Re: bad command responsiveness Proliant DL 585

[Mike Galbraith <efault@gmx.de>]

On Wed, 2006-06-14 at 09:59 +0200, David Osojnik wrote:
> Hello,
> 
> We have a problem with four HP Proliant DL 585 servers with 4 AMD
> Opteron processors and 16Gb of memory and 3x 300Gb U320 SCSI disks and
> with all the latest firmware. we noticed bad command responsiveness in
> an production environment and poor performance (web server and mysql)
> The problem is good reproducible if creating a large file 30Gb in size with:
> 
> time dd if=/dev/zero of=test.file bs=3072 count=10240000
> 
> on the root partition no matter which one reiserfs, ext3
> 
> what happens is I open three more console windows and do random commands
> like: "ls, w, route -n, ifconfig" but the commands freezes for random
> time (this time is from 1 minute to 15minutes!! per command execution
> time) when the command starts working (after 5minutes) i try it again
> and the command freezes again for a random time... the strange thing is
> that if one command freezes all other commands freeze too when one
> starts to work others work too. (if running top it stops refreshing for
> the lockup period)

Does top freeze if started from an mlockall(MCL_PRESENT|MCL_FUTURE)
shell running at realtime priority?

Try SysRq-T and SysRq-M during freezes to gather info about VM and task
state during freeze.

	-Mike