RE: kupdated high load with heavy disk I/O

["Rechenberg, Andrew" <ARechenberg@shermanfinancialgroup.com>]

I have to find time to down the box because it's production, but as soon as
I do I'll post the numbers here.

Thanks for your help.	

Regards,
Andy.


> Could you please guys try to reproduce the problem with kernel profiling
> turned on and send us the output of readprofile? 

> This way we can know which function is using more CPU time, thus we can
> identify the problem. 


On Wed, 14 Nov 2001, John McCutchan wrote:

> Hi,
> 
> I also have the exact same behaviour when running mkisofs. During the 
> creation of the ISO the interactive feel is sluggish and after mkisofs
> is complete the box is sluggish and appears to lock up. During
> this sluggish period there is alot of disk activity. This is under
> 2.4.14
> 
> John
> On Wed, Nov 14, 2001 at 06:01:23PM -0500, Rechenberg, Andrew wrote:
> > Hello,
> > 
> > I have read some previous threads about kupdated consuming 99% of CPU
under
> > intense disk I/O in kernel 2.4.x on the archives of linux-kernel (April
> > 2001), and some issues about I/O problems on linux-mm, but have yet to
find
> > any suggestions or fixes.  I am currently experiencing the same issue
and
> > was wondering if anyone has any thoughts or suggestions on the issue.  I
am
> > not subscribed to the list so would you please CC: me directly on any
> > responses?  I can also check out the archives at theaimsgroup.com if a
CC:
> > would not be appropriate.  Thank you.
> > 
> > The issue that I am having is that when there is a heavy amount a disk
I/O,
> > the box becomes slightly unresponsive and kupdated is using 99.9% in
'top.'
> > Sometimes the box appears to totally lock up.  If one waits several
seconds
> > to a couple of minutes the system appears to 'unlock' and runs
sluggishly
> > for a while.  This cycle will repeat itself until the I/O subsides.  The
> > memory usage goes up to the full capacity of the box and then about 10MB
of
> > swap is used while this problem is occurring.  Memory and swap does not
get
> > relinquished afer the incident.
> > 
> > The issue appears in kernel 2.4.14 compiled directly from source from
> > kernel.org with no patches.  These problems manifest themselves with
only
> > one user doing heavy disk I/O.  The normal user load on the box can run
> > between 350-450 users so this behavior would be unacceptable because the
> > application that is being run is interactive.  With 450 users, and the
same
> > process running on a 2.2.20 kernel the performance of the box is great,
with
> > only a very slightly noticeable slow down.
> > 
> > I am running the Informix database UniVerse version 9.6.2.4 on a 4
processor
> > 700MHz Xeon Dell PowerEdge 6400.  The disk subsystem is controlled by a
PERC
> > 2/DC RAID card with 128MB on-board cache (megaraid driver compiled
directly
> > in to the kernel).  Data array is on 5 36GB 10K Ultra160 disks in a
RAID5
> > configuration.  The box has 4GB RAM, but is only using 2GB due to the
move
> > back to the 2.2 kernel.  The only kernel paramters that have been
modified
> > are in /proc/sys/kernel/sem.  All filesystems are ext2.
> > 
> > If you need any more detailed info, please let me know.  Any help on
this
> > problem would be immensely appreciated.  Thank you in advance.
> > 
> > Regards,
> > Andrew Rechenberg
> > Network Team, Sherman Financial Group
> > arechenberg@shermanfinancialgroup.com
> > 
> > --
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> > see: http://www.linux-mm.org/
> > 
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> 

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