: Jens Axboe, linux-block, linux-kernel, Ulf Hansson,
	Linus Walleij, Mark Brown, Paolo Valente' via bfq-iosched,
	Oleksandr Natalenko, Angelo Ruocco, lennart, mkoutny



> Il giorno 8 apr 2019, alle ore 17:08, Johannes Thumshirn <jthumshirn@suse.de> ha scritto:
> 
> On Mon, Apr 08, 2019 at 09:05:19AM -0600, Jens Axboe wrote:
>> I did consider that, and that would be doable. But honestly, I'm having a
>> hard time seeing what issue we are attempting to fix by doing this.
> 
> Yeah, I guess the real fix would be to update the documentation and the
> expectations user-space has. Including eventual re-write of some udev rules or
> whatever is facing these files. But to me that sounds more like a systemd or
> even distro thing than a kernel thing.
> 

Unfortunately the user-space people I have interacted with find crazy
to have to change their software to call bfq.weight the weight of a
group.  And are not willing to do it [1].

Thanks,
Paolo

[1] https://github.com/systemd/systemd/issues/7057

> Byte,
> 	Johannes
> -- 
> Johannes Thumshirn                            SUSE Labs Filesystems
> jthumshirn@suse.de                                +49 911 74053 689
> SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
> GF: Felix Imendörffer, Mary Higgins, Sri Rasiah
> HRB 21284 (AG Nürnberg)
> Key fingerprint = EC38 9CAB C2C4 F25D 8600 D0D0 0393 969D 2D76 0850


^ permalink raw reply	[flat|nested] 25+ messages in thread

* Re: [PATCH 1/1] block, bfq: delete "bfq" prefix from cgroup filenames
  2019-04-08 15:08           ` Johannes Thumshirn
@ 2019-04-08 15:13             ` Jens Axboe
  2019-04-08 15:19               ` Paolo Valente
  2019-04-08 15:14             ` Paolo Valente
  1 sibling, 1 reply; 25+ messages in thread
From: Jens Axboe @ 2019-04-08 15:13 UTC (permalink / raw)
  To: Johannes Thumshirn
  Cc: Paolo Valente, linux-block, linux-kernel, Ulf Hansson,
	Linus Walleij, Mark Brown, Paolo Valente' via bfq-iosched,
	Oleksandr Natalenko, Angelo Ruocco, lennart, mkoutny

On 4/8/19 9:08 AM, Johannes Thumshirn wrote:
> On Mon, Apr 08, 2019 at 09:05:19AM -0600, Jens Axboe wrote:
>> I did consider that, and that would be doable. But honestly, I'm having a
>> hard time seeing what issue we are attempting to fix by doing this.
> 
> Yeah, I guess the real fix would be to update the documentation and the
> expectations user-space has. Including eventual re-write of some udev rules or
> whatever is facing these files. But to me that sounds more like a systemd or
> even distro thing than a kernel thing.

I agree. Trying to force someones hand by renaming isn't going to fix
anything, but it will potentially cause issues.

-- 
Jens Axboe


^ permalink raw reply	[flat|nested] 25+ messages in thread

* Re: [PATCH 1/1] block, bfq: delete "bfq" prefix from cgroup filenames
  2019-04-08 15:06           ` Paolo Valente
@ 2019-04-08 15:11             ` Jens Axboe
  2019-04-08 15:15               ` Paolo Valente
  0 siblings, 1 reply; 25+ messages in thread
From: Jens Axboe @ 2019-04-08 15:11 UTC (permalink / raw)
  To: Paolo Valente
  Cc: Johannes Thumshirn, linux-block, linux-kernel, Ulf Hansson,
	Linus Walleij, Mark Brown, Paolo Valente' via bfq-iosched,
	Oleksandr Natalenko, Angelo Ruocco, lennart, mkoutny

