Messages in this thread Patch in this message |  | | | Subject | Re: [patch] fix uml slowness caused by ptrace preemption bug on host | | From | Miklos Szeredi <> | | Date | Fri, 20 Mar 2009 09:27:10 +0100 |
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On Fri, 20 Mar 2009, Peter Zijlstra wrote: > On Thu, 2009-03-19 at 23:23 +0100, Miklos Szeredi wrote: > > > > This patch solves this by not scheduling on preempt_enable() after > > ptrace_stop() has woken up the tracer. > > Nice,.. however did you find this?
Ftrace helped a lot, it's a really cool tool :). I had to patch it with this, otherwise the timestamps would be totally off:
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index bd38c5c..557c2dd 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -108,7 +108,7 @@ u64 ring_buffer_time_stamp(int cpu) preempt_disable_notrace(); /* shift to debug/test normalization and TIME_EXTENTS */ - time = sched_clock() << DEBUG_SHIFT; + time = cpu_clock(cpu) << DEBUG_SHIFT; preempt_enable_no_resched_notrace(); return time;
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