From: Namhyung Kim <namhyung@kernel.org>
To: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: peterz@infradead.org, mingo@redhat.com, acme@kernel.org,
eranian@google.com, mark.rutland@arm.com,
alexander.shishkin@linux.intel.com, jolsa@kernel.org,
irogers@google.com, adrian.hunter@intel.com,
kan.liang@linux.intel.com, tglx@linutronix.de, bp@alien8.de,
dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com,
linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
santosh.shukla@amd.com, ananth.narayan@amd.com,
sandipan.das@amd.com
Subject: Re: [PATCH 5/8] perf/amd/ibs: Don't allow freq mode event creation through ->config interface
Date: Tue, 8 Oct 2024 23:27:26 -0700 [thread overview]
Message-ID: <ZwYiTvrcVkF4W7O3@google.com> (raw)
In-Reply-To: <79ccf66b-6bf0-4cc8-b001-aae44f09dde9@amd.com>
On Tue, Oct 08, 2024 at 11:00:37AM +0530, Ravi Bangoria wrote:
> >> Don't allow freq mode event creation through perf_event_attr->config
> >> interface.
> >
> > Sounds reasonable. I agree the freq mode should use the standard
> > interface using attr->sample_freq. But I'm not sure if the behaivor is
> > defined when attr->freq is set and attr->sample_freq is 0. Maybe this
> > should be handled in the generic code.
>
> I also could not find any reason to allow {freq=1, sample_freq=0}, but:
>
> 1) perf_event_open() allows it.
> 2) ioctl(PERF_EVENT_IOC_PERIOD) allows it.
> 3) all generic code explicitly checks for ->sample_freq != 0 wherever
> ->freq == 1.
>
> I will prepare and post a patch to reject such event and see if there
> are any objections.
Hmm.. now I think that the kernel won't treat it as a sampling event and
would ignore the attr.freq value. Setting IOC_PERIOD to 0 would disable
sampling then. Sorry for the noise.
Thanks,
Namhyung
next prev parent reply other threads:[~2024-10-09 6:27 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-07 3:48 [PATCH 0/8] perf/amd/ibs: Fix sample period computations Ravi Bangoria
2024-10-07 3:48 ` [PATCH 1/8] perf/amd/ibs: Remove IBS_{FETCH|OP}_CONFIG_MASK macros Ravi Bangoria
2024-10-07 3:48 ` [PATCH 2/8] perf/amd/ibs: Remove pointless sample period check Ravi Bangoria
2024-10-07 19:16 ` Namhyung Kim
2024-10-07 3:48 ` [PATCH 3/8] perf/amd/ibs: Fix ->config to sample period calculation for OP pmu Ravi Bangoria
2024-10-07 3:48 ` [PATCH 4/8] perf/amd/ibs: Fix perf_ibs_op.cnt_mask for CurCnt Ravi Bangoria
2024-10-07 3:48 ` [PATCH 5/8] perf/amd/ibs: Don't allow freq mode event creation through ->config interface Ravi Bangoria
2024-10-07 19:24 ` Namhyung Kim
2024-10-08 5:30 ` Ravi Bangoria
2024-10-09 6:27 ` Namhyung Kim [this message]
2024-10-07 3:48 ` [PATCH 6/8] perf/amd/ibs: Add pmu specific minimum period Ravi Bangoria
2024-10-07 19:30 ` Namhyung Kim
2024-10-08 5:46 ` Ravi Bangoria
2024-10-09 6:32 ` Namhyung Kim
2024-10-07 3:48 ` [PATCH 7/8] perf/amd/ibs: Add ->check_period() callback Ravi Bangoria
2024-10-07 19:33 ` Namhyung Kim
2024-10-07 3:48 ` [PATCH 8/8] perf/core: Introduce pmu->adjust_period() callback Ravi Bangoria
2024-10-09 6:33 ` [PATCH 0/8] perf/amd/ibs: Fix sample period computations Namhyung Kim
2024-11-19 13:35 ` Ravi Bangoria
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