lkml.org 
[lkml]   [2003]   [Aug]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: High CPU load with kswapd and heavy disk I/O
Hi!

Ken Savage wrote:
> Short version:
> ----------------
> kernels 2.4.17 --> 2.4.21
> Dual Athlon SMP system
> 4GB RAM, 2GB swap
> 3ware RAID, filled with millions of files across thousands of directories.
> reiserfs 3.6
>
> The following command is guaranteed to lock out the box by activating
> kswapd to >95% CPU, blocking out pings, everything.
>
> find /RAID/data/ -type f -mtime +180 | xargs rm
>

Can you send before, during and after:
cat /proc/meminfo
cat /proc/slabinfo

And maybe:
vmstat 1

Real kernel hackers (not me...) will find that information very usefull ;)

Regards,
Nuno Silva


> Details:
> ----------
> Applying the rmap patch seems to prevent kswapd from hogging the CPU,
> but causes it to freeze up for some other reason. (The server is remote,
> so I can't view the console.) Likewise 2.6.0-test* causes freezeups.
> Mind you, the server is under a fair bit of CPU and disk load -- hundreds
> of processes/threads all actively running. I suspect something in rmap
> has made its way into 2.6 and our usage pattern is triggering the same
> fault in both places.
>
> It appears as though the system is unable to efficiently clean up disk
> buffer memory when called on to do so. In the Documentation/, there
> is mention of a buffermem sysctl, but that's nowhere to be found.
> It's obviously been removed/replaced... Is there any way to limit the
> amount of buffer memory used by the system, that way if/when kswapd
> needs to reclaim it, there's very little work for it to do?
>
> Admittedly, that's just masking the problem, as opposed to solving it.
> Any idea why kswapd is having such a tough go?? Known solutions
> for this problem?
>
> TIA,
>
> Ken
>
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/
>

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:47    [W:0.059 / U:5.108 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site