On 4/8/19 9:06 AM, Paolo Valente wrote:
> 
> 
>> Il giorno 8 apr 2019, alle ore 17:05, Jens Axboe <axboe@kernel.dk> ha scritto:
>>
>> On 4/8/19 9:04 AM, Johannes Thumshirn wrote:
>>> [+Cc Michal ]
>>> On Mon, Apr 08, 2019 at 04:54:39PM +0200, Paolo Valente wrote:
>>>>
>>>>
>>>>> Il giorno 8 apr 2019, alle ore 16:49, Johannes Thumshirn <jthumshirn@suse.de> ha scritto:
>>>>>
>>>>> On Mon, Apr 08, 2019 at 04:39:35PM +0200, Paolo Valente wrote:
>>>>>> From: Angelo Ruocco <angeloruocco90@gmail.com>
>>>>>>
>>>>>> When bfq was merged into mainline, there were two I/O schedulers that
>>>>>> implemented the proportional-share policy: bfq for blk-mq and cfq for
>>>>>> legacy blk. bfq's interface files in the blkio/io controller have the
>>>>>> same names as cfq. But the cgroups interface doesn't allow two
>>>>>> entities to use the same name for their files, so for bfq we had to
>>>>>> prepend the "bfq" prefix to each of its files. However no legacy code
>>>>>> uses these modified file names. This naming also causes confusion, as,
>>>>>> e.g., in [1].
>>>>>>
>>>>>> Now cfq has gone with legacy blk, so there is no need any longer for
>>>>>> these prefixes in (the never used) bfq names. In view of this fact, this
>>>>>> commit removes these prefixes, thereby enabling legacy code to truly
>>>>>> use the proportional share policy in blk-mq.
>>>>>>
>>>>>> [1] https://github.com/systemd/systemd/issues/7057
>>>>>
>>>>> Hmm, but isn't this a user-space facing interface and thus some sort of ABI?
>>>>> Do you know what's using it and what breaks due to this conversion?
>>>>>
>>>>
>>>> Yep, but AFAIK, the problem is exactly the opposite: nobody uses these
>>>> names for the proportional-share policy, or wants to use these names.  I'm
>>>> CCing Lennart too, in case he has some improbable news on this.
>>>>
>>>> So the idea is to align names to what people expect, possibly before
>>>> more confusion arises.
>>>
>>> OK, crazy idea, not sure if Jens and Tejun will beat me for this, but
>>> symlinks?
>>>
>>> This way we can a) keep the old files and b) have them point to the new (a.k.a
>>> cfq style) files.
>>
>> I did consider that, and that would be doable. But honestly, I'm having a
>> hard time seeing what issue we are attempting to fix by doing this.
>>
> 
> The problem is ~100% of people and software believing to set weights and not doing it.

I'm sorry, but I don't know what that means?

-- 
Jens Axboe


^ permalink raw reply	[flat|nested] 25+ messages in thread

* Re: [PATCH 1/1] block, bfq: delete "bfq" prefix from cgroup filenames
  2019-04-08 15:05         ` Jens Axboe
  2019-04-08 15:06           ` Paolo Valente
@ 2019-04-08 15:08           ` Johannes Thumshirn
  2019-04-08 15:13             ` Jens Axboe
  2019-04-08 15:14             ` Paolo Valente
  2019-04-10 11:42           ` Ulf Hansson
  2 siblings, 2 replies; 25+ messages in thread
From: Johannes Thumshirn @ 2019-04-08 15:08 UTC (permalink / raw)
  To: Jens Axboe
  Cc: Paolo Valente, linux-block, linux-kernel, Ulf Hansson,
	Linus Walleij, Mark Brown, Paolo Valente' via bfq-iosched,
	Oleksandr Natalenko, Angelo Ruocco, lennart, mkoutny

On Mon, Apr 08, 2019 at 09:05:19AM -0600, Jens Axboe wrote:
> I did consider that, and that would be doable. But honestly, I'm having a
> hard time seeing what issue we are attempting to fix by doing this.

Yeah, I guess the real fix would be to update the documentation and the
expectations user-space has. Including eventual re-write of some udev rules or
whatever is facing these files. But to me that sounds more like a systemd or
even distro thing than a kernel thing.

Byte,
	Johannes
-- 
Johannes Thumshirn                            SUSE Labs Filesystems
jthumshirn@suse.de                                +49 911 74053 689
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: Felix Imendörffer, Mary Higgins, Sri Rasiah
HRB 21284 (AG Nürnberg)
Key fingerprint = EC38 9CAB C2C4 F25D 8600 D0D0 0393 969D 2D76 0850

^ permalink raw reply	[flat|nested] 25+ messages in thread

* Re: [PATCH 1/1] block, bfq: delete "bfq" prefix from cgroup filenames
  2019-04-08 15:05         ` Jens Axboe
@ 2019-04-08 15:06           ` Paolo Valente
  2019-04-08 15:11             ` Jens Axboe
  2019-04-08 15:08           ` Johannes Thumshirn
  2019-04-10 11:42           ` Ulf Hansson
  2 siblings, 1 reply; 25+ messages in thread
From: Paolo Valente @ 2019-04-08 15:06 UTC (permalink / raw)
  To: Jens Axboe
  Cc: Johannes Thumshirn, linux-block, linux-kernel, Ulf Hansson,
	Linus Walleij, Mark Brown, Paolo Valente' via bfq-iosched,
	Oleksandr Natalenko, Angelo Ruocco, lennart, mkoutny



