Re: High load average on disk I/O on 2.6.17-rc3

[Jason Schoonover]

Hi Robert,

There are, this is the relevant output of the process list:

 ...
 4659 pts/6    Ss     0:00 -bash
 4671 pts/5    R+     0:12 cp -a test-dir/ new-test
 4676 ?        D      0:00 [pdflush]
 4679 ?        D      0:00 [pdflush]
 4687 pts/4    D+     0:01 hdparm -t /dev/sda
 4688 ?        D      0:00 [pdflush]
 4690 ?        D      0:00 [pdflush]
 4692 ?        D      0:00 [pdflush]
 ...

This was when I was copying a directory and then doing a performance test with 
hdparm in a separate shell.  The hdparm process was in [D+] state and 
basically waited until the cp was finished.  During the whole thing there 
were up to 5 pdflush processes in [D] state.

The 5 minute load average hit 8.90 during this test.

Does that help?

Jason

-------Original Message-----
From: Robert Hancock
Sent: Friday 05 May 2006 16:12
To: linux-kernel
Subject: Re: High load average on disk I/O on 2.6.17-rc3

Jason Schoonover wrote:
> Hi all,
>
> I'm not sure if this is the right list to post to, so please direct me to
> the appropriate list if this is the wrong one.
>
> I'm having some problems on the latest 2.6.17-rc3 kernel and SCSI disk I/O.
> Whenever I copy any large file (over 500GB) the load average starts to
> slowly rise and after about a minute it is up to 7.5 and keeps on rising
> (depending on how long the file takes to copy).  When I watch top, the
> processes at the top of the list are cp, pdflush, kjournald and kswapd.

Are there some processes stuck in D state? These will contribute to the
load average even if they are not using CPU.
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