* [PATCH 0/2] nvme-multipath: fixes for non-optimized paths
@ 2020-07-27 16:08 Hannes Reinecke
2020-07-27 16:08 ` [PATCH 1/2] nvme-multipath: fix logic " Hannes Reinecke
` (2 more replies)
0 siblings, 3 replies; 12+ messages in thread
From: Hannes Reinecke @ 2020-07-27 16:08 UTC (permalink / raw)
To: Christoph Hellwig
Cc: Hannes Reinecke, linux-nvme, Sagi Grimberg, Keith Busch, Martin Wilck
Hi all,
one of our partners informed us that the round-robin path selector
didn't do the right thing when only one optimized path (or, indeed,
none at all) are present.
These patches will fixup nvme_round_robin() to handle the case when
less than two optimized (but several non-optimized) paths are present.
These pathes are a rework of the earlier patches send by Martin Wilck.
As usual, comments and reviews are welcome.
Hannes Reinecke (1):
nvme-multipath: do not fall back to __nvme_find_path() for
non-optimized paths
Martin Wilck (1):
nvme-multipath: fix logic for non-optimized paths
drivers/nvme/host/multipath.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
--
2.16.4
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^ permalink raw reply [flat|nested] 12+ messages in thread
* [PATCH 1/2] nvme-multipath: fix logic for non-optimized paths
2020-07-27 16:08 [PATCH 0/2] nvme-multipath: fixes for non-optimized paths Hannes Reinecke
@ 2020-07-27 16:08 ` Hannes Reinecke
2020-07-27 19:42 ` Sagi Grimberg
2020-07-27 16:08 ` [PATCH 2/2] nvme-multipath: do not fall back to __nvme_find_path() " Hannes Reinecke
2020-07-28 10:51 ` [PATCH 0/2] nvme-multipath: fixes " Christoph Hellwig
2 siblings, 1 reply; 12+ messages in thread
From: Hannes Reinecke @ 2020-07-27 16:08 UTC (permalink / raw)
To: Christoph Hellwig
Cc: Hannes Reinecke, linux-nvme, Sagi Grimberg, Keith Busch, Martin Wilck
From: Martin Wilck <mwilck@suse.com>
Handle the special case where we have exactly one optimized path,
which we should keep using in this case.
Signed off-by: Martin Wilck <mwilck@suse.com>
Signed-off-by: Hannes Reinecke <hare@suse.de>
---
drivers/nvme/host/multipath.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
index 66509472fe06..fe8f7f123fac 100644
--- a/drivers/nvme/host/multipath.c
+++ b/drivers/nvme/host/multipath.c
@@ -246,6 +246,12 @@ static struct nvme_ns *nvme_round_robin_path(struct nvme_ns_head *head,
fallback = ns;
}
+ /* No optimized path found, re-check the current path */
+ if (!nvme_path_is_disabled(old) &&
+ old->ana_state == NVME_ANA_OPTIMIZED) {
+ found = old;
+ goto out;
+ }
if (!fallback)
return NULL;
found = fallback;
--
2.16.4
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^ permalink raw reply related [flat|nested] 12+ messages in thread
* [PATCH 2/2] nvme-multipath: do not fall back to __nvme_find_path() for non-optimized paths
2020-07-27 16:08 [PATCH 0/2] nvme-multipath: fixes for non-optimized paths Hannes Reinecke
2020-07-27 16:08 ` [PATCH 1/2] nvme-multipath: fix logic " Hannes Reinecke
@ 2020-07-27 16:08 ` Hannes Reinecke
2020-07-27 19:46 ` Sagi Grimberg
2020-07-28 10:51 ` [PATCH 0/2] nvme-multipath: fixes " Christoph Hellwig
2 siblings, 1 reply; 12+ messages in thread
From: Hannes Reinecke @ 2020-07-27 16:08 UTC (permalink / raw)
To: Christoph Hellwig
Cc: Hannes Reinecke, linux-nvme, Sagi Grimberg, Keith Busch, Martin Wilck
When nvme_round_robin_path() finds a valid namespace we should be using it;
falling back to __nvme_find_path() for non-optimized paths will cause the
result from nvme_round_robin_path() to be ignored for non-optimized paths.