> Il giorno 8 apr 2019, alle ore 17:05, Jens Axboe <axboe@kernel.dk> ha scritto:
> 
> On 4/8/19 9:04 AM, Johannes Thumshirn wrote:
>> [+Cc Michal ]
>> On Mon, Apr 08, 2019 at 04:54:39PM +0200, Paolo Valente wrote:
>>> 
>>> 
>>>> Il giorno 8 apr 2019, alle ore 16:49, Johannes Thumshirn <jthumshirn@suse.de> ha scritto:
>>>> 
>>>> On Mon, Apr 08, 2019 at 04:39:35PM +0200, Paolo Valente wrote:
>>>>> From: Angelo Ruocco <angeloruocco90@gmail.com>
>>>>> 
>>>>> When bfq was merged into mainline, there were two I/O schedulers that
>>>>> implemented the proportional-share policy: bfq for blk-mq and cfq for
>>>>> legacy blk. bfq's interface files in the blkio/io controller have the
>>>>> same names as cfq. But the cgroups interface doesn't allow two
>>>>> entities to use the same name for their files, so for bfq we had to
>>>>> prepend the "bfq" prefix to each of its files. However no legacy code
>>>>> uses these modified file names. This naming also causes confusion, as,
>>>>> e.g., in [1].
>>>>> 
>>>>> Now cfq has gone with legacy blk, so there is no need any longer for
>>>>> these prefixes in (the never used) bfq names. In view of this fact, this
>>>>> commit removes these prefixes, thereby enabling legacy code to truly
>>>>> use the proportional share policy in blk-mq.
>>>>> 
>>>>> [1] https://github.com/systemd/systemd/issues/7057
>>>> 
>>>> Hmm, but isn't this a user-space facing interface and thus some sort of ABI?
>>>> Do you know what's using it and what breaks due to this conversion?
>>>> 
>>> 
>>> Yep, but AFAIK, the problem is exactly the opposite: nobody uses these
>>> names for the proportional-share policy, or wants to use these names.  I'm
>>> CCing Lennart too, in case he has some improbable news on this.
>>> 
>>> So the idea is to align names to what people expect, possibly before
>>> more confusion arises.
>> 
>> OK, crazy idea, not sure if Jens and Tejun will beat me for this, but
>> symlinks?
>> 
>> This way we can a) keep the old files and b) have them point to the new (a.k.a
>> cfq style) files.
> 
> I did consider that, and that would be doable. But honestly, I'm having a
> hard time seeing what issue we are attempting to fix by doing this.
> 

The problem is ~100% of people and software believing to set weights and not doing it.

Paolo

> -- 
> Jens Axboe


^ permalink raw reply	[flat|nested] 25+ messages in thread

* Re: [PATCH 1/1] block, bfq: delete "bfq" prefix from cgroup filenames
  2019-04-08 15:04       ` Johannes Thumshirn
@ 2019-04-08 15:05         ` Jens Axboe
  2019-04-08 15:06           ` Paolo Valente
                             ` (2 more replies)
  0 siblings, 3 replies; 25+ messages in thread
From: Jens Axboe @ 2019-04-08 15:05 UTC (permalink / raw)
  To: Johannes Thumshirn, Paolo Valente
  Cc: linux-block, linux-kernel, Ulf Hansson, Linus Walleij,
	Mark Brown, Paolo Valente' via bfq-iosched,
	Oleksandr Natalenko, Angelo Ruocco, lennart, mkoutny

