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Date: Mon, 15 Sep 2014 23:49:28 +0900 From: Sergey Senozhatsky <sergey.senozhatsky@...il.com> To: Andrew Morton <akpm@...ux-foundation.org> Cc: Minchan Kim <minchan@...nel.org>, Jerome Marchand <jmarchan@...hat.com>, Nitin Gupta <ngupta@...are.org>, Chao Yu <chao2.yu@...sung.com>, linux-kernel@...r.kernel.org, Sergey Senozhatsky <sergey.senozhatsky@...il.com> Subject: [PATCHv3] 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@...il.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@...are.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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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