From: Andi Kleen <andi@firstfloor.org>
To: Stephane Eranian <eranian@google.com>
Cc: Andi Kleen <andi@firstfloor.org>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Jiri Olsa <jolsa@kernel.org>, Ingo Molnar <mingo@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Namhyung Kim <namhyung@kernel.org>,
Andi Kleen <ak@linux.intel.com>
Subject: Re: [PATCH 05/10] perf, tools, stat: Basic support for TopDown in perf stat
Date: Wed, 16 Dec 2015 22:21:04 +0100 [thread overview]
Message-ID: <20151216212104.GZ15533@two.firstfloor.org> (raw)
In-Reply-To: <CABPqkBQ-e8DZvZ6y_QPsf2ggqJ4CcaM_EaFwMPyy80ASY=Hsgw@mail.gmail.com>
> > +/*
> > + * Check whether we can use a group for top down.
> > + * Without a group may get bad results due to multiplexing.
> > + */
>
> That is not because you have a counter used by the NMI that
> you cannot group. If HT is off you have plenty of counters to
> do this.
Such a heuristic wouldn't work on Atom where there are no more
counters in this case.
> > +static bool check_group(bool *warn)
> > +{
> > + int n;
> > +
> > + if (sysctl__read_int("kernel/nmi_watchdog", &n) < 0)
> > + return false;
> > + if (n > 0) {
> > + *warn = true;
> > + return false;
> > + }
> > + return true;
> > +}
> > +
>
> I do not like this part very much. You are pulling in x86 specific
> knowledge into
> builtin_stat.c. Why not move this into an x86 specific file?
Done.
> > err = parse_events(evsel_list, transaction_attrs, NULL);
> > @@ -1511,6 +1579,36 @@ static int add_default_attributes(void)
> > return 0;
> > }
> >
> > + if (topdown_run) {
> > + char *str = NULL;
> > + bool warn = false;
> > +
> > + filter_events(topdown_attrs, &str, check_group(&warn));
> > + if (topdown_attrs[0] && str) {
> > + if (warn)
> > + fprintf(stderr,
> > + "nmi_watchdog enabled with topdown. May give wrong results.\n"
> > + "Disable with echo 0 > /proc/sys/kernel/nmi_watchdog\n");
>
> This is x86 specific. Why not just try it out and in case of error
> suggest checking
> if pinned system-wide events exist (such as NMI watchdog on x86). that would
> be more generic.
That's really complicated, i would have to tear down all state and then
resubmit all the events. I think just checking the NMI watchdog is good
enough. I couldn't give a sensible error message for the generic case
anyways.
-Andi
--
ak@linux.intel.com -- Speaking for myself only.
next prev parent reply other threads:[~2015-12-16 21:21 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-16 0:54 Add top down metrics to perf stat v2 Andi Kleen
2015-12-16 0:54 ` [PATCH 01/10] perf, tools: Dont stop PMU parsing on alias parse error Andi Kleen
2015-12-21 16:08 ` Jiri Olsa
2015-12-16 0:54 ` [PATCH 02/10] perf, tools, stat: Force --per-core mode for .agg-per-core aliases Andi Kleen
2015-12-16 14:16 ` Stephane Eranian
2015-12-21 16:14 ` Jiri Olsa
2015-12-21 16:16 ` Jiri Olsa
2015-12-16 0:54 ` [PATCH 03/10] perf, tools, stat: Avoid fractional digits for integer scales Andi Kleen
2015-12-16 14:22 ` Stephane Eranian
2015-12-16 0:54 ` [PATCH 04/10] perf, tools, stat: Scale values by unit before metrics Andi Kleen
2015-12-16 0:54 ` [PATCH 05/10] perf, tools, stat: Basic support for TopDown in perf stat Andi Kleen
2015-12-16 14:32 ` Stephane Eranian
2015-12-16 21:21 ` Andi Kleen [this message]
2015-12-17 9:26 ` Stephane Eranian
2015-12-17 14:03 ` Andi Kleen
2015-12-16 0:54 ` [PATCH 06/10] perf, tools, stat: Add computation of TopDown formulas Andi Kleen
2015-12-16 0:54 ` [PATCH 07/10] perf, tools, stat: Add extra output of counter values with -v Andi Kleen
2015-12-16 0:54 ` [PATCH 08/10] x86, perf: Support sysfs files depending on SMT status Andi Kleen
2015-12-16 8:53 ` Peter Zijlstra
2015-12-16 12:48 ` Stephane Eranian
2015-12-16 16:26 ` Andi Kleen
2015-12-16 0:54 ` [PATCH 09/10] x86, perf: Add Top Down events to Intel Core Andi Kleen
2015-12-16 0:54 ` [PATCH 10/10] x86, perf: Add Top Down events to Intel Atom Andi Kleen
2015-12-17 10:27 ` Add top down metrics to perf stat v2 Stephane Eranian
2015-12-17 14:01 ` Andi Kleen
2015-12-17 23:31 ` Stephane Eranian
2015-12-18 1:55 ` Andi Kleen
2015-12-18 9:31 ` Stephane Eranian
2015-12-18 21:38 ` Andi Kleen
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=20151216212104.GZ15533@two.firstfloor.org \
--to=andi@firstfloor.org \
--cc=acme@kernel.org \
--cc=ak@linux.intel.com \
--cc=eranian@google.com \
--cc=jolsa@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=namhyung@kernel.org \
--cc=peterz@infradead.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;
as well as URLs for NNTP newsgroup(s).