Signed-off-by: Martin Wilck <mwilck@suse.com>
Signed-off-by: Hannes Reinecke <hare@suse.de>
---
drivers/nvme/host/multipath.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
index fe8f7f123fac..97d3c19b5684 100644
--- a/drivers/nvme/host/multipath.c
+++ b/drivers/nvme/host/multipath.c
@@ -272,8 +272,11 @@ inline struct nvme_ns *nvme_find_path(struct nvme_ns_head *head)
struct nvme_ns *ns;
ns = srcu_dereference(head->current_path[node], &head->srcu);
- if (READ_ONCE(head->subsys->iopolicy) == NVME_IOPOLICY_RR && ns)
+ if (READ_ONCE(head->subsys->iopolicy) == NVME_IOPOLICY_RR && ns) {
ns = nvme_round_robin_path(head, node, ns);
+ if (ns)
+ return ns;
+ }
if (unlikely(!ns || !nvme_path_is_optimized(ns)))
ns = __nvme_find_path(head, node);
return ns;
--
2.16.4
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^ permalink raw reply related [flat|nested] 12+ messages in thread
* Re: [PATCH 1/2] nvme-multipath: fix logic for non-optimized paths
2020-07-27 16:08 ` [PATCH 1/2] nvme-multipath: fix logic " Hannes Reinecke
@ 2020-07-27 19:42 ` Sagi Grimberg
0 siblings, 0 replies; 12+ messages in thread
From: Sagi Grimberg @ 2020-07-27 19:42 UTC (permalink / raw)
To: Hannes Reinecke, Christoph Hellwig; +Cc: linux-nvme, Martin Wilck, Keith Busch
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
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^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH 2/2] nvme-multipath: do not fall back to __nvme_find_path() for non-optimized paths
2020-07-27 16:08 ` [PATCH 2/2] nvme-multipath: do not fall back to __nvme_find_path() " Hannes Reinecke
@ 2020-07-27 19:46 ` Sagi Grimberg
2020-07-28 6:25 ` Hannes Reinecke
0 siblings, 1 reply; 12+ messages in thread
From: Sagi Grimberg @ 2020-07-27 19:46 UTC (permalink / raw)
To: Hannes Reinecke, Christoph Hellwig; +Cc: linux-nvme, Martin Wilck, Keith Busch
On 7/27/20 9:08 AM, Hannes Reinecke wrote:
> When nvme_round_robin_path() finds a valid namespace we should be using it;
> falling back to __nvme_find_path() for non-optimized paths will cause the
> result from nvme_round_robin_path() to be ignored for non-optimized paths.
>
> Signed-off-by: Martin Wilck <mwilck@suse.com>
> Signed-off-by: Hannes Reinecke <hare@suse.de>
> ---
> drivers/nvme/host/multipath.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
> index fe8f7f123fac..97d3c19b5684 100644
> --- a/drivers/nvme/host/multipath.c
> +++ b/drivers/nvme/host/multipath.c
> @@ -272,8 +272,11 @@ inline struct nvme_ns *nvme_find_path(struct nvme_ns_head *head)
> struct nvme_ns *ns;
>
> ns = srcu_dereference(head->current_path[node], &head->srcu);
> - if (READ_ONCE(head->subsys->iopolicy) == NVME_IOPOLICY_RR && ns)
> + if (READ_ONCE(head->subsys->iopolicy) == NVME_IOPOLICY_RR && ns) {
> ns = nvme_round_robin_path(head, node, ns);
> + if (ns)
> + return ns;
> + }
> if (unlikely(!ns || !nvme_path_is_optimized(ns)))
> ns = __nvme_find_path(head, node);
Maybe instead of the early return put the following condition on else?