On 4/8/19 9:04 AM, Johannes Thumshirn wrote:
> [+Cc Michal ]
> On Mon, Apr 08, 2019 at 04:54:39PM +0200, Paolo Valente wrote:
>>
>>
>>> Il giorno 8 apr 2019, alle ore 16:49, Johannes Thumshirn <jthumshirn@suse.de> ha scritto:
>>>
>>> On Mon, Apr 08, 2019 at 04:39:35PM +0200, Paolo Valente wrote:
>>>> From: Angelo Ruocco <angeloruocco90@gmail.com>
>>>>
>>>> When bfq was merged into mainline, there were two I/O schedulers that
>>>> implemented the proportional-share policy: bfq for blk-mq and cfq for
>>>> legacy blk. bfq's interface files in the blkio/io controller have the
>>>> same names as cfq. But the cgroups interface doesn't allow two
>>>> entities to use the same name for their files, so for bfq we had to
>>>> prepend the "bfq" prefix to each of its files. However no legacy code
>>>> uses these modified file names. This naming also causes confusion, as,
>>>> e.g., in [1].
>>>>
>>>> Now cfq has gone with legacy blk, so there is no need any longer for
>>>> these prefixes in (the never used) bfq names. In view of this fact, this
>>>> commit removes these prefixes, thereby enabling legacy code to truly
>>>> use the proportional share policy in blk-mq.
>>>>
>>>> [1] https://github.com/systemd/systemd/issues/7057
>>>
>>> Hmm, but isn't this a user-space facing interface and thus some sort of ABI?
>>> Do you know what's using it and what breaks due to this conversion?
>>>
>>
>> Yep, but AFAIK, the problem is exactly the opposite: nobody uses these
>> names for the proportional-share policy, or wants to use these names.  I'm
>> CCing Lennart too, in case he has some improbable news on this.
>>
>> So the idea is to align names to what people expect, possibly before
>> more confusion arises.
> 
> OK, crazy idea, not sure if Jens and Tejun will beat me for this, but
> symlinks?
> 
> This way we can a) keep the old files and b) have them point to the new (a.k.a
> cfq style) files.

I did consider that, and that would be doable. But honestly, I'm having a
hard time seeing what issue we are attempting to fix by doing this.

-- 
Jens Axboe


^ permalink raw reply	[flat|nested] 25+ messages in thread

* Re: [PATCH 1/1] block, bfq: delete "bfq" prefix from cgroup filenames
  2019-04-08 14:54     ` Paolo Valente
  2019-04-08 15:01       ` Jens Axboe
@ 2019-04-08 15:04       ` Johannes Thumshirn
  2019-04-08 15:05         ` Jens Axboe
  1 sibling, 1 reply; 25+ messages in thread
From: Johannes Thumshirn @ 2019-04-08 15:04 UTC (permalink / raw)
  To: Paolo Valente
  Cc: Jens Axboe, linux-block, linux-kernel, Ulf Hansson,
	Linus Walleij, Mark Brown, Paolo Valente' via bfq-iosched,
	Oleksandr Natalenko, Angelo Ruocco, lennart, mkoutny

[+Cc Michal ]
On Mon, Apr 08, 2019 at 04:54:39PM +0200, Paolo Valente wrote:
> 
> 
> > Il giorno 8 apr 2019, alle ore 16:49, Johannes Thumshirn <jthumshirn@suse.de> ha scritto:
> > 
> > On Mon, Apr 08, 2019 at 04:39:35PM +0200, Paolo Valente wrote:
> >> From: Angelo Ruocco <angeloruocco90@gmail.com>
> >> 
> >> When bfq was merged into mainline, there were two I/O schedulers that
> >> implemented the proportional-share policy: bfq for blk-mq and cfq for
> >> legacy blk. bfq's interface files in the blkio/io controller have the
> >> same names as cfq. But the cgroups interface doesn't allow two
> >> entities to use the same name for their files, so for bfq we had to
> >> prepend the "bfq" prefix to each of its files. However no legacy code
> >> uses these modified file names. This naming also causes confusion, as,
> >> e.g., in [1].
> >> 
> >> Now cfq has gone with legacy blk, so there is no need any longer for
> >> these prefixes in (the never used) bfq names. In view of this fact, this
> >> commit removes these prefixes, thereby enabling legacy code to truly
> >> use the proportional share policy in blk-mq.
> >> 
> >> [1] https://github.com/systemd/systemd/issues/7057
> > 
> > Hmm, but isn't this a user-space facing interface and thus some sort of ABI?
> > Do you know what's using it and what breaks due to this conversion?
> > 
> 
> Yep, but AFAIK, the problem is exactly the opposite: nobody uses these
> names for the proportional-share policy, or wants to use these names.  I'm
> CCing Lennart too, in case he has some improbable news on this.
> 
> So the idea is to align names to what people expect, possibly before
> more confusion arises.

OK, crazy idea, not sure if Jens and Tejun will beat me for this, but
symlinks?

