Hey Sergey, Sorry for late review.
On Fri, Sep 05, 2014 at 09:57:09PM +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 in zram_free_page(), > instead of accounting only swap_slot_free_notify() calls (each > zram_slot_free_notify() call frees one page). > > This means that 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]> > --- > Documentation/ABI/testing/sysfs-block-zram | 13 ++++++++----- > drivers/block/zram/zram_drv.c | 2 +- > 2 files changed, 9 insertions(+), 6 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..bc20fe1 100644 > --- a/drivers/block/zram/zram_drv.c > +++ b/drivers/block/zram/zram_drv.c > @@ -410,6 +410,7 @@ static void zram_free_page(struct zram *zram, size_t > index) > atomic64_sub(zram_get_obj_size(meta, index), > &zram->stats.compr_data_size); > atomic64_dec(&zram->stats.pages_stored); > + atomic64_inc(&zram->stats.notify_free); It is wrong. The zram_free_page is called at several places and they are all not notify free. Pz, account it in zram_slot_free_notify and zram_bio_discard. > > meta->table[index].handle = 0; > zram_set_obj_size(meta, index, 0); > @@ -938,7 +939,6 @@ static void zram_slot_free_notify(struct block_device > *bdev, > 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); > } > > static const struct block_device_operations zram_devops = { > -- > 2.1.0.134.gb1ae451 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to [email protected] > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- Kind regards, Minchan Kim -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
