Re: [PATCH 3/8] writeback: switch to per-bdi threads for flushingdata
From: Daniel Walker
Date: Tue Sep 08 2009 - 09:46:47 EST
On Tue, 2009年09月08日 at 11:23 +0200, Jens Axboe wrote:
>
This gets rid of pdflush for bdi writeout and kupdated style cleaning.
>
pdflush writeout suffers from lack of locality and also requires more
>
threads to handle the same workload, since it has to work in a
>
non-blocking fashion against each queue. This also introduces lumpy
>
behaviour and potential request starvation, since pdflush can be starved
>
for queue access if others are accessing it. A sample ffsb workload that
>
does random writes to files is about 8% faster here on a simple SATA drive
>
during the benchmark phase. File layout also seems a LOT more smooth in
>
vmstat:
This patch has a checkpatch error, and couple of warnings.. Here's one
of the warnings which I though was concerning..
WARNING: trailing semicolon indicates no statements, indent implies
otherwise
#388: FILE: fs/fs-writeback.c:177:
+ } else if (wb->task);
+ wake_up_process(wb->task);
I suppose that could be a defect .. btw, patch 7 of 8 also has a few
trivial warnings.
Daniel
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