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^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH 2/2] nvme-multipath: do not fall back to __nvme_find_path() for non-optimized paths
2020-07-27 19:46 ` Sagi Grimberg
@ 2020-07-28 6:25 ` Hannes Reinecke
2020-07-28 6:43 ` Sagi Grimberg
2020-07-28 8:02 ` Christoph Hellwig
0 siblings, 2 replies; 12+ messages in thread
From: Hannes Reinecke @ 2020-07-28 6:25 UTC (permalink / raw)
To: Sagi Grimberg, Christoph Hellwig; +Cc: linux-nvme, Martin Wilck, Keith Busch
On 7/27/20 9:46 PM, Sagi Grimberg wrote:
>
>
> On 7/27/20 9:08 AM, Hannes Reinecke wrote:
>> When nvme_round_robin_path() finds a valid namespace we should be
>> using it;
>> falling back to __nvme_find_path() for non-optimized paths will cause the
>> result from nvme_round_robin_path() to be ignored for non-optimized
>> paths.
>>
>> Signed-off-by: Martin Wilck <mwilck@suse.com>
>> Signed-off-by: Hannes Reinecke <hare@suse.de>
>> ---
>> drivers/nvme/host/multipath.c | 5 ++++-
>> 1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/nvme/host/multipath.c
>> b/drivers/nvme/host/multipath.c
>> index fe8f7f123fac..97d3c19b5684 100644
>> --- a/drivers/nvme/host/multipath.c
>> +++ b/drivers/nvme/host/multipath.c
>> @@ -272,8 +272,11 @@ inline struct nvme_ns *nvme_find_path(struct
>> nvme_ns_head *head)
>> struct nvme_ns *ns;
>> ns = srcu_dereference(head->current_path[node], &head->srcu);
>> - if (READ_ONCE(head->subsys->iopolicy) == NVME_IOPOLICY_RR && ns)
>> + if (READ_ONCE(head->subsys->iopolicy) == NVME_IOPOLICY_RR && ns) {
>> ns = nvme_round_robin_path(head, node, ns);
>> + if (ns)
>> + return ns;
>> + }
>> if (unlikely(!ns || !nvme_path_is_optimized(ns)))
>> ns = __nvme_find_path(head, node);
>
> Maybe instead of the early return put the following condition on else?
That depends on whether we want to have a fallback to __nvme_find_path()
or not. With your suggestion we would lose that; I'd rather keep it.
Cheers,
Hannes
--
Dr. Hannes Reinecke Teamlead Storage & Networking
hare@suse.de +49 911 74053 688
SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), Geschäftsführer: Felix Imendörffer
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^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH 2/2] nvme-multipath: do not fall back to __nvme_find_path() for non-optimized paths
2020-07-28 6:25 ` Hannes Reinecke
@ 2020-07-28 6:43 ` Sagi Grimberg
2020-07-28 8:02 ` Christoph Hellwig
1 sibling, 0 replies; 12+ messages in thread
From: Sagi Grimberg @ 2020-07-28 6:43 UTC (permalink / raw)
To: Hannes Reinecke, Christoph Hellwig; +Cc: linux-nvme, Martin Wilck, Keith Busch
>>> When nvme_round_robin_path() finds a valid namespace we should be
>>> using it;
>>> falling back to __nvme_find_path() for non-optimized paths will cause
>>> the
>>> result from nvme_round_robin_path() to be ignored for non-optimized
>>> paths.
>>>
>>> Signed-off-by: Martin Wilck <mwilck@suse.com>
>>> Signed-off-by: Hannes Reinecke <hare@suse.de>
>>> ---
>>> drivers/nvme/host/multipath.c | 5 ++++-
>>> 1 file changed, 4 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/nvme/host/multipath.c
>>> b/drivers/nvme/host/multipath.c
>>> index fe8f7f123fac..97d3c19b5684 100644
>>> --- a/drivers/nvme/host/multipath.c
>>> +++ b/drivers/nvme/host/multipath.c
>>> @@ -272,8 +272,11 @@ inline struct nvme_ns *nvme_find_path(struct
>>> nvme_ns_head *head)
>>> struct nvme_ns *ns;
>>> ns = srcu_dereference(head->current_path[node], &head->srcu);
>>> - if (READ_ONCE(head->subsys->iopolicy) == NVME_IOPOLICY_RR && ns)
>>> + if (READ_ONCE(head->subsys->iopolicy) == NVME_IOPOLICY_RR && ns) {
>>> ns = nvme_round_robin_path(head, node, ns);
>>> + if (ns)
>>> + return ns;
>>> + }
>>> if (unlikely(!ns || !nvme_path_is_optimized(ns)))
>>> ns = __nvme_find_path(head, node);
>>
>> Maybe instead of the early return put the following condition on else?
