* [PATCHv3] zram: use notify_free to account all free notifications
@ 2014-09-15 14:49 Sergey Senozhatsky
2014-09-15 14:49 ` Sergey Senozhatsky
0 siblings, 1 reply; 4+ messages in thread
From: Sergey Senozhatsky @ 2014-09-15 14:49 UTC (permalink / raw)
To: Andrew Morton
Cc: Minchan Kim, Jerome Marchand, Nitin Gupta, Chao Yu, linux-kernel,
Sergey Senozhatsky
Hello,
This patch change the way zram uses `notify_free' stat attr. Currently,
this attr accounts only swap free notifications, iow used only when zram
device is a swap device. The patch preserves the existing behaviour and
additionally makes `notify_free' universal, so it's also used by zram to
account REQ_DISCARDs when zram is not used as a swap device.
Please refer to:
https://lkml.org/lkml/2014/9/3/1115
V3:
-- account all notifications, including those that hit ZRAM_ZERO page
V2:
-- fix accounting error found by Minchan Kim.
Sergey Senozhatsky (1):
zram: use notify_free to account all free notifications
Documentation/ABI/testing/sysfs-block-zram | 13 ++++++++-----
drivers/block/zram/zram_drv.c | 1 +
2 files changed, 9 insertions(+), 5 deletions(-)
--
2.1.0.350.g8b25fe0
^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCHv3] zram: use notify_free to account all free notifications
2014-09-15 14:49 [PATCHv3] zram: use notify_free to account all free notifications Sergey Senozhatsky
@ 2014-09-15 14:49 ` Sergey Senozhatsky
2014-09-15 23:03 ` Minchan Kim
2014-09-17 8:19 ` Jerome Marchand
0 siblings, 2 replies; 4+ messages in thread
From: Sergey Senozhatsky @ 2014-09-15 14:49 UTC (permalink / raw)
To: Andrew Morton
Cc: Minchan Kim, Jerome Marchand, Nitin Gupta, Chao Yu, linux-kernel,
Sergey Senozhatsky
`notify_free' device attribute accounts the number of slot free notifications
and internally represents the number of zram_free_page() calls. Slot free
notifications are sent only when device is used as a swap device, hence
`notify_free' is used only for swap devices. Since f4659d8e620d08 (zram:
support REQ_DISCARD) ZRAM handles yet another one free notification (also
via zram_free_page() call) -- REQ_DISCARD requests, which are sent by a
filesystem, whenever some data blocks are discarded. However, there is no
way to know the number of notifications in the latter case.
Use `notify_free' to account the number of pages freed by zram_bio_discard()
and zram_slot_free_notify(). Depending on usage scenario `notify_free'
represents:
a) the number of pages freed because of slot free notifications, which is
equal to the number of swap_slot_free_notify() calls, so there is no
behaviour change
b) the number of pages freed because of REQ_DISCARD notifications
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
---
Documentation/ABI/testing/sysfs-block-zram | 13 ++++++++-----
drivers/block/zram/zram_drv.c | 1 +
2 files changed, 9 insertions(+), 5 deletions(-)
diff --git a/Documentation/ABI/testing/sysfs-block-zram b/Documentation/ABI/testing/sysfs-block-zram
index b13dc99..a6148ea 100644
--- a/Documentation/ABI/testing/sysfs-block-zram
+++ b/Documentation/ABI/testing/sysfs-block-zram
@@ -77,11 +77,14 @@ What: /sys/block/zram<id>/notify_free
Date: August 2010
Contact: Nitin Gupta <ngupta@vflare.org>
Description:
- The notify_free file is read-only and specifies the number of
- swap slot free notifications received by this device. These
- notifications are sent to a swap block device when a swap slot
- is freed. This statistic is applicable only when this disk is
- being used as a swap disk.
+ The notify_free file is read-only. Depending on device usage
+ scenario it may account a) the number of pages freed because
+ of swap slot free notifications or b) the number of pages freed
+ because of REQ_DISCARD requests sent by bio. The former ones
+ are sent to a swap block device when a swap slot is freed, which
+ implies that this disk is being used as a swap disk. The latter
+ ones are sent by filesystem mounted with discard option,
+ whenever some data blocks are getting discarded.
What: /sys/block/zram<id>/zero_pages
Date: August 2010
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index d78b245..3b85016 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -698,6 +698,7 @@ static void zram_bio_discard(struct zram *zram, u32 index,
bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
zram_free_page(zram, index);
bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
+ atomic64_inc(&zram->stats.notify_free);
index++;
n -= PAGE_SIZE;
}
--
2.1.0.350.g8b25fe0
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCHv3] zram: use notify_free to account all free notifications
2014-09-15 14:49 ` Sergey Senozhatsky
@ 2014-09-15 23:03 ` Minchan Kim
2014-09-17 8:19 ` Jerome Marchand
1 sibling, 0 replies; 4+ messages in thread
From: Minchan Kim @ 2014-09-15 23:03 UTC (permalink / raw)
To: Sergey Senozhatsky
Cc: Andrew Morton, Jerome Marchand, Nitin Gupta, Chao Yu, linux-kernel
On Mon, Sep 15, 2014 at 11:49:28PM +0900, Sergey Senozhatsky wrote:
> `notify_free' device attribute accounts the number of slot free notifications
> and internally represents the number of zram_free_page() calls. Slot free
> notifications are sent only when device is used as a swap device, hence
> `notify_free' is used only for swap devices. Since f4659d8e620d08 (zram:
> support REQ_DISCARD) ZRAM handles yet another one free notification (also
> via zram_free_page() call) -- REQ_DISCARD requests, which are sent by a
> filesystem, whenever some data blocks are discarded. However, there is no
> way to know the number of notifications in the latter case.
