lkml.org 
[lkml]   [2008]   [Sep]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [PATCH] dm-snapshot: poor copy-on-write performance due to I/O reordering
Date
Kazuo Ito <ito.kazuo@oss.ntt.co.jp> wrote:

> Write throughput to LVM snapshot origin volume is an order
> of magnitude slower than those to LV without snapshots or
> snapshot target volumes, especially in the case of sequential
> writes with O_SYNC on.
>
> The following patch originally written by Kevin Jamieson and
> Jan Blunck and slightly modified for the current RCs by myself
> tries to improve the performance by modifying the behaviour
> of kcopyd, so that it pushes back an I/O job to the head of
> the job queue instead of the tail as process_jobs() currently
> does when it has to wait for free pages. This way, write
> requests aren't shuffled to cause extra seeks.

Did you check for starvation problems, too?



\
 
 \ /
  Last update: 2008-09-17 17:41    [W:0.072 / U:0.388 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site