[lttng-dev] [RFC PATCH] sched: Fix sched_wakeup tracepoint

Steven Rostedt rostedt at goodmis.org
Wed Jun 17 14:47:09 EDT 2015

On Wed, 17 Jun 2015 11:23:00 -0700
Cong Wang <xiyou.wangcong at gmail.com> wrote:

> On Tue, Jun 9, 2015 at 2:13 AM, Peter Zijlstra <peterz at infradead.org> wrote:
> >
> > So how about we introduce the 'waking' tracepoint and leave the existing
> > wakeup one in place and preserve its woken semantics.
> >
> > Steven, can we do aliases? Where one tracepoint is known to userspace
> > under multiple names? In that case we could rename the thing to woken
> > and have an alias wakeup which we can phase out over time.
> >
> > The patch also takes away the success parameter to the tracepoint, but
> > does not quite go as far as actually removing it from the tracepoint
> > itself.
> >
> > We can do that in a follow up patch which we can quickly revert if it
> > turns out people are actually still using that for something.
> +1 to this patch. How is it going?

It's not a top priority. But it shouldn't be too hard to implement.
This could be something I do after the 4.2 merge window closes.

-- Steve

> Here at Twitter, we are analyzing scheduling latencies too, with our
> own tool using existing tracepoints, it would be nice to have more
> granularity on the scheduling latency.
> And, you probably want to change perf sched to respect this
> new 'waking' event too. ;)
> Thanks.

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