linux-kernel - Re: [PATCH 01/20] perf/x86/intel: Add PMU support for Clearwater Forest

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Message-ID: <20250206075356.GF7145@noisy.programming.kicks-ass.net>
Date: Thu, 6 Feb 2025 08:53:56 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: "Mi, Dapeng" <dapeng1.mi@...ux.intel.com>
Cc: Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>, Ian Rogers <irogers@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Kan Liang <kan.liang@...ux.intel.com>,
	Andi Kleen <ak@...ux.intel.com>,
	Eranian Stephane <eranian@...gle.com>, linux-kernel@...r.kernel.org,
	linux-perf-users@...r.kernel.org, Dapeng Mi <dapeng1.mi@...el.com>
Subject: Re: [PATCH 01/20] perf/x86/intel: Add PMU support for Clearwater
 Forest

On Thu, Feb 06, 2025 at 09:31:46AM +0800, Mi, Dapeng wrote:
> 
> On 1/28/2025 12:26 AM, Peter Zijlstra wrote:
> > On Thu, Jan 23, 2025 at 02:07:02PM +0000, Dapeng Mi wrote:
> >> From PMU's perspective, Clearwater Forest is similar to the previous
> >> generation Sierra Forest.
> >>
> >> The key differences are the ARCH PEBS feature and the new added 3 fixed
> >> counters for topdown L1 metrics events.
> >>
> >> The ARCH PEBS is supported in the following patches. This patch provides
> >> support for basic perfmon features and 3 new added fixed counters.
> >>
> >> Signed-off-by: Dapeng Mi <dapeng1.mi@...ux.intel.com>
> >> ---
> >>  arch/x86/events/intel/core.c | 24 ++++++++++++++++++++++++
> >>  1 file changed, 24 insertions(+)
> >>
> >> diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
> >> index b140c1473a9d..5e8521a54474 100644
> >> --- a/arch/x86/events/intel/core.c
> >> +++ b/arch/x86/events/intel/core.c
> >> @@ -2220,6 +2220,18 @@ static struct extra_reg intel_cmt_extra_regs[] __read_mostly = {
> >>  	EVENT_EXTRA_END
> >>  };
> >>  
> >> +EVENT_ATTR_STR(topdown-fe-bound,       td_fe_bound_skt,        "event=0x9c,umask=0x01");
> >> +EVENT_ATTR_STR(topdown-retiring,       td_retiring_skt,        "event=0xc2,umask=0x02");
> >> +EVENT_ATTR_STR(topdown-be-bound,       td_be_bound_skt,        "event=0xa4,umask=0x02");
> >> +
> >> +static struct attribute *skt_events_attrs[] = {
> >> +	EVENT_PTR(td_fe_bound_skt),
> >> +	EVENT_PTR(td_retiring_skt),
> >> +	EVENT_PTR(td_bad_spec_cmt),
> >> +	EVENT_PTR(td_be_bound_skt),
> >> +	NULL,
> >> +};
> > The skt here is skymont, which is what Sierra Forest was based on, and
> > you just said that these counters are new with Darkmont, and as such the
> > lot should be called: dmt or whatever the proper trigraph is.
> 
> Sorry for late response since the Chinese new year holiday.
> 
> Sierra Forest is based on Crestmont instead of Skymont. 

I hate all these names :-( But yeah, you're right.

> The 3 new fixed counters are introduced from Skymont and Darkmont
> inherits them. So these attributes are named with "skt" suffix.

Fair enough.

But how come this is new for darkmont and wasn't done for
arrowlake/lunarlake which have skymont based e-cores?