Messages in this thread | | | Subject | Re: [PATCH] smp: generic ipi_raise tracepoint | From | Wojciech Kudla <> | Date | Thu, 21 May 2020 21:11:36 +0100 |
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On 21/05/2020 20:00, Nadav Amit wrote:
>> - if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu))) >> + if (llist_add(&csd->llist, &per_cpu(call_single_queue, cpu))) { >> + if (trace_ipi_raise_enabled()) > > Why do you need this check? trace_ipi_raise() will do the same check before > actual tracing: > > if (static_key_false(&__tracepoint_##name.key) >
Yes, my motivation for conditional logic was performance-driven. Thanks for pointing out the implicit check.
> > In general, I think there are too many trace-points. They look benign(i.e., > free), but can cause worse code to be generated as they behave as a memory > clobber. Many times the same result can be achieved with a probe. >
Thank you for the review, I agree this may not be optimal. Let's just stop here. There's a different patch I submitted today that follows Peter's suggestions about smp function calls being much more sensible target for new tracepoints.
http://lkml.kernel.org/r/e6141d56-1da1-6c00-198f-cbe4385327ff@gmail.com
Thanks, W.
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