Is it possible for ksoftirqd to have hold of some resource that other
processes may need to obtain in the mprotect() syscall?
The background for this is as follows:
I've done some work with modifying the linux scheduler to support
additional scheduling classes with limits on cpu percentages available
for each class under stress.
We're hitting a strange scenario under the following conditions:
sched class A is given 90% of the cpu and is based on strict static
priority scheduling
process x is put in sched class A with and is event driven
process y is put in sched class A with a lower priority than x and is a
cpu hog
We would expect to see a background of y running, interrupted by x when
it becomes runnable.
We seem to be seeing a case where process x calls mprotect() and then
blocks while process y runs for large amounts of time. Eventually we
see ksoftirqd run and immediately after that process x wakes up and runs
for a while, but by this time its too late and some timers have expired.
Hence the question--is it possible for ksoftirqd to have hold of some
resource that process x tries to obtain in the mprotect() syscall?
Thanks,
Chris
--
Chris Friesen | MailStop: 043/33/F10
Nortel Networks | work: (613) 765-0557
3500 Carling Avenue | fax: (613) 765-2986
Nepean, ON K2H 8E9 Canada | email: [email protected]