This way we can a) keep the old files and b) have them point to the new (a.k.a
cfq style) files.

Byte,
	Johannes
-- 
Johannes Thumshirn                            SUSE Labs Filesystems
jthumshirn@suse.de                                +49 911 74053 689
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: Felix Imendörffer, Mary Higgins, Sri Rasiah
HRB 21284 (AG Nürnberg)
Key fingerprint = EC38 9CAB C2C4 F25D 8600 D0D0 0393 969D 2D76 0850

^ permalink raw reply	[flat|nested] 25+ messages in thread

* Re: [PATCH 1/1] block, bfq: delete "bfq" prefix from cgroup filenames
  2019-04-08 14:54     ` Paolo Valente
@ 2019-04-08 15:01       ` Jens Axboe
  2019-04-08 15:04       ` Johannes Thumshirn
  1 sibling, 0 replies; 25+ messages in thread
From: Jens Axboe @ 2019-04-08 15:01 UTC (permalink / raw)
  To: Paolo Valente, Johannes Thumshirn
  Cc: linux-block, linux-kernel, Ulf Hansson, Linus Walleij,
	Mark Brown, Paolo Valente' via bfq-iosched,
	Oleksandr Natalenko, Angelo Ruocco, lennart

On 4/8/19 8:54 AM, Paolo Valente wrote:
> 
> 
>> Il giorno 8 apr 2019, alle ore 16:49, Johannes Thumshirn <jthumshirn@suse.de> ha scritto:
>>
>> On Mon, Apr 08, 2019 at 04:39:35PM +0200, Paolo Valente wrote:
>>> From: Angelo Ruocco <angeloruocco90@gmail.com>
>>>
>>> When bfq was merged into mainline, there were two I/O schedulers that
>>> implemented the proportional-share policy: bfq for blk-mq and cfq for
>>> legacy blk. bfq's interface files in the blkio/io controller have the
>>> same names as cfq. But the cgroups interface doesn't allow two
>>> entities to use the same name for their files, so for bfq we had to
>>> prepend the "bfq" prefix to each of its files. However no legacy code
>>> uses these modified file names. This naming also causes confusion, as,
>>> e.g., in [1].
>>>
>>> Now cfq has gone with legacy blk, so there is no need any longer for
>>> these prefixes in (the never used) bfq names. In view of this fact, this
>>> commit removes these prefixes, thereby enabling legacy code to truly
>>> use the proportional share policy in blk-mq.
>>>
>>> [1] https://github.com/systemd/systemd/issues/7057
>>
>> Hmm, but isn't this a user-space facing interface and thus some sort of ABI?
>> Do you know what's using it and what breaks due to this conversion?
>>
> 
> Yep, but AFAIK, the problem is exactly the opposite: nobody uses these
> names for the proportional-share policy, or wants to use these names.  I'm
> CCing Lennart too, in case he has some improbable news on this.
> 
> So the idea is to align names to what people expect, possibly before
> more confusion arises.

We can't just rename them since they've already been in a shipped kernel.
The window for doing this passed long ago.

-- 
Jens Axboe


^ permalink raw reply	[flat|nested] 25+ messages in thread

* Re: [PATCH 1/1] block, bfq: delete "bfq" prefix from cgroup filenames
  2019-04-08 14:49   ` Johannes Thumshirn
@ 2019-04-08 14:54     ` Paolo Valente
  2019-04-08 15:01       ` Jens Axboe
  2019-04-08 15:04       ` Johannes Thumshirn
  0 siblings, 2 replies; 25+ messages in thread
From: Paolo Valente @ 2019-04-08 14:54 UTC (permalink / raw)
  To: Johannes Thumshirn
  Cc: Jens Axboe, linux-block, linux-kernel, Ulf Hansson,
	Linus Walleij, Mark Brown, Paolo Valente' via bfq-iosched,
	Oleksandr Natalenko, Angelo Ruocco, lennart



