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 <[email protected]>
Acked-by: Jerome Marchand <[email protected]> > --- > 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 <[email protected]> > 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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