Messages in this thread | | | From | "Zhang, Rui" <> | Subject | RE: [PATCH 2/3] perf/x86/rapl: Fix energy counter detection | Date | Sun, 17 Jan 2021 14:44:04 +0000 |
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> -----Original Message----- > From: Peter Zijlstra <peterz@infradead.org> > Sent: Saturday, January 16, 2021 8:48 PM > To: Zhang, Rui <rui.zhang@intel.com> > Cc: mingo@redhat.com; acme@kernel.org; mark.rutland@arm.com; > alexander.shishkin@linux.intel.com; jolsa@redhat.com; > namhyung@kernel.org; linux-kernel@vger.kernel.org; x86@kernel.org; > kan.liang@linux.intel.com; ak@linux.intel.com > Subject: Re: [PATCH 2/3] perf/x86/rapl: Fix energy counter detection > Importance: High > > On Sat, Jan 16, 2021 at 08:19:35AM +0000, Zhang, Rui wrote: > > > > > > > -----Original Message----- > > > From: Peter Zijlstra <peterz@infradead.org> > > > Sent: Saturday, January 16, 2021 4:03 AM > > > To: Zhang, Rui <rui.zhang@intel.com> > > > Cc: mingo@redhat.com; acme@kernel.org; mark.rutland@arm.com; > > > alexander.shishkin@linux.intel.com; jolsa@redhat.com; > > > namhyung@kernel.org; linux-kernel@vger.kernel.org; x86@kernel.org; > > > kan.liang@linux.intel.com; ak@linux.intel.com > > > Subject: Re: [PATCH 2/3] perf/x86/rapl: Fix energy counter detection > > > Importance: High > > > > > > On Fri, Jan 15, 2021 at 05:22:07PM +0800, Zhang Rui wrote: > > > > In the RAPL ENERGY_COUNTER MSR, only the lower 32bits represent > > > > the energy counter, and the higher 32bits are reserved. > > > > > > > > Add the MSR mask for these MSRs to fix a problem that the RAPL PMU > > > > events are added erroneously when higher 32bits contain non-zero > value. > > > > > > Why would these high bits be non-zero? > > > > On SPR platform, the high bits of Psys energy counter are reused for other > purpose. > > High bits for other RAPL domains energy counters still return 0. > > > > I didn't mention this because I thought this patch should be okay as a > generic fix. > > But it doesn't fix anything.. there's not anything broken, except on that daft > SPR thing.
Well, yes. Before SPR, this is just a potential issue. But things on SPR suggests that this potential issue may become a real one. So are you suggesting me to also include the SPR information as the justification of this patch?
Thanks, rui
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