Messages in this thread Patch in this message | | | Date | Thu, 2 Jul 2020 17:03:22 -0600 | From | Mathieu Poirier <> | Subject | Re: [PATCH 2/2] perf tools: Fix record failure when mixed with ARM SPE event |
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Hi Li,
On Tue, Jun 23, 2020 at 08:31:41PM +0800, Wei Li wrote: > When recording with cache-misses and arm_spe_x event, i found that > it will just fail without showing any error info if i put cache-misses > after arm_spe_x event. > > [root@localhost 0620]# perf record -e cache-misses -e \ > arm_spe_0/ts_enable=1,pct_enable=1,pa_enable=1,load_filter=1,\ > jitter=1,store_filter=1,min_latency=0/ sleep 1 > [ perf record: Woken up 1 times to write data ] > [ perf record: Captured and wrote 0.067 MB perf.data ] > [root@localhost 0620]# perf record -e \ > arm_spe_0/ts_enable=1,pct_enable=1,pa_enable=1,load_filter=1,jitter=1,\ > store_filter=1,min_latency=0/ -e cache-misses sleep 1 > [root@localhost 0620]# > > Finally, i found the reason is that the parameter 'arm_spe_pmu' passed to > arm_spe_recording_init() in auxtrace_record__init() is wrong. When the > arm_spe_x event is not the last event, 'arm_spe_pmus[i]' will be out of > bounds.
Yes, this indeed broken.
The current code can only work if the only event to be traced is an arm_spe_X, or if it is the last event to be specified. Otherwise the last event type will be checked against all the arm_spe_pmus[i]->types, none will match and an out of bound i index will be used in arm_spc_recording_init().
Since this problem is not easy to figure out please include the above explanation in the changelog.
> > It seems that the code can't support concurrent multiple different > arm_spe_x events currently. So add the code to check and record the > found 'arm_spe_pmu' to fix this issue. > > In fact, we don't support concurrent multiple same arm_spe_x events either, > that is checked in arm_spe_recording_options(), and it will show the > relevant info. > > Fixes: ffd3d18c20b8d ("perf tools: Add ARM Statistical Profiling Extensions (SPE) support") > Signed-off-by: Wei Li <liwei391@huawei.com> > --- > tools/perf/arch/arm/util/auxtrace.c | 10 +++++++++- > 1 file changed, 9 insertions(+), 1 deletion(-) > > diff --git a/tools/perf/arch/arm/util/auxtrace.c b/tools/perf/arch/arm/util/auxtrace.c > index 62b7b03d691a..7bb6f29e766c 100644 > --- a/tools/perf/arch/arm/util/auxtrace.c > +++ b/tools/perf/arch/arm/util/auxtrace.c > @@ -58,6 +58,7 @@ struct auxtrace_record > bool found_etm = false; > bool found_spe = false; > static struct perf_pmu **arm_spe_pmus; > + static struct perf_pmu *arm_spe_pmu;
As far as I can tell the "static" doesn't do anything.
> static int nr_spes = 0; > int i = 0; > > @@ -77,6 +78,13 @@ struct auxtrace_record > > for (i = 0; i < nr_spes; i++) { > if (evsel->core.attr.type == arm_spe_pmus[i]->type) { > + if (found_spe && (arm_spe_pmu != arm_spe_pmus[i])) { > + pr_err("Concurrent multiple SPE operation not currently supported\n"); > + *err = -EOPNOTSUPP; > + return NULL; > + }
Instead of the above, which as you rightly pointed out, is also done in arm_spe_recording_options() it might be best to just fix the "if (!nr_spes)" condition: if (!nr_spes || arm_spe_pmu) continue
Furthermore, instead of having a new arm_spe_pmu variable you could simply make found_spe a struct perf_pmu. That would be one less variable to take care of.
> + > + arm_spe_pmu = arm_spe_pmus[i]; > found_spe = true;
Last but not least do you know where the memory allocated for array arm_spe_pmus is released? If you can't find it either then we have a memory leak and it would be nice to have that fixed.
Regards Mathieu
PS: Leo Yan has spent a fair amount of time in the SPE code - please CC him on your next revision.
> break; > } > @@ -94,7 +102,7 @@ struct auxtrace_record > > #if defined(__aarch64__) > if (found_spe) > - return arm_spe_recording_init(err, arm_spe_pmus[i]); > + return arm_spe_recording_init(err, arm_spe_pmu); > #endif > > /* > -- > 2.17.1 >
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