linux-kernel - [ext3] journal commit interval

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Date:	Sun, 6 May 2007 00:29:39 +0200
From:	"Leon Woestenberg" <leon.woestenberg@...il.com>
To:	linux-kernel@...r.kernel.org
Subject: [ext3] journal commit interval

Hello all,

this is something I have long wondered about but have been afraid to ask.

When my system is chewing away on builds, the disk I/O write access
pattern of my ext3 root filesystem (using CFQ, Intel SATA controller,
hard disk) when visualized by GNOME System Monitor clearly shows a
repetitive landscape of large peaks, 5 seconds apart, which not much
activity inbetween.

I understand that's due to the ex3 journal commit interval (defaults
to 5 seconds).

But why isn't the filesystem continuously committing only that part of
the journal that is older than 5 seconds?

I would then expect the write requests to be smoothened over time,
which can only be good in terms of performance and low latency.

Regards,
-- 
Leon
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