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Date: Fri, 20 May 2016 22:25:52 -0700 From: Greg KH <gregkh@...uxfoundation.org> To: Ingo Molnar <mingo@...nel.org> Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>, stable@...r.kernel.org, jolsa@...hat.com, tglx@...utronix.de, torvalds@...ux-foundation.org, vincent.weaver@...ne.edu, bp@...en8.de, hpa@...or.com, eranian@...gle.com, markus.t.metzger@...el.com, acme@...hat.com, linux-kernel@...r.kernel.org, acme@...radead.org, peterz@...radead.org Subject: Re: [tip:perf/urgent] perf/x86/intel/pt: Generate PMI in the STOP region as well On Tue, May 17, 2016 at 10:40:34AM +0200, Ingo Molnar wrote: > > * Alexander Shishkin <alexander.shishkin@...ux.intel.com> wrote: > > > tip-bot for Alexander Shishkin <tipbot@...or.com> writes: > > > > > Commit-ID: ab92b232ae05c382c3df0e3d6a5c6d16b639ac8c > > > Gitweb: http://git.kernel.org/tip/ab92b232ae05c382c3df0e3d6a5c6d16b639ac8c > > > Author: Alexander Shishkin <alexander.shishkin@...ux.intel.com> > > > AuthorDate: Tue, 10 May 2016 16:18:32 +0300 > > > Committer: Ingo Molnar <mingo@...nel.org> > > > CommitDate: Thu, 12 May 2016 14:45:59 +0200 > > > > > > perf/x86/intel/pt: Generate PMI in the STOP region as well > > > > > > Currently, the PT driver always sets the PMI bit one region (page) before > > > the STOP region so that we can wake up the consumer before we run out of > > > room in the buffer and have to disable the event. However, we also need > > > an interrupt in the last output region, so that we actually get to disable > > > the event (if no more room from new data is available at that point), > > > otherwise hardware just quietly refuses to start, but the event is > > > scheduled in and we end up losing trace data till the event gets removed. > > > > > > For a cpu-wide event it is even worse since there may not be any > > > re-scheduling at all and no chance for the ring buffer code to notice > > > that its buffer is filled up and the event needs to be disabled (so that > > > the consumer can re-enable it when it finishes reading the data out). In > > > other words, all the trace data will be lost after the buffer gets filled > > > up. > > > > > > This patch makes PT also generate a PMI when the last output region is > > > full. > > > > > > Reported-by: Markus Metzger <markus.t.metzger@...el.com> > > > Signed-off-by: Alexander Shishkin <alexander.shishkin@...ux.intel.com> > > > Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org> > > > Cc: <stable@...r.kernel.org> > > > > Can we also have this one queued up for stable 4.4 and 4.5? > > Agreed. > > Acked-by: Ingo Molnar <mingo@...nel.org> The filename moved around, now fixed and queued up, thanks. greg k-h
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