looking for help, attempting to debug high latency in 2.4 kernel
cfriesen at nortelnetworks.com
Sat Dec 4 08:58:36 EST 2004
I'm running 2.4.22 on ppc32. Embedded system, just 74xx cpu, dual tulip network
links and fiberchannel card. Card has 1.5GB of memory, rootfs is tmpfs, system
has some NFS mounts.
We're seeing userspace delayed for almost a second every so often. No idea
what's causing it.
We've got scheduler instrumentation showing a usespace task starting to run,
then a bunch of tasks being put on the runqueue, and finally we wake up and
start running normally again almost a full second later. The timing is not
exactly the same in each case, but it's usually close to a second of delay.
I'm looking for some tips on how to go about tracking this down.
Where are my delays likely to be coming from? Long-running code paths? Long
periods with interrupts off? I dunno where to start.
Would porting lockmeter be a good idea? Is there anyone who's already done this
I appreciate any help.
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