From: Jiri Olsa <jolsa@redhat.com>
To: Andi Kleen <andi@firstfloor.org>
Cc: acme@kernel.org, jolsa@kernel.org, linux-kernel@vger.kernel.org,
Andi Kleen <ak@linux.intel.com>
Subject: Re: [PATCH v1 04/15] perf, tools: Support weak groups
Date: Wed, 2 Aug 2017 09:35:07 +0200 [thread overview]
Message-ID: <20170802073507.GA13890@krava> (raw)
In-Reply-To: <20170724234015.5165-5-andi@firstfloor.org>
On Mon, Jul 24, 2017 at 04:40:04PM -0700, Andi Kleen wrote:
> From: Andi Kleen <ak@linux.intel.com>
>
> Setting up groups can be complicated due to the
> complicated scheduling restrictions of different PMUs.
> User tools usually don't understand all these restrictions.
> Still in many cases it is useful to set up groups and
> they work most of the time. However if the group
> is set up wrong some members will not reported any values
> because they never get scheduled.
>
> Add a concept of a 'weak group': try to set up a group,
> but if it's not schedulable fallback to not using
> a group. That gives us the best of both worlds:
> groups if they work, but still a usable fallback if they don't.
>
> In theory it would be possible to have more complex fallback
> strategies (e.g. try to split the group in half), but
> the simple fallback of not using a group seems to work for now.
>
> So far the weak group is only implemented for perf stat,
> not for record.
>
> Here's an unschedulable group (on IvyBridge with SMT on)
>
> % perf stat -e '{branches,branch-misses,l1d.replacement,l2_lines_in.all,l2_rqsts.all_code_rd}' -a sleep 1
>
> 73,806,067 branches
> 4,848,144 branch-misses # 6.57% of all branches
> 14,754,458 l1d.replacement
> 24,905,558 l2_lines_in.all
> <not supported> l2_rqsts.all_code_rd <------- will never report anything
>
> With the weak group:
>
> % perf stat -e '{branches,branch-misses,l1d.replacement,l2_lines_in.all,l2_rqsts.all_code_rd}:W' -a sleep 1
>
> 125,366,055 branches (80.02%)
> 9,208,402 branch-misses # 7.35% of all branches (80.01%)
> 24,560,249 l1d.replacement (80.00%)
> 43,174,971 l2_lines_in.all (80.05%)
> 31,891,457 l2_rqsts.all_code_rd (79.92%)
looks handy, few comments below
thanks,
jirka
>
> The extra event scheduled with some extra multiplexing
>
> Signed-off-by: Andi Kleen <ak@linux.intel.com>
> ---
SNIP
> diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
> index 97d6b6c42014..551ed938e05c 100644
> --- a/tools/perf/builtin-stat.c
> +++ b/tools/perf/builtin-stat.c
> @@ -564,7 +564,7 @@ static int __run_perf_stat(int argc, const char **argv)
> int interval = stat_config.interval;
> char msg[BUFSIZ];
> unsigned long long t0, t1;
> - struct perf_evsel *counter;
> + struct perf_evsel *counter, *c2, *leader;
> struct timespec ts;
> size_t l;
> int status = 0;
> @@ -595,6 +595,32 @@ static int __run_perf_stat(int argc, const char **argv)
> evlist__for_each_entry(evsel_list, counter) {
> try_again:
> if (create_perf_stat_counter(counter) < 0) {
> + /* Weak group failed. Reset the group. */
> + if (errno == EINVAL &&
> + counter->leader != counter &&
> + counter->weak_group) {
could you please put this de-grouping code into a function?
> + bool is_open = true;
> +
> + pr_debug("Weak group for %s/%d failed\n",
> + counter->leader->name, counter->nr_members);
> + leader = counter->leader;
> + evlist__for_each_entry(evsel_list, c2) {
we have for_each_group_member
> + if (c2 == counter)
> + is_open = false;
> + if (c2->leader == leader) {
> + if (is_open)
> + perf_evsel__close(c2,
> + c2->cpus ? c2->cpus->nr :
> + cpu_map__nr(evsel_list->cpus),
> + thread_map__nr(evsel_list->threads));
> + c2->leader = c2;
> + c2->nr_members = 0;
> + }
> + }
> + counter = leader;
> + goto try_again;
> + }
> +
> /*
> * PPC returns ENXIO for HW counters until 2.6.37
> * (behavior changed with commit b0a873e).
SNIP
next prev parent reply other threads:[~2017-08-02 7:35 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-24 23:40 Support standalone metrics and metric groups for perf Andi Kleen
2017-07-24 23:40 ` [PATCH v1 01/15] perf, tools, stat: Fix buffer overflow while freeing events Andi Kleen
2017-08-01 8:11 ` Jiri Olsa
2017-07-24 23:40 ` [PATCH v1 02/15] perf, tools: Tighten detection of BPF events Andi Kleen
2017-08-02 7:35 ` Jiri Olsa
2017-08-02 19:10 ` Arnaldo Carvalho de Melo
2017-07-24 23:40 ` [PATCH v1 03/15] perf, tools, stat: Fix saved values rbtree lookup Andi Kleen
2017-08-02 7:35 ` Jiri Olsa
2017-08-02 19:11 ` Arnaldo Carvalho de Melo
2017-08-14 17:43 ` [tip:perf/core] perf " tip-bot for Andi Kleen
2017-07-24 23:40 ` [PATCH v1 04/15] perf, tools: Support weak groups Andi Kleen
2017-08-02 7:35 ` Jiri Olsa [this message]
2017-07-24 23:40 ` [PATCH v1 05/15] perf, tools: Add missing newline to expr parser error messages Andi Kleen
2017-08-02 7:37 ` Jiri Olsa
2017-08-14 17:44 ` [tip:perf/core] perf " tip-bot for Andi Kleen
2017-07-24 23:40 ` [PATCH v1 06/15] perf, tools: Add utility function to detect SMT status Andi Kleen
2017-07-24 23:40 ` [PATCH v1 07/15] perf, tools: Expression parser enhancements for metrics Andi Kleen
2017-08-07 9:51 ` Jiri Olsa
2017-07-24 23:40 ` [PATCH v1 08/15] perf, tools: Increase maximum number of events in expressions Andi Kleen
2017-07-24 23:40 ` [PATCH v1 09/15] perf, tools: Dedup events in expression parsing Andi Kleen
2017-08-07 9:51 ` Jiri Olsa
2017-07-24 23:40 ` [PATCH v1 10/15] perf, tools: Support metric_group and no event name in json parser Andi Kleen
2017-07-24 23:40 ` [PATCH v1 11/15] perf, tools, stat: Factor out generic metric printing Andi Kleen
2017-07-24 23:40 ` [PATCH v1 12/15] perf, tools, stat: Support JSON metrics in perf stat Andi Kleen
2017-07-24 23:40 ` [PATCH v1 13/15] perf, tools, list: Add metric groups to perf list Andi Kleen
2017-07-24 23:40 ` [PATCH v1 14/15] perf, tools, stat: Don't use ctx for saved values lookup Andi Kleen
2017-07-24 23:40 ` [PATCH v1 15/15] perf, tools: Support duration_time Andi Kleen
2017-08-07 10:36 ` Jiri Olsa
2017-07-26 14:15 ` Support standalone metrics and metric groups for perf Jiri Olsa
2017-07-26 15:38 ` Andi Kleen
2017-07-28 8:48 ` Jiri Olsa
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