> Il giorno 8 apr 2019, alle ore 16:49, Johannes Thumshirn <jthumshirn@suse.de> ha scritto:
> 
> On Mon, Apr 08, 2019 at 04:39:35PM +0200, Paolo Valente wrote:
>> From: Angelo Ruocco <angeloruocco90@gmail.com>
>> 
>> When bfq was merged into mainline, there were two I/O schedulers that
>> implemented the proportional-share policy: bfq for blk-mq and cfq for
>> legacy blk. bfq's interface files in the blkio/io controller have the
>> same names as cfq. But the cgroups interface doesn't allow two
>> entities to use the same name for their files, so for bfq we had to
>> prepend the "bfq" prefix to each of its files. However no legacy code
>> uses these modified file names. This naming also causes confusion, as,
>> e.g., in [1].
>> 
>> Now cfq has gone with legacy blk, so there is no need any longer for
>> these prefixes in (the never used) bfq names. In view of this fact, this
>> commit removes these prefixes, thereby enabling legacy code to truly
>> use the proportional share policy in blk-mq.
>> 
>> [1] https://github.com/systemd/systemd/issues/7057
> 
> Hmm, but isn't this a user-space facing interface and thus some sort of ABI?
> Do you know what's using it and what breaks due to this conversion?
> 

Yep, but AFAIK, the problem is exactly the opposite: nobody uses these
names for the proportional-share policy, or wants to use these names.  I'm
CCing Lennart too, in case he has some improbable news on this.

So the idea is to align names to what people expect, possibly before
more confusion arises.

Thanks,
Paolo

> -- 
> Johannes Thumshirn                            SUSE Labs Filesystems
> jthumshirn@suse.de                                +49 911 74053 689
> SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
> GF: Felix Imendörffer, Mary Higgins, Sri Rasiah
> HRB 21284 (AG Nürnberg)
> Key fingerprint = EC38 9CAB C2C4 F25D 8600 D0D0 0393 969D 2D76 0850


^ permalink raw reply	[flat|nested] 25+ messages in thread

* Re: [PATCH 1/1] block, bfq: delete "bfq" prefix from cgroup filenames
  2019-04-08 14:39 ` [PATCH 1/1] block, bfq: delete "bfq" prefix " Paolo Valente
@ 2019-04-08 14:49   ` Johannes Thumshirn
  2019-04-08 14:54     ` Paolo Valente
  0 siblings, 1 reply; 25+ messages in thread
From: Johannes Thumshirn @ 2019-04-08 14:49 UTC (permalink / raw)
  To: Paolo Valente
  Cc: Jens Axboe, linux-block, linux-kernel, ulf.hansson,
	linus.walleij, broonie, bfq-iosched, oleksandr, Angelo Ruocco

On Mon, Apr 08, 2019 at 04:39:35PM +0200, Paolo Valente wrote:
> From: Angelo Ruocco <angeloruocco90@gmail.com>
> 
> When bfq was merged into mainline, there were two I/O schedulers that
> implemented the proportional-share policy: bfq for blk-mq and cfq for
> legacy blk. bfq's interface files in the blkio/io controller have the
> same names as cfq. But the cgroups interface doesn't allow two
> entities to use the same name for their files, so for bfq we had to
> prepend the "bfq" prefix to each of its files. However no legacy code
> uses these modified file names. This naming also causes confusion, as,
> e.g., in [1].
> 
> Now cfq has gone with legacy blk, so there is no need any longer for
> these prefixes in (the never used) bfq names. In view of this fact, this
> commit removes these prefixes, thereby enabling legacy code to truly
> use the proportional share policy in blk-mq.
> 
> [1] https://github.com/systemd/systemd/issues/7057

Hmm, but isn't this a user-space facing interface and thus some sort of ABI?
Do you know what's using it and what breaks due to this conversion?

-- 
Johannes Thumshirn                            SUSE Labs Filesystems
jthumshirn@suse.de                                +49 911 74053 689
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: Felix Imendörffer, Mary Higgins, Sri Rasiah
HRB 21284 (AG Nürnberg)
Key fingerprint = EC38 9CAB C2C4 F25D 8600 D0D0 0393 969D 2D76 0850

^ permalink raw reply	[flat|nested] 25+ messages in thread

* [PATCH 1/1] block, bfq: delete "bfq" prefix from cgroup filenames
  2019-04-08 14:39 [PATCH 0/1] bfq: remove prefixes from cgroup filenames Paolo Valente
@ 2019-04-08 14:39 ` " Paolo Valente
  2019-04-08 14:49   ` Johannes Thumshirn
  0 siblings, 1 reply; 25+ messages in thread
From: Paolo Valente @ 2019-04-08 14:39 UTC (permalink / raw)
  To: Jens Axboe
  Cc: linux-block, linux-kernel, ulf.hansson, linus.walleij, broonie,
	bfq-iosched, oleksandr, Angelo Ruocco, Paolo Valente

From: Angelo Ruocco <angeloruocco90@gmail.com>

When bfq was merged into mainline, there were two I/O schedulers that
implemented the proportional-share policy: bfq for blk-mq and cfq for
legacy blk. bfq's interface files in the blkio/io controller have the
same names as cfq. But the cgroups interface doesn't allow two
entities to use the same name for their files, so for bfq we had to
prepend the "bfq" prefix to each of its files. However no legacy code
uses these modified file names. This naming also causes confusion, as,
e.g., in [1].

