Very Computer

by **Jeff Busc** » Fri, 24 Aug 2001 07:00:10

machine: Compaq Proliant DL360 w/4GB mem, dual 36GB SCSI drives
OS: RedHat 7.1 + errata updates, kernel-enterprise-2.4.7-2.i686.rpm from
'Roswell 2'

Under heavy I/O (Apache and a custom C++ module which do lots of mmap and
munmap calls over large data sets - 7GB total), the machine slows to a
crawl. The problem persists even after live traffic to the machine ceases.
A top listing shows both cpu's at 100% system. Any commands (ps, uname,
whatever) take minutes to return results.

The same setup on RH 6.2 with 2.4.3-ac3 works fine. Please let me know what
information may be useful to debugging this problem (no oops yet), and other
kernels to try; I'm looking at 2.4.8-ac9 right now.

Thanks,
Jeff Busch
System Administrator
Half.com - an eBay company

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by **Jeff Busc** » Fri, 24 Aug 2001 10:20:08

Quote:> I have been trying to duplicate a similar problem in my lab that happened
> to me on a production box with 2.4.5. do you have a test that will allow
> you to replicate the problem at will?

This problem only occured under live traffic on a production box. Our
normal sanity checks worked fine, but they only generate light traffic. The
running code and the data are proprietary, so I can't hand 'em out. I'll
see if we can come up with a generic case that replicates the problem.

-Jeff

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by **Francois Romie** » Fri, 24 Aug 2001 19:30:12

Quote:> > The same setup on RH 6.2 with 2.4.3-ac3 works fine. Please let me know what
> > information may be useful to debugging this problem (no oops yet), and other
> > kernels to try; I'm looking at 2.4.8-ac9 right now.

> I'd be interested to know how 2.4.8-ac9 fares. It has the saner parts of
> the VM work from the Linus tree and other stuff from Rik, Marcelo and co.

I have added the data of 2.4.8-ac7 build for 2.4.8-ac{8,9} at
http://www.cogenit.fr/linux/bench/. The graphs are under 2.4.8-acXX/img.
The successive runs on a same session are now bounded on the graphs.
The occasionaly high levels of irq and cs on ac9 says nothing good about
interactivity.

--
Ueimor
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Very Computer

RH 2.4.7-2 kernel slows to a crawl under heavy i/o

RH 2.4.7-2 kernel slows to a crawl under heavy i/o

RH 2.4.7-2 kernel slows to a crawl under heavy i/o

RH 2.4.7-2 kernel slows to a crawl under heavy i/o