Messages in this thread | | | Subject | Re: [PATCH][GIT PULL] tracing: Fix compile issue for trace_sched_wakeup.c | From | Steven Rostedt <> | Date | Thu, 21 Oct 2010 07:01:02 -0400 |
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On Thu, 2010-10-21 at 09:22 +0200, Peter Zijlstra wrote: > On Thu, 2010-10-21 at 11:58 +0900, Masami Hiramatsu wrote: > > > It seems there can be a bug in stop_machine() routine under > > heavy use. usually that is called just once at a time, but jump > > label and optprobe might call it heavily (thousands times?). > > So some racy situation can be happen easily. > > There are people doing hotplug stress testing, that too results in heavy > stop_machine usage.
But with hotplug, isn't there a bit more time between stop machine calls? That is, you need to do a bit of work to bring down or up a CPU, and that will slow down the number of stop machine calls together.
Here, we do a simple change and call stop machine() several times.
Although, I agree, I do not think the bug is in stop machine itself, but perhaps the way we are using it might have some niche anomaly that we are hitting.
-- Steve
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