From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753700AbaIOOuI (ORCPT ); Mon, 15 Sep 2014 10:50:08 -0400 Received: from mail-pd0-f180.google.com ([209.85.192.180]:60936 "EHLO mail-pd0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752279AbaIOOuB (ORCPT ); Mon, 15 Sep 2014 10:50:01 -0400 From: Sergey Senozhatsky To: Andrew Morton Cc: Minchan Kim , Jerome Marchand , Nitin Gupta , Chao Yu , linux-kernel@vger.kernel.org, Sergey Senozhatsky Subject: [PATCHv3] zram: use notify_free to account all free notifications Date: Mon, 15 Sep 2014 23:49:28 +0900 Message-Id: <1410792568-31539-2-git-send-email-sergey.senozhatsky@gmail.com> X-Mailer: git-send-email 2.1.0.350.g8b25fe0 In-Reply-To: <1410792568-31539-1-git-send-email-sergey.senozhatsky@gmail.com> References: <1410792568-31539-1-git-send-email-sergey.senozhatsky@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org `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 --- 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/notify_free Date: August 2010 Contact: Nitin Gupta 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/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