RE: High CPU usage (up to server hang) under heavy I/O load

["Sylvain COUTANT" <sylvain.coutant@illicom.com>]

Hi Marcello,

> You want to try this

The server now runs 2.4.26 with the patch applied for about two hours. I
have triggered backups so that it is a little bit stressed.

My first feeling is something changed. Once the whole physical memory has
been in use by the kernel, I saw some load problems rising (as before), but
the server did not hang (as before ;-) and system load has gone down
smoothly (took about one or two minutes).

Now it looks stable under medium I/O load. I'll give it more stress next
night and I'll report the behaviour here.

However, kswapd is still a major CPU eater : 5 minutes of CPU time consumed
since the reboot (2 hours). kupdated is at 1 minute and bdflush is 12
seconds. /proc/sys/vm are boot time standard settings with no change. Actual
system load is near 4 for 15 minutes average, which I consider very bad
result regarding currently running application. I believe I should be near 1
...


Do you think I could achieve better results (smoother operations) by
tweaking those /proc/sys/vm settings ?


Regards,
Sylvain.