>
> That depends on whether we want to have a fallback to __nvme_find_path()
> or not. With your suggestion we would lose that; I'd rather keep it.
OK...
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
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^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH 2/2] nvme-multipath: do not fall back to __nvme_find_path() for non-optimized paths
2020-07-28 6:25 ` Hannes Reinecke
2020-07-28 6:43 ` Sagi Grimberg
@ 2020-07-28 8:02 ` Christoph Hellwig
2020-07-28 8:14 ` Hannes Reinecke
1 sibling, 1 reply; 12+ messages in thread
From: Christoph Hellwig @ 2020-07-28 8:02 UTC (permalink / raw)
To: Hannes Reinecke
Cc: Martin Wilck, linux-nvme, Sagi Grimberg, Keith Busch, Christoph Hellwig
On Tue, Jul 28, 2020 at 08:25:18AM +0200, Hannes Reinecke wrote:
>> Maybe instead of the early return put the following condition on else?
>
> That depends on whether we want to have a fallback to __nvme_find_path() or
> not. With your suggestion we would lose that; I'd rather keep it.
Why would we want to fall back? nvme_round_robin_path only
returns NULL in case there is a single disabled path, in which
case __nvme_find_path won't find anything either. I'd go for something
like this:
---
From 4f578364a3d15898c7d715315a3371b2f71db416 Mon Sep 17 00:00:00 2001
From: Hannes Reinecke <hare@suse.de>
Date: Mon, 27 Jul 2020 18:08:03 +0200
Subject: nvme-multipath: do not fall back to __nvme_find_path() for
non-optimized paths
When nvme_round_robin_path() finds a valid namespace we should be using it;
falling back to __nvme_find_path() for non-optimized paths will cause the
result from nvme_round_robin_path() to be ignored for non-optimized paths.
Signed-off-by: Martin Wilck <mwilck@suse.com>
Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
drivers/nvme/host/multipath.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
index 93c70e1591de8f..3ded54d2c9c6ad 100644
--- a/drivers/nvme/host/multipath.c
+++ b/drivers/nvme/host/multipath.c
@@ -281,10 +281,13 @@ inline struct nvme_ns *nvme_find_path(struct nvme_ns_head *head)
struct nvme_ns *ns;
ns = srcu_dereference(head->current_path[node], &head->srcu);
- if (READ_ONCE(head->subsys->iopolicy) == NVME_IOPOLICY_RR && ns)
- ns = nvme_round_robin_path(head, node, ns);
- if (unlikely(!ns || !nvme_path_is_optimized(ns)))
- ns = __nvme_find_path(head, node);
+ if (unlikely(!ns))
+ return __nvme_find_path(head, node);
+
+ if (READ_ONCE(head->subsys->iopolicy) == NVME_IOPOLICY_RR)
+ return nvme_round_robin_path(head, node, ns);
+ if (unlikely(!nvme_path_is_optimized(ns)))
+ return __nvme_find_path(head, node);
return ns;
}
--
2.27.0
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^ permalink raw reply related [flat|nested] 12+ messages in thread
* Re: [PATCH 2/2] nvme-multipath: do not fall back to __nvme_find_path() for non-optimized paths
2020-07-28 8:02 ` Christoph Hellwig
@ 2020-07-28 8:14 ` Hannes Reinecke
2020-07-28 8:16 ` Christoph Hellwig
0 siblings, 1 reply; 12+ messages in thread
From: Hannes Reinecke @ 2020-07-28 8:14 UTC (permalink / raw)
To: Christoph Hellwig; +Cc: linux-nvme, Sagi Grimberg, Keith Busch, Martin Wilck
On 7/28/20 10:02 AM, Christoph Hellwig wrote:
> On Tue, Jul 28, 2020 at 08:25:18AM +0200, Hannes Reinecke wrote:
>>> Maybe instead of the early return put the following condition on else?
