From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f71.google.com (mail-pg0-f71.google.com [74.125.83.71]) by kanga.kvack.org (Postfix) with ESMTP id D0A346B0003 for ; Mon, 18 Jun 2018 19:59:51 -0400 (EDT) Received: by mail-pg0-f71.google.com with SMTP id d10-v6so5658374pgv.8 for ; Mon, 18 Jun 2018 16:59:51 -0700 (PDT) Received: from out4436.biz.mail.alibaba.com (out4436.biz.mail.alibaba.com. [47.88.44.36]) by mx.google.com with ESMTPS id v18-v6si16046824plo.285.2018.06.18.16.59.47 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 18 Jun 2018 16:59:49 -0700 (PDT) From: Yang Shi Subject: [PATCH v2] doc: add description to dirtytime_expire_seconds Date: Tue, 19 Jun 2018 07:59:18 +0800 Message-Id: <1529366358-67312-1-git-send-email-yang.shi@linux.alibaba.com> Sender: owner-linux-mm@kvack.org List-ID: To: tytso@mit.edu, nborisov@suse.com, corbet@lwn.net, akpm@linux-foundation.org Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org commit 1efff914afac8a965ad63817ecf8861a927c2ace ("fs: add dirtytime_expire_seconds sysctl") introduced dirtytime_expire_seconds knob, but there is not description about it in Documentation/sysctl/vm.txt. Add the description for it. Cc: Theodore Ts'o Signed-off-by: Yang Shi --- v1 --> v2: Rephrased the description per Nikolay Borisov's comment I didn't dig into the old review discussion about why the description was not added at the first place. I'm supposed every knob under /proc/sys should have a brief description. Documentation/sysctl/vm.txt | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt index 17256f2..b078baf 100644 --- a/Documentation/sysctl/vm.txt +++ b/Documentation/sysctl/vm.txt @@ -27,6 +27,7 @@ Currently, these files are in /proc/sys/vm: - dirty_bytes - dirty_expire_centisecs - dirty_ratio +- dirtytime_expire_seconds - dirty_writeback_centisecs - drop_caches - extfrag_threshold @@ -178,6 +179,18 @@ The total available memory is not equal to total system memory. ============================================================== +dirtytime_expire_seconds + +When a lazytime inode is constantly having its pages dirtied, the inode with +an updated timestamp will never get chance to be written out. And, if the +only thing that has happened on the file system is a dirtytime inode caused +by an atime update, a worker will be scheduled to make sure that inode +eventually gets pushed out to disk. This tunable is used to define when dirty +inode is old enough to be eligible for writeback by the kernel flusher threads. +And, it is also used as the interval to wakeup dirtytime_writeback thread. + +============================================================== + dirty_writeback_centisecs The kernel flusher threads will periodically wake up and write `old' data -- 1.8.3.1