Re: [PATCH 6/6] writeback: refill b_io iff empty

From: Jan Kara
Date: Thu May 05 2011 - 12:37:26 EST


On Wed 04-05-11 15:39:31, Wu Fengguang wrote:
> To help understand the behavior change, I wrote the writeback_queue_io
> trace event, and found very different patterns between
> - vanilla kernel
> - this patchset plus the sync livelock fixes
>
> Basically the vanilla kernel each time pulls a random number of inodes
> from b_dirty, while the patched kernel tends to pull a fixed number of
> inodes (enqueue=1031) from b_dirty. The new behavior is very interesting...
This regularity is really strange. Did you have a chance to look more into
it? I find it highly unlikely that there would be exactly 1031 dirty inodes
in b_dirty list every time you call move_expired_inodes()...

Honza
--
Jan Kara <jack@xxxxxxx>
SUSE Labs, CR
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