From: Yang Shi <shy828301@gmail.com>
To: James Clark <james.clark@arm.com>
Cc: Leo Yan <leo.yan@linaro.org>,
linux-perf-users@vger.kernel.org,
LAK <linux-arm-kernel@lists.infradead.org>,
coresight@lists.linaro.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
mathieu.poirier@linaro.org, adrian.hunter@intel.com,
Jiri Olsa <jolsa@kernel.org>,
acme@redhat.com, mike.leach@linaro.org,
Will Deacon <will@kernel.org>,
suzuki.poulose@arm.com, yang@os.amperecomputing.com
Subject: Re: [BUG] perf: No samples found when using kcore + coresight
Date: Wed, 29 Mar 2023 16:25:24 -0700 [thread overview]
Message-ID: <CAHbLzkoFkxpLuaW93nPrxxvtuHiRmObOnZfRY9YPXcGumzv33A@mail.gmail.com> (raw)
In-Reply-To: <64db6d95-8aca-48cc-80e1-e68211922071@arm.com>
On Wed, Mar 29, 2023 at 9:08 AM James Clark <james.clark@arm.com> wrote:
>
>
>
> On 14/03/2023 00:36, Leo Yan wrote:
> > On Mon, Mar 13, 2023 at 11:15:44AM -0700, Yang Shi wrote:
> >
> > [...]
> >
> >>> Just a quick summary, here we have two issues:
> >>>
> >>> - With command:
> >>> perf record -e cs_etm/@tmc_etf63/k --kcore --per-thread \
> >>> -- taskset --cpu-list 1 uname",
> >>>
> >>> perf doesn't enable "text poke" attribution.
> >>
> >> No, it enables "text poke" and perf fails to decode coresight trace
> >> data too. It doesn't matter whether "--kcore" is after or before "-e
> >> cs/etm/@tmc_etf63/k".
> >
> > Understand now. Thanks for correction, if so we can ignore this one.
> >
> > Leo
>
> To me it looks like it's only --per-thread and --kcore together that
> cause the issue. I can't see if that was mentioned previously in this
> thread.
If "--pre-thread" is not passed in, perf record failed with "failed to
mmap with 12 (Cannot allocate memory)". Sorry for not mentioning this
in the first place. I was quite focused on --kcore and didn't realize
they may be related.
>
> If it is --per-thread that's causing the issue then I think I have an
> idea why it might be. There are some assumptions and different paths
> taken in decoding in that mode that aren't correct. It causes some other
> issues to do with ordering and timestamps as well and I wanted to fix it
> previously. I wouldn't say that the text-poke change has caused a
> regression, as decoding in this mode was always a bit buggy.
>
> Maybe this is another reason to fix it properly.
next prev parent reply other threads:[~2023-03-29 23:25 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CAHbLzkrJQTrYBtPkf=jf3OpQ-yBcJe7XkvQstX9j2frz4WF-SQ@mail.gmail.com>
2023-03-07 10:32 ` [BUG] perf: No samples found when using kcore + coresight James Clark
2023-03-07 19:45 ` Yang Shi
2023-03-08 19:56 ` Yang Shi
2023-03-09 11:38 ` Leo Yan
[not found] ` <CAHbLzkpvLHnyL5J5kB_ke3CWVq2=MOEdEQsGex56+Esfgqh1=g@mail.gmail.com>
2023-03-13 12:14 ` Leo Yan
2023-03-13 18:15 ` Yang Shi
2023-03-14 0:36 ` Leo Yan
2023-03-28 0:53 ` Yang Shi
2023-03-28 8:59 ` James Clark
2023-03-28 16:16 ` Yang Shi
2023-03-29 16:08 ` James Clark
2023-03-29 23:25 ` Yang Shi [this message]
2023-03-30 8:17 ` James Clark
2023-03-29 16:11 ` James Clark
2023-03-30 10:36 ` James Clark
2023-03-30 19:54 ` Yang Shi
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