Commit 015254da authored by Sergey Senozhatsky's avatar Sergey Senozhatsky Committed by Linus Torvalds

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
f4659d8e (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: default avatarSergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: default avatarMinchan Kim <minchan@kernel.org>
Acked-by: default avatarJerome Marchand <jmarchan@redhat.com>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 461a8eee
......@@ -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
......
......@@ -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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