lkml.org 
[lkml]   [2010]   [Nov]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: 2.6.36 io bring the system to its knees
On Mon, Nov 01, 2010 at 01:09:34AM +0000, Dimitrios Apostolou wrote:
> Hello,
>
> On Sun, 31 Oct 2010 09:51:32 +0800, Wu Fengguang wrote:
> > It may also help to lower the dirty ratio.
> >
> > echo 5 > /proc/sys/vm/dirty_ratio
> >
> > Memory pressure + heavy write can easily hurt responsiveness.
> >
> > - eats up to 20% (the default value for dirty_ratio) memory with dirty
> > pages and hence increase the memory pressure and number of swap IO
>
> My experience has been different with that. Wouldn't it make more sense
> to _increase_ dirty_ratio (to 50 lets say) and at the same time decrease
> dirty_background_ratio? That way writing to disk starts early, but the
> related apps stall waiting for I/O only when dirty_ratio is reached.

50% dirty ratio may help before the system goes thrashing (writing
processes will be throttled less/later). However Aidar is seeing hours
of unresponsiveness with heavy IO, in this case large dirty ratio
won't help reduce the throttling any more.

Thanks,
Fengguang


\
 
 \ /
  Last update: 2010-11-02 02:23    [W:0.082 / U:0.308 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site