>>
>> That depends on whether we want to have a fallback to __nvme_find_path() or
>> not. With your suggestion we would lose that; I'd rather keep it.
>
> Why would we want to fall back? nvme_round_robin_path only
> returns NULL in case there is a single disabled path, in which
> case __nvme_find_path won't find anything either. I'd go for something
> like this:
>
> ---
> From 4f578364a3d15898c7d715315a3371b2f71db416 Mon Sep 17 00:00:00 2001
> From: Hannes Reinecke <hare@suse.de>
> Date: Mon, 27 Jul 2020 18:08:03 +0200
> Subject: nvme-multipath: do not fall back to __nvme_find_path() for
> non-optimized paths
>
> When nvme_round_robin_path() finds a valid namespace we should be using it;
> falling back to __nvme_find_path() for non-optimized paths will cause the
> result from nvme_round_robin_path() to be ignored for non-optimized paths.
>
> Signed-off-by: Martin Wilck <mwilck@suse.com>
> Signed-off-by: Hannes Reinecke <hare@suse.de>
> Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
> drivers/nvme/host/multipath.c | 11 +++++++----
> 1 file changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
> index 93c70e1591de8f..3ded54d2c9c6ad 100644
> --- a/drivers/nvme/host/multipath.c
> +++ b/drivers/nvme/host/multipath.c
> @@ -281,10 +281,13 @@ inline struct nvme_ns *nvme_find_path(struct nvme_ns_head *head)
> struct nvme_ns *ns;
>
> ns = srcu_dereference(head->current_path[node], &head->srcu);
> - if (READ_ONCE(head->subsys->iopolicy) == NVME_IOPOLICY_RR && ns)
> - ns = nvme_round_robin_path(head, node, ns);
> - if (unlikely(!ns || !nvme_path_is_optimized(ns)))
> - ns = __nvme_find_path(head, node);
> + if (unlikely(!ns))
> + return __nvme_find_path(head, node);
> +
> + if (READ_ONCE(head->subsys->iopolicy) == NVME_IOPOLICY_RR)
> + return nvme_round_robin_path(head, node, ns);
> + if (unlikely(!nvme_path_is_optimized(ns)))
> + return __nvme_find_path(head, node);
> return ns;
> }
>
>
Yes, that would work, too.
Should I resend?
Cheers,
Hannes
--
Dr. Hannes Reinecke Kernel Storage Architect
hare@suse.de +49 911 74053 688
SUSE Software Solutions Germany GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), GF: Felix Imendörffer
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^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH 2/2] nvme-multipath: do not fall back to __nvme_find_path() for non-optimized paths
2020-07-28 8:14 ` Hannes Reinecke
@ 2020-07-28 8:16 ` Christoph Hellwig
2020-07-28 8:18 ` Hannes Reinecke
0 siblings, 1 reply; 12+ messages in thread
From: Christoph Hellwig @ 2020-07-28 8:16 UTC (permalink / raw)
To: Hannes Reinecke
Cc: Martin Wilck, linux-nvme, Christoph Hellwig, Keith Busch, Sagi Grimberg
On Tue, Jul 28, 2020 at 10:14:14AM +0200, Hannes Reinecke wrote:
> On 7/28/20 10:02 AM, Christoph Hellwig wrote:
> > On Tue, Jul 28, 2020 at 08:25:18AM +0200, Hannes Reinecke wrote:
> >>> Maybe instead of the early return put the following condition on else?
> >>
> >> That depends on whether we want to have a fallback to __nvme_find_path() or
> >> not. With your suggestion we would lose that; I'd rather keep it.
