From: Namhyung Kim <namhyung@gmail.com>
To: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
Paul Mackerras <paulus@samba.org>, Ingo Molnar <mingo@elte.hu>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/5] perf top: Use active evsel for non-sample events on old kernel
Date: Tue, 31 Jan 2012 09:31:13 +0900 [thread overview]
Message-ID: <4F273651.2020908@gmail.com> (raw)
In-Reply-To: <20120130185532.GC15935@infradead.org>
2012-01-31 3:55 AM, Arnaldo Carvalho de Melo wrote:
> Em Sun, Jan 29, 2012 at 05:55:52PM +0900, Namhyung Kim escreveu:
>> If multiple events are specified on old kernel,
>> perf_evlist__id2evsel() returns NULL for non-sampling events
>> since the sample.id doesn't contain valid value, and it triggers
>> assert below. If only one event is given, the function returns
>> the evsel regardless of sample.id, this is why most case cause
>> no problem on old kernel.
>>
>> Fix it by using active evsel.
>
> How about this one instead:
>
> diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
> index a6d50e3..3ffb320 100644
> --- a/tools/perf/util/evlist.c
> +++ b/tools/perf/util/evlist.c
> @@ -349,6 +349,10 @@ struct perf_evsel *perf_evlist__id2evsel(struct perf_evlist *evlist, u64 id)
> hlist_for_each_entry(sid, pos, head, node)
> if (sid->id == id)
> return sid->evsel;
> +
> + if (!perf_evlist__sample_id_all(evlist))
> + return list_entry(evlist->entries.next, struct perf_evsel, node);
> +
> return NULL;
> }
>
> That way we won't have to patch other tools that would get the same
> problem in such new tool/old kernel combos, right?
>
Right, looks good to me.
> Do you see any problem with not checking the header type?
>
No, I don't, at least for now :)
> Also please try to avoid using perf_session fields, prefer to use
> perf_{evlist,evsel} when possible, in this case you could use
> perf_evlist__sample_id_all(evlist), for instance.
>
> - Arnaldo
>
OK, will do that later.
Thanks,
Namhyung
next prev parent reply other threads:[~2012-01-31 0:31 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-29 8:55 [PATCH 1/5] perf top: Use active evsel for non-sample events on old kernel Namhyung Kim
2012-01-29 8:55 ` [PATCH 2/5] perf record: Add error message for EMFILE Namhyung Kim
2012-01-29 15:28 ` David Ahern
2012-01-30 1:09 ` Namhyung Kim
[not found] ` <CAKYOsXxxmG8xQfPcn9xW+Dzd_-Qo8jUv8071UHdC18RBatq=uw@mail.gmail.com>
2012-01-30 18:56 ` Arnaldo Carvalho de Melo
2012-01-29 8:55 ` [PATCH 3/5] perf stat: " Namhyung Kim
2012-01-29 8:55 ` [PATCH 4/5] perf tools: Remove unnecessary ctype.h inclusion Namhyung Kim
2012-01-31 13:22 ` [tip:perf/core] " tip-bot for Namhyung Kim
2012-01-29 8:55 ` [PATCH 5/5] perf lock: Document lock info subcommand Namhyung Kim
2012-01-31 13:21 ` [tip:perf/core] " tip-bot for Namhyung Kim
2012-01-30 18:55 ` [PATCH 1/5] perf top: Use active evsel for non-sample events on old kernel Arnaldo Carvalho de Melo
2012-01-31 0:31 ` Namhyung Kim [this message]
2012-01-31 0:34 ` Arnaldo Carvalho de Melo
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