linux-kernel - Re: [PATCH 2/3] perf: arm_cspmu: nvidia: update CNVLINK PMU events

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Message-ID: <20241023162636.GA29251@willie-the-truck>
Date: Wed, 23 Oct 2024 17:26:37 +0100
From: Will Deacon <will@...nel.org>
To: Besar Wicaksono <bwicaksono@...dia.com>
Cc: "suzuki.poulose@....com" <suzuki.poulose@....com>,
	"robin.murphy@....com" <robin.murphy@....com>,
	"catalin.marinas@....com" <catalin.marinas@....com>,
	"mark.rutland@....com" <mark.rutland@....com>,
	"linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
	Thierry Reding <treding@...dia.com>,
	Jon Hunter <jonathanh@...dia.com>, Vikram Sethi <vsethi@...dia.com>,
	Rich Wiley <rwiley@...dia.com>, Bob Knight <rknight@...dia.com>
Subject: Re: [PATCH 2/3] perf: arm_cspmu: nvidia: update CNVLINK PMU events

On Tue, Oct 15, 2024 at 05:21:06PM +0000, Besar Wicaksono wrote:
> 
> 
> > -----Original Message-----
> > From: Will Deacon <will@...nel.org>
> > Sent: Monday, October 14, 2024 8:19 AM
> > To: Besar Wicaksono <bwicaksono@...dia.com>
> > Cc: suzuki.poulose@....com; robin.murphy@....com;
> > catalin.marinas@....com; mark.rutland@....com; linux-arm-
> > kernel@...ts.infradead.org; linux-kernel@...r.kernel.org; linux-
> > tegra@...r.kernel.org; Thierry Reding <treding@...dia.com>; Jon Hunter
> > <jonathanh@...dia.com>; Vikram Sethi <vsethi@...dia.com>; Rich Wiley
> > <rwiley@...dia.com>; Bob Knight <rknight@...dia.com>
> > Subject: Re: [PATCH 2/3] perf: arm_cspmu: nvidia: update CNVLINK PMU
> > events
> > 
> > External email: Use caution opening links or attachments
> > 
> > 
> > On Wed, Sep 18, 2024 at 09:58:45PM +0000, Besar Wicaksono wrote:
> > > Rename loc* and rem* events in CNVLINK PMU to cmem* and gmem*
> > events.
> > >
> > > Signed-off-by: Besar Wicaksono <bwicaksono@...dia.com>
> > > ---
> > >  drivers/perf/arm_cspmu/nvidia_cspmu.c | 21 ++++++++++++++++++++-
> > >  1 file changed, 20 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/perf/arm_cspmu/nvidia_cspmu.c
> > b/drivers/perf/arm_cspmu/nvidia_cspmu.c
> > > index ea2d44adfa7c..d1cd9975e71a 100644
> > > --- a/drivers/perf/arm_cspmu/nvidia_cspmu.c
> > > +++ b/drivers/perf/arm_cspmu/nvidia_cspmu.c
> > > @@ -112,6 +112,25 @@ static struct attribute *mcf_pmu_event_attrs[] = {
> > >       NULL,
> > >  };
> > >
> > > +static struct attribute *mcf_cnvlink_pmu_event_attrs[] = {
> > > +     ARM_CSPMU_EVENT_ATTR(rd_bytes_cmem,                     0x0),
> > > +     ARM_CSPMU_EVENT_ATTR(rd_bytes_gmem,                     0x1),
> > > +     ARM_CSPMU_EVENT_ATTR(wr_bytes_cmem,                     0x2),
> > > +     ARM_CSPMU_EVENT_ATTR(wr_bytes_gmem,                     0x3),
> > > +     ARM_CSPMU_EVENT_ATTR(total_bytes_cmem,                  0x4),
> > > +     ARM_CSPMU_EVENT_ATTR(total_bytes_gmem,                  0x5),
> > > +     ARM_CSPMU_EVENT_ATTR(rd_req_cmem,                       0x6),
> > > +     ARM_CSPMU_EVENT_ATTR(rd_req_gmem,                       0x7),
> > > +     ARM_CSPMU_EVENT_ATTR(wr_req_cmem,                       0x8),
> > > +     ARM_CSPMU_EVENT_ATTR(wr_req_gmem,                       0x9),
> > > +     ARM_CSPMU_EVENT_ATTR(total_req_cmem,                    0xa),
> > > +     ARM_CSPMU_EVENT_ATTR(total_req_gmem,                    0xb),
> > > +     ARM_CSPMU_EVENT_ATTR(rd_cum_outs_cmem,                  0xc),
> > > +     ARM_CSPMU_EVENT_ATTR(rd_cum_outs_gmem,                  0xd),
> > > +     ARM_CSPMU_EVENT_ATTR(cycles,
> > ARM_CSPMU_EVT_CYCLES_DEFAULT),
> > > +     NULL,
> > > +};
> > > +
> > >  static struct attribute *generic_pmu_event_attrs[] = {
> > >       ARM_CSPMU_EVENT_ATTR(cycles,
> > ARM_CSPMU_EVT_CYCLES_DEFAULT),
> > >       NULL,
> > > @@ -234,7 +253,7 @@ static const struct nv_cspmu_match
> > nv_cspmu_match[] = {
> > >         .filter_default_val = NV_CNVL_FILTER_ID_MASK,
> > >         .name_pattern = "nvidia_cnvlink_pmu_%u",
> > >         .name_fmt = NAME_FMT_SOCKET,
> > > -       .event_attr = mcf_pmu_event_attrs,
> > > +       .event_attr = mcf_cnvlink_pmu_event_attrs,
> > >         .format_attr = cnvlink_pmu_format_attrs
> > >       },
> > 
> > Hmm. Isn't this a user-visible change? For example, will scripts driving
> > 'perf' with the old event names continue to work after this patch?
> > 
> 
> Yes this is user visible. I am expecting user script to be updated accordingly.
> Would this be reasonable?

I don't think so, no. We don't tend to require userspace changes as a
result of upgrading the kernel.

Will