> >
> > Why would we want to fall back? nvme_round_robin_path only
> > returns NULL in case there is a single disabled path, in which
> > case __nvme_find_path won't find anything either. I'd go for something
> > like this:
> >
> > ---
> > From 4f578364a3d15898c7d715315a3371b2f71db416 Mon Sep 17 00:00:00 2001
> > From: Hannes Reinecke <hare@suse.de>
> > Date: Mon, 27 Jul 2020 18:08:03 +0200
> > Subject: nvme-multipath: do not fall back to __nvme_find_path() for
> > non-optimized paths
> >
> > When nvme_round_robin_path() finds a valid namespace we should be using it;
> > falling back to __nvme_find_path() for non-optimized paths will cause the
> > result from nvme_round_robin_path() to be ignored for non-optimized paths.
> >
> > Signed-off-by: Martin Wilck <mwilck@suse.com>
> > Signed-off-by: Hannes Reinecke <hare@suse.de>
> > Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
> > Signed-off-by: Christoph Hellwig <hch@lst.de>
> > ---
> > drivers/nvme/host/multipath.c | 11 +++++++----
> > 1 file changed, 7 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
> > index 93c70e1591de8f..3ded54d2c9c6ad 100644
> > --- a/drivers/nvme/host/multipath.c
> > +++ b/drivers/nvme/host/multipath.c
> > @@ -281,10 +281,13 @@ inline struct nvme_ns *nvme_find_path(struct nvme_ns_head *head)
> > struct nvme_ns *ns;
> >
> > ns = srcu_dereference(head->current_path[node], &head->srcu);
> > - if (READ_ONCE(head->subsys->iopolicy) == NVME_IOPOLICY_RR && ns)
> > - ns = nvme_round_robin_path(head, node, ns);
> > - if (unlikely(!ns || !nvme_path_is_optimized(ns)))
> > - ns = __nvme_find_path(head, node);
> > + if (unlikely(!ns))
> > + return __nvme_find_path(head, node);
> > +
> > + if (READ_ONCE(head->subsys->iopolicy) == NVME_IOPOLICY_RR)
> > + return nvme_round_robin_path(head, node, ns);
> > + if (unlikely(!nvme_path_is_optimized(ns)))
> > + return __nvme_find_path(head, node);
> > return ns;
> > }
> >
> >
>
> Yes, that would work, too.
>
> Should I resend?
No need, I can apply it with the modification. But if you have a
RR test setup it would be great to run it through that again, just in
case.
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^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH 2/2] nvme-multipath: do not fall back to __nvme_find_path() for non-optimized paths
2020-07-28 8:16 ` Christoph Hellwig
@ 2020-07-28 8:18 ` Hannes Reinecke
0 siblings, 0 replies; 12+ messages in thread
From: Hannes Reinecke @ 2020-07-28 8:18 UTC (permalink / raw)
To: Christoph Hellwig; +Cc: linux-nvme, Sagi Grimberg, Keith Busch, Martin Wilck
On 7/28/20 10:16 AM, Christoph Hellwig wrote:
> On Tue, Jul 28, 2020 at 10:14:14AM +0200, Hannes Reinecke wrote:
>> On 7/28/20 10:02 AM, Christoph Hellwig wrote:
>>> On Tue, Jul 28, 2020 at 08:25:18AM +0200, Hannes Reinecke wrote:
>>>>> Maybe instead of the early return put the following condition on else?
>>>>
>>>> That depends on whether we want to have a fallback to __nvme_find_path() or
>>>> not. With your suggestion we would lose that; I'd rather keep it.
>>>
>>> Why would we want to fall back? nvme_round_robin_path only
>>> returns NULL in case there is a single disabled path, in which
>>> case __nvme_find_path won't find anything either. I'd go for something
>>> like this:
>>>
>>> ---
>>> From 4f578364a3d15898c7d715315a3371b2f71db416 Mon Sep 17 00:00:00 2001
>>> From: Hannes Reinecke <hare@suse.de>
>>> Date: Mon, 27 Jul 2020 18:08:03 +0200
>>> Subject: nvme-multipath: do not fall back to __nvme_find_path() for
>>> non-optimized paths
>>>
>>> When nvme_round_robin_path() finds a valid namespace we should be using it;
>>> falling back to __nvme_find_path() for non-optimized paths will cause the
>>> result from nvme_round_robin_path() to be ignored for non-optimized paths.
