From: Leo Yan <leo.yan@linaro.org>
To: Al Grant <Al.Grant@arm.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>,
John Garry <john.garry@huawei.com>, Will Deacon <will@kernel.org>,
Mathieu Poirier <mathieu.poirier@linaro.org>,
James Clark <James.Clark@arm.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Mark Rutland <Mark.Rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
Adrian Hunter <adrian.hunter@intel.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 0/7] perf arm-spe: Enable timestamp
Date: Wed, 7 Apr 2021 21:15:29 +0800 [thread overview]
Message-ID: <20210407131529.GA585163@leoy-ThinkPad-X240s> (raw)
In-Reply-To: <AM6PR08MB335124DC0080EA95A817D71786769@AM6PR08MB3351.eurprd08.prod.outlook.com>
Hi Al,
On Tue, Apr 06, 2021 at 09:38:32AM +0000, Al Grant wrote:
[...]
> > This patch set is to enable timestamp for Arm SPE trace. It reads out TSC
> > parameters from mmap page and stores into auxtrace info structure;
>
> Why not synthesize a PERF_RECORD_TIME_CONV - isn't that specifically to
> capture the TSC parameters from the mmap page? If a generic mechanism
> exists it would be better to use it, otherwise we'll have to do this again for
> future trace formats.
Good point! Actually "perf record" tool has synthesized event
PERF_RECORD_TIME_CONV. This patch series is studying the
implementation from Intel-PT, so the question is why the existed
implementations (like Intel-PT, Intel-BTS) don't directly use
PERF_RECORD_TIME_CONV for retriving TSC parameters.
I agree using PERF_RECORD_TIME_CONV for TSC parameter is better than
extending auxtrace info. Will experiment for this.
> perf_read_tsc_conversion and perf_event__synth_time_conv are currently
> in arch/x86/util/tsc.c, but nothing in them is x86-specific and they could be
> moved somewhere more generic.
This is not true on the mainline kernel; these functions have been
moved into the file util/tsc.c.
Thanks for suggestions,
Leo
next prev parent reply other threads:[~2021-04-07 13:15 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-03 7:23 [PATCH v2 0/7] perf arm-spe: Enable timestamp Leo Yan
2021-04-03 7:23 ` [PATCH v2 1/7] perf arm-spe: Remove unused enum value ARM_SPE_PER_CPU_MMAPS Leo Yan
2021-04-03 7:23 ` [PATCH v2 2/7] perf arm-spe: Store TSC parameters in auxtrace info Leo Yan
2021-04-03 7:23 ` [PATCH v2 3/7] perf arm-spe: Dump TSC parameters Leo Yan
2021-04-03 7:23 ` [PATCH v2 4/7] perf arm-spe: Convert event kernel time to counter value Leo Yan
2021-04-03 7:23 ` [PATCH v2 5/7] perf arm-spe: Assign kernel time to synthesized event Leo Yan
2021-04-03 7:23 ` [PATCH v2 6/7] perf arm-spe: Bail out if the trace is later than perf event Leo Yan
2021-04-03 7:23 ` [PATCH v2 7/7] perf arm-spe: Don't wait for PERF_RECORD_EXIT event Leo Yan
2021-04-06 9:38 ` [PATCH v2 0/7] perf arm-spe: Enable timestamp Al Grant
2021-04-07 13:15 ` Leo Yan [this message]
2021-04-07 13:28 ` Adrian Hunter
2021-04-07 13:40 ` Leo Yan
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