linux-kernel - RE: [PATCH] Remove some PMU events for FUJITSU-MONAKA

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Message-ID:
 <OS3PR01MB6903726FDA70250F72A73410D4CB2@OS3PR01MB6903.jpnprd01.prod.outlook.com>
Date: Wed, 5 Mar 2025 06:40:28 +0000
From: "Yoshihiro Furudera (Fujitsu)" <fj5100bi@...itsu.com>
To: 'James Clark' <james.clark@...aro.org>
CC: 'John Garry' <john.g.garry@...cle.com>, 'Will Deacon' <will@...nel.org>,
	'Mike Leach' <mike.leach@...aro.org>, 'Leo Yan' <leo.yan@...ux.dev>, 'Peter
 Zijlstra' <peterz@...radead.org>, 'Ingo Molnar' <mingo@...hat.com>, 'Arnaldo
 Carvalho de Melo' <acme@...nel.org>, 'Namhyung Kim' <namhyung@...nel.org>,
	'Mark Rutland' <mark.rutland@....com>, 'Alexander Shishkin'
	<alexander.shishkin@...ux.intel.com>, 'Jiri Olsa' <jolsa@...nel.org>, 'Ian
 Rogers' <irogers@...gle.com>, 'Adrian Hunter' <adrian.hunter@...el.com>,
	"'Liang, Kan'" <kan.liang@...ux.intel.com>,
	"'linux-arm-kernel@...ts.infradead.org'"
	<linux-arm-kernel@...ts.infradead.org>, "'linux-perf-users@...r.kernel.org'"
	<linux-perf-users@...r.kernel.org>, "'linux-kernel@...r.kernel.org'"
	<linux-kernel@...r.kernel.org>, "Akio Kakuno (Fujitsu)"
	<fj3333bs@...itsu.com>
Subject: RE: [PATCH] Remove some PMU events for FUJITSU-MONAKA

Hi, James

> 
> Hi, James
> Thank you for your comment.
> 
> > On 27/02/2025 5:40 am, Yoshihiro Furudera wrote:
> > > The following events are not counted properly:
> > >
> > > 0x0037 LL_CACHE_MISS_RD
> > > 0x400B L3D_CACHE_LMISS_RD
> >
> > These two are discoverable so will still appear in
> > /sys/bus/event_source/devices/armv8_pmuv3_0/events/ if the hardware
> > says they exist. It might be better to change the json strings of
> > these two to warn that they don't work if that's the case, otherwise
> > Perf will still list them and you'll be worse off.
> 
> I will leave these 2 events and
> add a warning message to the description in the JSON file.
> I will handle other events in the same way as these 2 events.

I'm thinking of adding one of the following warnings
to the description of events where inaccurate counts 
occur on FUJITSU-MONAKA. 
Is this okay?

1.Simple version
"Note: This event does not count accurately."

2.Detailed version
"Note: This event does not count accurately because it counts as a miss regardless of whether the L3 prefetch is a hit or miss."

I think "2.Detailed version" is better.

example:
{
    "EventCode": "0x0396",
    "EventName": "L2D_CACHE_REFILL_L3D_MISS",
    "BriefDescription": "This event counts operations that cause a miss of the L3 cache. Note: This event does not count accurately because it counts as a miss regardless of whether the L3 prefetch is a hit or miss."
}

Best Regards,
Yoshihiro Furudera