Messages in this thread | | | Date | Fri, 27 Nov 2009 11:02:13 +0800 | Subject | Re: PATCH: softlockup: Fix hung_task_check_count sysctl | From | Américo Wang <> |
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On Fri, Nov 27, 2009 at 10:55 AM, Frederic Weisbecker <fweisbec@gmail.com> wrote: > On Fri, Nov 27, 2009 at 10:46:53AM +0800, Américo Wang wrote: >> On Fri, Nov 27, 2009 at 10:28 AM, Anton Blanchard <anton@samba.org> wrote: >> > >> > I'm seeing spikes of up to 0.5ms in khungtaskd on a large machine. To reduce >> > this source of jitter I tried setting hung_task_check_count to 0: >> > >> > # echo 0 > /proc/sys/kernel/hung_task_check_count >> > >> > which didn't have the intended response. Change to a post increment of >> > max_count, so a value of 0 means check 0 tasks. >> > >> > Signed-off-by: Anton Blanchard <anton@samba.org> >> >> >> Ack. >> >> I would also suggest to make 'max_count' as unsigned long, >> since sysctl_hung_task_check_count is. >> >> Thanks. > > > Also, the batch_count thing should be dropped I think. > This is a hardcoded, not overridable pause after 1024 > threads checks to avoid latencies caused by rcu_read_lock. > But now we have PREEMPT_RCU so people can enable it if > they care about latency. We should remove it as it adds > unnecessary complexity.
This sounds OK for me.
> > I'm preparing a patch for that, on top of Anton patch. >
Great!
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