From: Jiri Olsa <jolsa@redhat.com>
To: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>, Jiri Olsa <jolsa@kernel.org>,
lkml <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@kernel.org>,
Namhyung Kim <namhyung@kernel.org>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Jonas Rabenstein <jonas.rabenstein@studium.uni-erlangen.de>,
Nageswara R Sastry <nasastry@in.ibm.com>,
Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Subject: Re: [PATCH] perf tools: Move precise_ip detection into perf_evsel__open
Date: Sat, 23 Mar 2019 16:04:22 +0100 [thread overview]
Message-ID: <20190323150422.GA22122@krava> (raw)
In-Reply-To: <20190315145225.GC5200@krava>
On Fri, Mar 15, 2019 at 03:52:25PM +0100, Jiri Olsa wrote:
> On Fri, Mar 15, 2019 at 11:35:04AM -0300, Arnaldo Carvalho de Melo wrote:
>
> SNIP
>
> > > +static void display_attr(struct perf_event_attr *attr)
> > > +{
> > > + if (verbose >= 2) {
> > > + fprintf(stderr, "%.60s\n", graph_dotted_line);
> > > + fprintf(stderr, "perf_event_attr:\n");
> > > + perf_event_attr__fprintf(stderr, attr, __open_attr__fprintf, NULL);
> > > + fprintf(stderr, "%.60s\n", graph_dotted_line);
> > > + }
> > > +}
> > > +
> > > +static int perf_event_open(struct perf_evsel *evsel,
> > > + pid_t pid, int cpu, int group_fd,
> > > + unsigned long flags)
> >
> >
> > The patch is ok, but I think the naming of this function is too generic,
> > so I'm renaming it to:
> >
> > static int perf_evsel__open_adjust_precise_ip(struct perf_evsel *evsel,
> > pid_t pid, int cpu, int group_fd,
> > unsigned long flags)
> >
> > Ok?
>
> ok
>
> >
> > The perf_evsel__open() code is already complex with that fallback
> > mechanism, this is just one more way of fallbacking when asking the
> > kernel for something that may fail.
> >
> > In fact what happens if the precise_ip that is being asked _is_
> > supported but sys_perf_event_open() fails because some other
> > perf_event_attr attribute that is set is not supported?
>
> it's outside the scope of standard feature fallback code,
> so we will try it for any possible fallback variant, so:
>
> we will try all possible precise_ip (3,2,1,0) and they will
> all fail because of the unsupported attribute - so we will
> restore the precise_ip back and continue in standard fallback
> code that will eventualy switch that attribute off
>
> >
> > I see, it gets it back restored to what the user asked so that the
> > standard fallback is tried, ok, I'll apply with just the rename for this
> > function,
>
> thanks,
> jirka
ping, there's rebased version in my perf/fixes branch
jirka
next prev parent reply other threads:[~2019-03-23 15:04 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-05 15:25 [PATCH 0/8] perf tools: Assorted fixes Jiri Olsa
2019-03-05 15:25 ` [PATCH 1/8] perf c2c: Fix c2c report for empty numa node Jiri Olsa
2019-03-09 20:05 ` [tip:perf/urgent] " tip-bot for Jiri Olsa
2019-03-05 15:25 ` [PATCH 2/8] perf tools: Add error path into hist_entry__init Jiri Olsa
2019-03-09 20:06 ` [tip:perf/urgent] perf hist: " tip-bot for Jiri Olsa
2019-03-05 15:25 ` [PATCH 3/8] perf hist: Fix memory leak of srcline Jiri Olsa
2019-03-09 20:07 ` [tip:perf/urgent] " tip-bot for Jiri Olsa
2019-03-05 15:25 ` [PATCH 4/8] perf tools: Read and store caps/max_precise in perf_pmu Jiri Olsa
2019-03-09 20:07 ` [tip:perf/urgent] " tip-bot for Jiri Olsa
2019-03-05 15:25 ` [PATCH 5/8] perf tools: Get precise_ip from the pmu config Jiri Olsa
2019-03-05 16:13 ` Andi Kleen
2019-03-05 16:28 ` Jiri Olsa
2019-03-05 16:40 ` Andi Kleen
2019-03-07 15:35 ` [PATCHv2 " Jiri Olsa
2019-03-07 16:51 ` Andi Kleen
2019-03-07 22:32 ` Jiri Olsa
2019-03-14 14:01 ` Jiri Olsa
2019-03-14 15:49 ` Andi Kleen
2019-03-15 12:15 ` [PATCH] perf tools: Move precise_ip detection into perf_evsel__open Jiri Olsa
2019-03-15 14:05 ` Andi Kleen
2019-03-15 14:35 ` Arnaldo Carvalho de Melo
2019-03-15 14:52 ` Jiri Olsa
2019-03-23 15:04 ` Jiri Olsa [this message]
2019-03-25 14:53 ` Arnaldo Carvalho de Melo
2019-03-05 15:25 ` [PATCH 6/8] perf tools: Probe for precise_ip with simple attr Jiri Olsa
2019-03-09 20:08 ` [tip:perf/urgent] perf evsel: " tip-bot for Jiri Olsa
2019-03-05 15:25 ` [PATCH 7/8] perf tools: Fix double free in perf_data__close Jiri Olsa
2019-03-09 20:09 ` [tip:perf/urgent] perf session: " tip-bot for Jiri Olsa
2019-03-05 15:25 ` [PATCH 8/8] perf tools: Force perf_data__open|close zero data->file.path Jiri Olsa
2019-03-09 20:09 ` [tip:perf/urgent] perf data: " tip-bot for Jiri Olsa
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