>>>
>>> Signed-off-by: Martin Wilck <mwilck@suse.com>
>>> Signed-off-by: Hannes Reinecke <hare@suse.de>
>>> Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
>>> Signed-off-by: Christoph Hellwig <hch@lst.de>
>>> ---
>>> drivers/nvme/host/multipath.c | 11 +++++++----
>>> 1 file changed, 7 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
>>> index 93c70e1591de8f..3ded54d2c9c6ad 100644
>>> --- a/drivers/nvme/host/multipath.c
>>> +++ b/drivers/nvme/host/multipath.c
>>> @@ -281,10 +281,13 @@ inline struct nvme_ns *nvme_find_path(struct nvme_ns_head *head)
>>> struct nvme_ns *ns;
>>>
>>> ns = srcu_dereference(head->current_path[node], &head->srcu);
>>> - if (READ_ONCE(head->subsys->iopolicy) == NVME_IOPOLICY_RR && ns)
>>> - ns = nvme_round_robin_path(head, node, ns);
>>> - if (unlikely(!ns || !nvme_path_is_optimized(ns)))
>>> - ns = __nvme_find_path(head, node);
>>> + if (unlikely(!ns))
>>> + return __nvme_find_path(head, node);
>>> +
>>> + if (READ_ONCE(head->subsys->iopolicy) == NVME_IOPOLICY_RR)
>>> + return nvme_round_robin_path(head, node, ns);
>>> + if (unlikely(!nvme_path_is_optimized(ns)))
>>> + return __nvme_find_path(head, node);
>>> return ns;
>>> }
>>>
>>>
>>
>> Yes, that would work, too.
>>
>> Should I resend?
>
> No need, I can apply it with the modification. But if you have a
> RR test setup it would be great to run it through that again, just in
> case.
>
I'm at it.
Cheers,
Hannes
--
Dr. Hannes Reinecke Kernel Storage Architect
hare@suse.de +49 911 74053 688
SUSE Software Solutions Germany GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), GF: Felix Imendörffer
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^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH 0/2] nvme-multipath: fixes for non-optimized paths
2020-07-27 16:08 [PATCH 0/2] nvme-multipath: fixes for non-optimized paths Hannes Reinecke
2020-07-27 16:08 ` [PATCH 1/2] nvme-multipath: fix logic " Hannes Reinecke
2020-07-27 16:08 ` [PATCH 2/2] nvme-multipath: do not fall back to __nvme_find_path() " Hannes Reinecke
@ 2020-07-28 10:51 ` Christoph Hellwig
2 siblings, 0 replies; 12+ messages in thread
From: Christoph Hellwig @ 2020-07-28 10:51 UTC (permalink / raw)
To: Hannes Reinecke
Cc: Martin Wilck, linux-nvme, Christoph Hellwig, Keith Busch, Sagi Grimberg
Applied to nvme-5.9 with the tweak discussed earlier.
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^ permalink raw reply [flat|nested] 12+ messages in thread
end of thread, other threads:[~2020-07-28 10:51 UTC | newest]
Thread overview: 12+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-07-27 16:08 [PATCH 0/2] nvme-multipath: fixes for non-optimized paths Hannes Reinecke
2020-07-27 16:08 ` [PATCH 1/2] nvme-multipath: fix logic " Hannes Reinecke
2020-07-27 19:42 ` Sagi Grimberg
2020-07-27 16:08 ` [PATCH 2/2] nvme-multipath: do not fall back to __nvme_find_path() " Hannes Reinecke
2020-07-27 19:46 ` Sagi Grimberg
2020-07-28 6:25 ` Hannes Reinecke
2020-07-28 6:43 ` Sagi Grimberg
2020-07-28 8:02 ` Christoph Hellwig
2020-07-28 8:14 ` Hannes Reinecke
2020-07-28 8:16 ` Christoph Hellwig
2020-07-28 8:18 ` Hannes Reinecke
2020-07-28 10:51 ` [PATCH 0/2] nvme-multipath: fixes " Christoph Hellwig
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