diff options
| author | Sergey Senozhatsky <sergey.senozhatsky@gmail.com> | 2014-10-09 15:29:57 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-10-09 22:26:03 -0400 |
| commit | 015254daf1753003c19c46b90ee85a963260d270 (patch) | |
| tree | 38a23db2944bfd144d2437bfe09f7c19a386dc45 /Documentation | |
| parent | 461a8eee6af3b55745be64bea403ed0b743563cf (diff) | |
zram: use notify_free to account all free notifications
`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>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-block-zram | 13 |
1 files changed, 8 insertions, 5 deletions
diff --git a/Documentation/ABI/testing/sysfs-block-zram b/Documentation/ABI/testing/sysfs-block-zram index b13dc993291f..a6148eaf91e5 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 |