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Message-ID: <d791209c-c2b8-301c-a14e-3054ce4a11c7@intel.com>
Date: Mon, 20 Feb 2017 17:39:43 +0200
From: Adrian Hunter <adrian.hunter@...el.com>
To: Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Arnaldo Carvalho de Melo <acme@...radead.org>
Cc: linux-kernel@...r.kernel.org, vince@...ter.net, eranian@...gle.com,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Ingo Molnar <mingo@...hat.com>
Subject: Re: [PATCH 0/4] perf, pt, coresight: AUX flags and VMX update
On 20/02/17 17:18, Alexander Shishkin wrote:
> Alexander Shishkin <alexander.shishkin@...ux.intel.com> writes:
>
>> With the vmm_exclusive=0, PT seems to be much more usable on BDW now. This
>> patchset does three things:
>> * adds a flag to PERF_RECORD_AUX, signalling that a transaction has gaps
>> in it (due to VMX root mode kicking in),
>
> Hi Arnaldo & Adrian,
>
> In the above context, will something like this be fine?
Looks fine to me.
Acked-by: Adrian Hunter <adrian.hunter@...el.com>
>
> Regards,
> --
> Alex
>
>>>From 5aba03e79c1119408b44435af8c4cee2480b0775 Mon Sep 17 00:00:00 2001
> From: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
> Date: Mon, 20 Feb 2017 17:08:53 +0200
> Subject: [PATCH] perf tools: Handle partial AUX records and print a warning
>
> This patch decodes the 'partial' flag in AUX records and prints
> a warning to the user, so that they don't have to guess why their
> PT traces contain gaps (or missing altogether):
>
>> Warning:
>> AUX data had gaps in it 6 times out of 8!
>>
>> Are you running a KVM guest in the background?
>
> Currently this is the only reason for partial records.
>
> Cc: Adrian Hunter <adrian.hunter@...el.com>
> Signed-off-by: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
> ---
> tools/include/uapi/linux/perf_event.h | 1 +
> tools/perf/util/event.c | 5 +++--
> tools/perf/util/event.h | 1 +
> tools/perf/util/session.c | 17 ++++++++++++++---
> 4 files changed, 19 insertions(+), 5 deletions(-)
>
> diff --git a/tools/include/uapi/linux/perf_event.h b/tools/include/uapi/linux/perf_event.h
> index c66a485a24..8306415207 100644
> --- a/tools/include/uapi/linux/perf_event.h
> +++ b/tools/include/uapi/linux/perf_event.h
> @@ -885,6 +885,7 @@ enum perf_callchain_context {
> */
> #define PERF_AUX_FLAG_TRUNCATED 0x01 /* record was truncated to fit */
> #define PERF_AUX_FLAG_OVERWRITE 0x02 /* snapshot from overwrite mode */
> +#define PERF_AUX_FLAG_PARTIAL 0x04 /* record contains gaps */
>
> #define PERF_FLAG_FD_NO_GROUP (1UL << 0)
> #define PERF_FLAG_FD_OUTPUT (1UL << 1)
> diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
> index 4ea7ce72ed..ba193cd019 100644
> --- a/tools/perf/util/event.c
> +++ b/tools/perf/util/event.c
> @@ -1153,11 +1153,12 @@ int perf_event__process_exit(struct perf_tool *tool __maybe_unused,
>
> size_t perf_event__fprintf_aux(union perf_event *event, FILE *fp)
> {
> - return fprintf(fp, " offset: %#"PRIx64" size: %#"PRIx64" flags: %#"PRIx64" [%s%s]\n",
> + return fprintf(fp, " offset: %#"PRIx64" size: %#"PRIx64" flags: %#"PRIx64" [%s%s%s]\n",
> event->aux.aux_offset, event->aux.aux_size,
> event->aux.flags,
> event->aux.flags & PERF_AUX_FLAG_TRUNCATED ? "T" : "",
> - event->aux.flags & PERF_AUX_FLAG_OVERWRITE ? "O" : "");
> + event->aux.flags & PERF_AUX_FLAG_OVERWRITE ? "O" : "",
> + event->aux.flags & PERF_AUX_FLAG_PARTIAL ? "P" : "");
> }
>
> size_t perf_event__fprintf_itrace_start(union perf_event *event, FILE *fp)
> diff --git a/tools/perf/util/event.h b/tools/perf/util/event.h
> index c735c53a26..d7e53fe176 100644
> --- a/tools/perf/util/event.h
> +++ b/tools/perf/util/event.h
> @@ -269,6 +269,7 @@ struct events_stats {
> u64 total_lost;
> u64 total_lost_samples;
> u64 total_aux_lost;
> + u64 total_aux_partial;
> u64 total_invalid_chains;
> u32 nr_events[PERF_RECORD_HEADER_MAX];
> u32 nr_non_filtered_samples;
> diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
> index 4cdbc8f5f1..abdb797fa4 100644
> --- a/tools/perf/util/session.c
> +++ b/tools/perf/util/session.c
> @@ -1258,9 +1258,12 @@ static int machines__deliver_event(struct machines *machines,
> case PERF_RECORD_UNTHROTTLE:
> return tool->unthrottle(tool, event, sample, machine);
> case PERF_RECORD_AUX:
> - if (tool->aux == perf_event__process_aux &&
> - (event->aux.flags & PERF_AUX_FLAG_TRUNCATED))
> - evlist->stats.total_aux_lost += 1;
> + if (tool->aux == perf_event__process_aux) {
> + if (event->aux.flags & PERF_AUX_FLAG_TRUNCATED)
> + evlist->stats.total_aux_lost += 1;
> + if (event->aux.flags & PERF_AUX_FLAG_PARTIAL)
> + evlist->stats.total_aux_partial += 1;
> + }
> return tool->aux(tool, event, sample, machine);
> case PERF_RECORD_ITRACE_START:
> return tool->itrace_start(tool, event, sample, machine);
> @@ -1548,6 +1551,14 @@ static void perf_session__warn_about_errors(const struct perf_session *session)
> stats->nr_events[PERF_RECORD_AUX]);
> }
>
> + if (session->tool->aux == perf_event__process_aux &&
> + stats->total_aux_partial != 0) {
> + ui__warning("AUX data had gaps in it %" PRIu64 " times out of %u!\n\n"
> + "Are you running a KVM guest in the background?\n\n",
> + stats->total_aux_partial,
> + stats->nr_events[PERF_RECORD_AUX]);
> + }
> +
> if (stats->nr_unknown_events != 0) {
> ui__warning("Found %u unknown events!\n\n"
> "Is this an older tool processing a perf.data "
>
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