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Message-ID: <532480950801172351p7603e8d0icdc8e2b27c1e0051@mail.gmail.com>
Date: Thu, 17 Jan 2008 23:51:51 -0800
From: "Michael Rubin" <mrubin@google.com>
To: "Fengguang Wu" <wfg@mail.ustc.edu.cn>
Subject: Re: [PATCH 00/13] writeback bug fixes and simplifications take 2
Cc: "Andrew Morton" <akpm@osdl.org>, "Peter Zijlstra" <peterz@infradead.org>,
       linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
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On Jan 15, 2008 4:36 AM, Fengguang Wu <wfg@mail.ustc.edu.cn> wrote:
> Andrew,
>
> This patchset mainly polishes the writeback queuing policies.
> The main goals are:
>
> (1) small files should not be starved by big dirty files
> (2) sync as fast as possible for not-blocked inodes/pages
>     - don't leave them out; no congestion_wait() in between them
> (3) avoid busy iowait for blocked inodes
>     - retry them in the next go of s_io(maybe at the next wakeup of pdflush)
>
> The role of the queues:
>
> s_dirty:   park for dirtied_when expiration
> s_io:      park for io submission
> s_more_io: for big dirty inodes, they will be retried in this run of pdflush
>            (it ensures fairness between small/large files)
> s_more_io_wait: for blocked inodes, they will be picked up in next run of s_io

Quick question to make sure I get this. Each queue is sorted as such:

s_dirty - sorted by the dirtied_when field
s_io - sorted by  no explicit key but by the order we want to process
in sync_sb_inodes
s_more_io - held for later they are sorted in the same manner as s_io

Is that it?

mrubin
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