From: Leo Yan <leo.yan@arm.com>
To: Adrian Hunter <adrian.hunter@intel.com>
Cc: James Clark <james.clark@linaro.org>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Mike Leach <mike.leach@linaro.org>,
John Garry <john.g.garry@oracle.com>,
Will Deacon <will@kernel.org>, Leo Yan <leo.yan@linux.dev>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Namhyung Kim <namhyung@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@kernel.org>, Ian Rogers <irogers@google.com>,
Thomas Falcon <thomas.falcon@intel.com>,
coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org,
linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 1/2] perf cs-etm: Fix decoding for sparse CPU maps
Date: Mon, 19 Jan 2026 13:59:07 +0000 [thread overview]
Message-ID: <20260119135907.GA2732125@e132581.arm.com> (raw)
In-Reply-To: <c50da3af-e6f5-4b40-bd25-1e37fd6bf0d5@intel.com>
On Mon, Jan 19, 2026 at 02:11:43PM +0200, Adrian Hunter wrote:
[...]
> >> 0 0 0x200 [0x90]: PERF_RECORD_ID_INDEX nr: 4
> >> ... id: 771 idx: 0 cpu: 2 tid: -1
> >> ... id: 772 idx: 1 cpu: 3 tid: -1
> >> ... id: 773 idx: 0 cpu: 2 tid: -1
> >> ... id: 774 idx: 1 cpu: 3 tid: -1
> >
> > Seems to me that this patch works around the issue by using the CPU ID
> > instead, but event->auxtrace.idx is broken.
> >
> > Should we store the correct index in event->auxtrace.idx (e.g., in the
> > __perf_event__synthesize_id_index()) ?
>
> The idx value represents a perf events ring buffer. Events on the same
> CPU can share the same ring buffer. But in the case of per-thread
> recording, different threads have different ring buffers and therefore
> different idx values.
>
> So I don't think the idx value is wrong. It is just not the same thing
> as CPU number.
Thanks a lot for the explanation, this makes sense to me.
Leo
next prev parent reply other threads:[~2026-01-19 13:59 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-19 10:18 [PATCH v2 0/2] perf cs-etm: Fix decoding for sparse CPU maps James Clark
2026-01-19 10:18 ` [PATCH v2 1/2] " James Clark
2026-01-19 11:15 ` Leo Yan
2026-01-19 11:55 ` James Clark
2026-01-19 14:53 ` Leo Yan
2026-01-19 15:16 ` James Clark
2026-01-19 15:43 ` Leo Yan
2026-01-20 10:44 ` Leo Yan
2026-01-19 12:11 ` Adrian Hunter
2026-01-19 13:59 ` Leo Yan [this message]
2026-01-19 10:18 ` [PATCH v2 2/2] perf cs-etm: Test " James Clark
2026-01-20 11:22 ` Leo Yan
2026-01-20 20:42 ` Arnaldo Carvalho de Melo
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20260119135907.GA2732125@e132581.arm.com \
--to=leo.yan@arm.com \
--cc=acme@kernel.org \
--cc=adrian.hunter@intel.com \
--cc=alexander.shishkin@linux.intel.com \
--cc=coresight@lists.linaro.org \
--cc=irogers@google.com \
--cc=james.clark@linaro.org \
--cc=john.g.garry@oracle.com \
--cc=jolsa@kernel.org \
--cc=leo.yan@linux.dev \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-perf-users@vger.kernel.org \
--cc=mark.rutland@arm.com \
--cc=mike.leach@linaro.org \
--cc=mingo@redhat.com \
--cc=namhyung@kernel.org \
--cc=peterz@infradead.org \
--cc=suzuki.poulose@arm.com \
--cc=thomas.falcon@intel.com \
--cc=will@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox