linux-kernel - RE: [PATCH v2 0/6] perf arm64 metricgroup support

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Date:   Mon, 29 Mar 2021 16:07:17 -0500
From:   "Paul A. Clarke" <pc@...ibm.com>
To:     John Garry <john.garry@...wei.com>
Cc:     will@...nel.org, mathieu.poirier@...aro.org, leo.yan@...aro.org,
        peterz@...radead.org, mingo@...hat.com, acme@...nel.org,
        mark.rutland@....com, alexander.shishkin@...ux.intel.com,
        jolsa@...hat.com, namhyung@...nel.org, irogers@...gle.com,
        linuxarm@...wei.com, kjain@...ux.ibm.com,
        kan.liang@...ux.intel.com, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, zhangshaokun@...ilicon.com
Subject: RE: [PATCH v2 0/6] perf arm64 metricgroup support

On Fri, Mar 26, 2021 at 10:57:40AM +0000, John Garry wrote:
> On 25/03/2021 20:39, Paul A. Clarke wrote:
> > On Thu, Mar 25, 2021 at 06:33:12PM +0800, John Garry wrote:
> > > Metric reuse support is added for pmu-events parse metric testcase.
> > > This had been broken on power9 recentlty:
> > > https://lore.kernel.org/lkml/20210324015418.GC8931@li-24c3614c-2adc-11b2-a85c-85f334518bdb.ibm.com/
> > 
> > Much better.  Before:
> > --
> > $ perf test -v 10 2>&1 | grep -i error | wc -l
> > 112
> > --
> > After:
> > --
> > $ perf test -v 10 2>&1 | grep -i error | wc -l
> > 17
> > --
> > 
> > And these seem like different types of issues:
> > --
> > $ perf test -v 10 2>&1 | grep -i error
> > Error string 'Cannot find PMU `nest_mcs01_imc'. Missing kernel support?' help '(null)'
> > Error string 'Cannot find PMU `nest_mcs01_imc'. Missing kernel support?' help '(null)'
> > Error string 'Cannot find PMU `nest_mcs23_imc'. Missing kernel support?' help '(null)'
> > Error string 'Cannot find PMU `nest_mcs23_imc'. Missing kernel support?' help '(null)'
> > Error string 'Cannot find PMU `nest_mcs01_imc'. Missing kernel support?' help '(null)'
> > Error string 'Cannot find PMU `nest_mcs01_imc'. Missing kernel support?' help '(null)'
> > Error string 'Cannot find PMU `nest_mcs23_imc'. Missing kernel support?' help '(null)'
> > Error string 'Cannot find PMU `nest_mcs23_imc'. Missing kernel support?' help '(null)'
> > Error string 'Cannot find PMU `nest_powerbus0_imc'. Missing kernel support?' help '(null)'
> > Error string 'Cannot find PMU `nest_mcs23_imc'. Missing kernel support?' help '(null)'
> > Error string 'Cannot find PMU `nest_mcs01_imc'. Missing kernel support?' help '(null)'
> > Error string 'Cannot find PMU `nest_mcs01_imc'. Missing kernel support?' help '(null)'
> > Error string 'Cannot find PMU `nest_mcs01_imc'. Missing kernel support?' help '(null)'
> > Error string 'Cannot find PMU `nest_mcs01_imc'. Missing kernel support?' help '(null)'
> > Error string 'Cannot find PMU `nest_mcs23_imc'. Missing kernel support?' help '(null)'
> > Error string 'Cannot find PMU `nest_mcs23_imc'. Missing kernel support?' help '(null)'
> > Error string 'Cannot find PMU `nest_mcs23_imc'. Missing kernel support?' help '(null)'
> > --
> > 
> 
> This looks suspicious.
> 
> Firstly, does /sys/bus/event_source/devices/nest_mcs01_imc (or others,
> above) exist on your system? I guess not.
> 
> Secondly, checking Documentation/powerpc/imc.rst, we have examples of:
> nest_mcs01/PM_MCS01_64B_R...
> 
> So is the PMU name correct in the metric file for nest_mcs01_imc? Looking at
> the kernel driver file, arch/powerpc/perf/imc-pmu.c, it seems to be correct.
> Not sure.

I ran with a newer kernel, and the above errors disappeared, replaced with
about 10 of:
--
Error string 'Cannot find PMU `hv_24x7'. Missing kernel support?' help '(null)'
--

...but I was running without a hypervisor, so I tried the same kernel on a
PowerVM-virtualized system and the "hv_24x7" messages went away, but the
"nest" messages returned.  This may all be expected behavior... I confess
I haven't followed these new perf capabilities closely.

It's extremely likely that none of these errors has anything to do with your
changes. :-)

PC