From: Will Deacon <will@kernel.org>
To: Rob Herring <robh@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Jiri Olsa <jolsa@redhat.com>, Mark Rutland <mark.rutland@arm.com>,
Ian Rogers <irogers@google.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>,
Zachary.Leaf@arm.com, Raphael Gault <raphael.gault@arm.com>,
Jonathan Cameron <Jonathan.Cameron@huawei.com>,
Namhyung Kim <namhyung@kernel.org>,
Itaru Kitayama <itaru.kitayama@gmail.com>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v6 02/10] arm64: perf: Enable PMU counter direct access for perf event
Date: Wed, 31 Mar 2021 16:38:46 +0100 [thread overview]
Message-ID: <20210331153845.GB7815@willie-the-truck> (raw)
In-Reply-To: <CAL_JsqKqKKb8uXSxQKT4ZMqMv8dt3ABpP+T8x+A1-zb2RKjCNA@mail.gmail.com>
On Tue, Mar 30, 2021 at 04:08:11PM -0500, Rob Herring wrote:
> On Tue, Mar 30, 2021 at 12:09 PM Rob Herring <robh@kernel.org> wrote:
> > On Tue, Mar 30, 2021 at 10:31 AM Will Deacon <will@kernel.org> wrote:
> > > The logic here feels like it
> > > could with a bit of untangling.
> >
> > Yes, I don't love it, but couldn't come up with anything better. It is
> > complicated by the fact that flags have to be set before we assign the
> > counter and can't set/change them when we assign the counter. It would
> > take a lot of refactoring with armpmu code to fix that.
>
> How's this instead?:
>
> if (armv8pmu_event_want_user_access(event) || !armv8pmu_event_is_64bit(event))
> event->hw.flags |= ARMPMU_EL0_RD_CNTR;
>
> /*
> * At this point, the counter is not assigned. If a 64-bit counter is
> * requested, we must make sure the h/w has 64-bit counters if we set
> * the event size to 64-bit because chaining is not supported with
> * userspace access. This may still fail later on if the CPU cycle
> * counter is in use.
> */
> if (armv8pmu_event_is_64bit(event) &&
> (!armv8pmu_event_want_user_access(event) ||
> armv8pmu_has_long_event(cpu_pmu) || (hw_event_id ==
> ARMV8_PMUV3_PERFCTR_CPU_CYCLES)))
> event->hw.flags |= ARMPMU_EVT_64BIT;
I thought there were some cases where we could assign cycles event to an
event counter; does that not happen anymore?
Will
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next prev parent reply other threads:[~2021-03-31 15:40 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-11 0:08 [PATCH v6 00/10] libperf and arm64 userspace counter access support Rob Herring
2021-03-11 0:08 ` [PATCH v6 01/10] arm64: pmu: Add function implementation to update event index in userpage Rob Herring
2021-03-30 15:30 ` Will Deacon
2021-03-11 0:08 ` [PATCH v6 02/10] arm64: perf: Enable PMU counter direct access for perf event Rob Herring
2021-03-30 11:30 ` Zachary Leaf
2021-03-30 15:31 ` Will Deacon
2021-03-30 17:09 ` Rob Herring
2021-03-30 21:08 ` Rob Herring
2021-03-31 15:38 ` Will Deacon [this message]
2021-03-31 17:52 ` Rob Herring
2021-04-01 9:04 ` Will Deacon
2021-03-31 16:00 ` Will Deacon
2021-04-01 19:45 ` Rob Herring
2021-04-07 12:44 ` Will Deacon
2021-04-08 11:08 ` Mark Rutland
2021-04-08 18:38 ` Rob Herring
2021-04-19 16:14 ` Will Deacon
2021-04-19 19:00 ` Rob Herring
2021-03-11 0:08 ` [PATCH v6 03/10] tools/include: Add an initial math64.h Rob Herring
2021-03-11 0:08 ` [PATCH v6 04/10] libperf: Add evsel mmap support Rob Herring
2021-03-12 13:58 ` Jiri Olsa
2021-03-12 14:34 ` Rob Herring
2021-03-12 18:29 ` Jiri Olsa
2021-03-31 22:06 ` Rob Herring
2021-03-11 0:08 ` [PATCH v6 05/10] libperf: tests: Add support for verbose printing Rob Herring
2021-03-11 0:08 ` [PATCH v6 06/10] libperf: Add support for user space counter access Rob Herring
2021-05-04 21:40 ` Ian Rogers
2021-05-05 2:12 ` Rob Herring
2021-03-11 0:08 ` [PATCH v6 07/10] libperf: Add arm64 support to perf_mmap__read_self() Rob Herring
2021-03-11 0:08 ` [PATCH v6 08/10] perf: arm64: Add test for userspace counter access on heterogeneous systems Rob Herring
2021-03-15 16:09 ` Masayoshi Mizuma
2021-03-11 0:08 ` [PATCH v6 09/10] perf: arm64: Add tests for 32-bit and 64-bit counter size userspace access Rob Herring
2021-03-11 0:08 ` [PATCH v6 10/10] Documentation: arm64: Document PMU counters access from userspace Rob Herring
2021-03-31 16:00 ` Will Deacon
2021-03-30 11:31 ` [PATCH v6 00/10] libperf and arm64 userspace counter access support Zachary Leaf
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