Now cfq has gone with legacy blk, so there is no need any longer for
these prefixes in (the never used) bfq names. In view of this fact, this
commit removes these prefixes, thereby enabling legacy code to truly
use the proportional share policy in blk-mq.

[1] https://github.com/systemd/systemd/issues/7057

Signed-off-by: Angelo Ruocco <angeloruocco90@gmail.com>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
---
 block/bfq-cgroup.c | 46 +++++++++++++++++++++++-----------------------
 1 file changed, 23 insertions(+), 23 deletions(-)

diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c
index c6113af31960..319c2444dc71 100644
--- a/block/bfq-cgroup.c
+++ b/block/bfq-cgroup.c
@@ -1053,7 +1053,7 @@ struct blkcg_policy blkcg_policy_bfq = {
 
 struct cftype bfq_blkcg_legacy_files[] = {
 	{
-		.name = "bfq.weight",
+		.name = "weight",
 		.flags = CFTYPE_NOT_ON_ROOT,
 		.seq_show = bfq_io_show_weight,
 		.write_u64 = bfq_io_set_weight_legacy,
@@ -1061,42 +1061,42 @@ struct cftype bfq_blkcg_legacy_files[] = {
 
 	/* statistics, covers only the tasks in the bfqg */
 	{
-		.name = "bfq.io_service_bytes",
+		.name = "io_service_bytes",
 		.private = (unsigned long)&blkcg_policy_bfq,
 		.seq_show = blkg_print_stat_bytes,
 	},
 	{
-		.name = "bfq.io_serviced",
+		.name = "io_serviced",
 		.private = (unsigned long)&blkcg_policy_bfq,
 		.seq_show = blkg_print_stat_ios,
 	},
 #ifdef CONFIG_DEBUG_BLK_CGROUP
 	{
-		.name = "bfq.time",
+		.name = "time",
 		.private = offsetof(struct bfq_group, stats.time),
 		.seq_show = bfqg_print_stat,
 	},
 	{
-		.name = "bfq.sectors",
+		.name = "sectors",
 		.seq_show = bfqg_print_stat_sectors,
 	},
 	{
-		.name = "bfq.io_service_time",
+		.name = "io_service_time",
 		.private = offsetof(struct bfq_group, stats.service_time),
 		.seq_show = bfqg_print_rwstat,
 	},
 	{
-		.name = "bfq.io_wait_time",
+		.name = "io_wait_time",
 		.private = offsetof(struct bfq_group, stats.wait_time),
 		.seq_show = bfqg_print_rwstat,
 	},
 	{
-		.name = "bfq.io_merged",
+		.name = "io_merged",
 		.private = offsetof(struct bfq_group, stats.merged),
 		.seq_show = bfqg_print_rwstat,
 	},
 	{
-		.name = "bfq.io_queued",
+		.name = "io_queued",
 		.private = offsetof(struct bfq_group, stats.queued),
 		.seq_show = bfqg_print_rwstat,
 	},
@@ -1104,66 +1104,66 @@ struct cftype bfq_blkcg_legacy_files[] = {
 
