Re: kupdate weirdness

From: David Chinner
Date: Wed Aug 01 2007 - 21:54:07 EST


On Wed, Aug 01, 2007 at 10:45:16PM +0200, Miklos Szeredi wrote:
> The following strange behavior can be observed:
>
> 1. large file is written
> 2. after 30 seconds, nr_dirty goes down by 1024
> 3. then for some time (< 30 sec) nothing happens (disk idle)
> 4. then nr_dirty again goes down by 1024
> 5. repeat from 3. until whole file is written
>
> So basically a 4Mbyte chunk of the file is written every 30 seconds.
> I'm quite sure this is not the intended behavior.
>
> The reason seems to be that __sync_single_inode() will move the
> partially written inode from s_io onto s_dirty, and sync_sb_inode()
> will not splice it back onto s_io until the rest of the inodes on s_io
> has been processed.

It's been doing this for a long time.

http://marc.info/?l=linux-kernel&m=113919849421679&w=2

Cheers,

Dave.
--
Dave Chinner
Principal Engineer
SGI Australian Software Group
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