>
> Use `notify_free' to account the number of pages freed by zram_bio_discard()
> and zram_slot_free_notify(). Depending on usage scenario `notify_free'
> represents:
> a) the number of pages freed because of slot free notifications, which is
> equal to the number of swap_slot_free_notify() calls, so there is no
> behaviour change
>
> b) the number of pages freed because of REQ_DISCARD notifications
>
> Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Thanks a lot!
--
Kind regards,
Minchan Kim
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCHv3] zram: use notify_free to account all free notifications
2014-09-15 14:49 ` Sergey Senozhatsky
2014-09-15 23:03 ` Minchan Kim
@ 2014-09-17 8:19 ` Jerome Marchand
1 sibling, 0 replies; 4+ messages in thread
From: Jerome Marchand @ 2014-09-17 8:19 UTC (permalink / raw)
To: Sergey Senozhatsky, Andrew Morton
Cc: Minchan Kim, Nitin Gupta, Chao Yu, linux-kernel
[-- Attachment #1: Type: text/plain, Size: 3204 bytes --]
On 09/15/2014 04:49 PM, Sergey Senozhatsky wrote:
> `notify_free' device attribute accounts the number of slot free notifications
> and internally represents the number of zram_free_page() calls. Slot free
> notifications are sent only when device is used as a swap device, hence
> `notify_free' is used only for swap devices. Since f4659d8e620d08 (zram:
> support REQ_DISCARD) ZRAM handles yet another one free notification (also
> via zram_free_page() call) -- REQ_DISCARD requests, which are sent by a
> filesystem, whenever some data blocks are discarded. However, there is no
> way to know the number of notifications in the latter case.
>
> Use `notify_free' to account the number of pages freed by zram_bio_discard()
> and zram_slot_free_notify(). Depending on usage scenario `notify_free'
> represents:
> a) the number of pages freed because of slot free notifications, which is
> equal to the number of swap_slot_free_notify() calls, so there is no
> behaviour change
>
> b) the number of pages freed because of REQ_DISCARD notifications
>
> Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
> ---
> Documentation/ABI/testing/sysfs-block-zram | 13 ++++++++-----
> drivers/block/zram/zram_drv.c | 1 +
> 2 files changed, 9 insertions(+), 5 deletions(-)
>
> diff --git a/Documentation/ABI/testing/sysfs-block-zram b/Documentation/ABI/testing/sysfs-block-zram
> index b13dc99..a6148ea 100644
> --- a/Documentation/ABI/testing/sysfs-block-zram
> +++ b/Documentation/ABI/testing/sysfs-block-zram
> @@ -77,11 +77,14 @@ What: /sys/block/zram<id>/notify_free
> Date: August 2010
> Contact: Nitin Gupta <ngupta@vflare.org>
> Description:
> - The notify_free file is read-only and specifies the number of
> - swap slot free notifications received by this device. These
> - notifications are sent to a swap block device when a swap slot
> - is freed. This statistic is applicable only when this disk is
> - being used as a swap disk.
> + The notify_free file is read-only. Depending on device usage
> + scenario it may account a) the number of pages freed because
> + of swap slot free notifications or b) the number of pages freed
> + because of REQ_DISCARD requests sent by bio. The former ones
> + are sent to a swap block device when a swap slot is freed, which
> + implies that this disk is being used as a swap disk. The latter
> + ones are sent by filesystem mounted with discard option,
> + whenever some data blocks are getting discarded.
>
> What: /sys/block/zram<id>/zero_pages
> Date: August 2010
> diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
> index d78b245..3b85016 100644
> --- a/drivers/block/zram/zram_drv.c
> +++ b/drivers/block/zram/zram_drv.c
> @@ -698,6 +698,7 @@ static void zram_bio_discard(struct zram *zram, u32 index,
> bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
> zram_free_page(zram, index);
> bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
> + atomic64_inc(&zram->stats.notify_free);
> index++;
> n -= PAGE_SIZE;
> }
>
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2014-09-15 14:49 [PATCHv3] zram: use notify_free to account all free notifications Sergey Senozhatsky
2014-09-15 14:49 ` Sergey Senozhatsky
2014-09-15 23:03 ` Minchan Kim
2014-09-17 8:19 ` Jerome Marchand
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