 	/* the same statictics which cover the bfqg and its descendants */
 	{
-		.name = "bfq.io_service_bytes_recursive",
+		.name = "io_service_bytes_recursive",
 		.private = (unsigned long)&blkcg_policy_bfq,
 		.seq_show = blkg_print_stat_bytes_recursive,
 	},
 	{
-		.name = "bfq.io_serviced_recursive",
+		.name = "io_serviced_recursive",
 		.private = (unsigned long)&blkcg_policy_bfq,
 		.seq_show = blkg_print_stat_ios_recursive,
 	},
 #ifdef CONFIG_DEBUG_BLK_CGROUP
 	{
-		.name = "bfq.time_recursive",
+		.name = "time_recursive",
 		.private = offsetof(struct bfq_group, stats.time),
 		.seq_show = bfqg_print_stat_recursive,
 	},
 	{
-		.name = "bfq.sectors_recursive",
+		.name = "sectors_recursive",
 		.seq_show = bfqg_print_stat_sectors_recursive,
 	},
 	{
-		.name = "bfq.io_service_time_recursive",
+		.name = "io_service_time_recursive",
 		.private = offsetof(struct bfq_group, stats.service_time),
 		.seq_show = bfqg_print_rwstat_recursive,
 	},
 	{
-		.name = "bfq.io_wait_time_recursive",
+		.name = "io_wait_time_recursive",
 		.private = offsetof(struct bfq_group, stats.wait_time),
 		.seq_show = bfqg_print_rwstat_recursive,
 	},
 	{
-		.name = "bfq.io_merged_recursive",
+		.name = "io_merged_recursive",
 		.private = offsetof(struct bfq_group, stats.merged),
 		.seq_show = bfqg_print_rwstat_recursive,
 	},
 	{
-		.name = "bfq.io_queued_recursive",
+		.name = "io_queued_recursive",
 		.private = offsetof(struct bfq_group, stats.queued),
 		.seq_show = bfqg_print_rwstat_recursive,
 	},
 	{
-		.name = "bfq.avg_queue_size",
+		.name = "avg_queue_size",
 		.seq_show = bfqg_print_avg_queue_size,
 	},
 	{
-		.name = "bfq.group_wait_time",
+		.name = "group_wait_time",
 		.private = offsetof(struct bfq_group, stats.group_wait_time),
 		.seq_show = bfqg_print_stat,
 	},
 	{
-		.name = "bfq.idle_time",
+		.name = "idle_time",
 		.private = offsetof(struct bfq_group, stats.idle_time),
 		.seq_show = bfqg_print_stat,
 	},
 	{
-		.name = "bfq.empty_time",
+		.name = "empty_time",
 		.private = offsetof(struct bfq_group, stats.empty_time),
 		.seq_show = bfqg_print_stat,
 	},
 	{
-		.name = "bfq.dequeue",
+		.name = "dequeue",
 		.private = offsetof(struct bfq_group, stats.dequeue),
 		.seq_show = bfqg_print_stat,
 	},
@@ -1173,7 +1173,7 @@ struct cftype bfq_blkcg_legacy_files[] = {
 
 struct cftype bfq_blkg_files[] = {
 	{
-		.name = "bfq.weight",
+		.name = "weight",
 		.flags = CFTYPE_NOT_ON_ROOT,
 		.seq_show = bfq_io_show_weight,
 		.write = bfq_io_set_weight,
-- 
2.20.1


^ permalink raw reply	[flat|nested] 25+ messages in thread

end of thread, back to index

Thread overview: 25+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-09-09  7:31 [PATCH 0/1] block, bfq: remove bfq prefix from cgroups filenames Paolo Valente
2019-09-09  7:31 ` [PATCH 1/1] block, bfq: delete "bfq" prefix from cgroup filenames Paolo Valente
2019-09-16 14:56 ` [PATCH 0/1] block, bfq: remove bfq prefix from cgroups filenames Paolo Valente
2019-09-16 15:01   ` Jens Axboe
2019-09-16 15:07     ` Paolo Valente
2019-09-16 15:16       ` Tejun Heo
2019-09-16 15:21         ` Paolo Valente
2019-09-16 16:01           ` Jens Axboe
2019-09-16 16:45             ` Paolo Valente
  -- strict thread matches above, loose matches on Subject: below --
2019-04-08 14:39 [PATCH 0/1] bfq: remove prefixes from cgroup filenames Paolo Valente
2019-04-08 14:39 ` [PATCH 1/1] block, bfq: delete "bfq" prefix " Paolo Valente
2019-04-08 14:49   ` Johannes Thumshirn
2019-04-08 14:54     ` Paolo Valente
2019-04-08 15:01       ` Jens Axboe
2019-04-08 15:04       ` Johannes Thumshirn
2019-04-08 15:05         ` Jens Axboe
2019-04-08 15:06           ` Paolo Valente
2019-04-08 15:11             ` Jens Axboe
2019-04-08 15:15               ` Paolo Valente
2019-04-08 15:08           ` Johannes Thumshirn
2019-04-08 15:13             ` Jens Axboe
2019-04-08 15:19               ` Paolo Valente
2019-04-08 15:14             ` Paolo Valente
2019-04-08 15:17               ` Jens Axboe
2019-04-08 17:01                 ` Paolo Valente
2019-04-10 11:42           ` Ulf Hansson

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