From: Sandipan Das <sandipan.das@amd.com>
To: Jiri Olsa <jolsa@redhat.com>, acme@kernel.org
Cc: ravi.bangoria@amd.com, ananth.narayan@amd.com,
kim.phillips@amd.com, rrichter@amd.com,
linux-perf-users@vger.kernel.org, namhyung@kernel.org,
alexander.shishkin@linux.intel.com, mark.rutland@arm.com
Subject: Re: [RFC PATCH] tools/perf/x86: Use alternative format for AMD raw events
Date: Mon, 15 Nov 2021 15:28:45 +0530 [thread overview]
Message-ID: <9dc5cb10-2faf-a17b-ad4b-a22dbe688209@amd.com> (raw)
In-Reply-To: <YZE8SDkzq0OMcmhS@krava>
On 11/14/2021 10:11 PM, Jiri Olsa wrote:
> On Thu, Nov 11, 2021 at 06:26:46PM +0530, Sandipan Das wrote:
>
> SNIP
>
>> Before:
>>
>> $ sudo perf --debug perf-event-open stat -e ic_tag_hit_miss.all_instruction_cache_accesses sleep 1
>> ------------------------------------------------------------
>> perf_event_attr:
>> type 4
>> size 128
>> config 0x100001f8e
>> sample_type IDENTIFIER
>> read_format TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING
>> disabled 1
>> inherit 1
>> enable_on_exec 1
>> exclude_guest 1
>> ------------------------------------------------------------
>> [...]
>>
>> $ sudo perf --debug perf-event-open stat -e r1f18e sleep 1
>> ------------------------------------------------------------
>> perf_event_attr:
>> type 4
>> size 128
>> config 0x1f18e
>> sample_type IDENTIFIER
>> read_format TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING
>> disabled 1
>> inherit 1
>> enable_on_exec 1
>> exclude_guest 1
>> ------------------------------------------------------------
>> [...]
>>
>> $ sudo perf --debug perf-event-open stat -e r100001f8e sleep 1
>> ------------------------------------------------------------
>> perf_event_attr:
>> type 4
>> size 128
>> config 0x100001f8e
>> sample_type IDENTIFIER
>> read_format TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING
>> disabled 1
>> inherit 1
>> enable_on_exec 1
>> exclude_guest 1
>> ------------------------------------------------------------
>> [...]
>>
>> After:
>>
>> $ sudo perf --debug perf-event-open stat -e ic_tag_hit_miss.all_instruction_cache_accesses sleep 1
>> ------------------------------------------------------------
>> perf_event_attr:
>> type 4
>> size 128
>> config 0x100001f8e
>> sample_type IDENTIFIER
>> read_format TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING
>> disabled 1
>> inherit 1
>> enable_on_exec 1
>> exclude_guest 1
>> ------------------------------------------------------------
>> [...]
>>
>> $ sudo perf --debug perf-event-open stat -e r1f18e sleep 1
>> ------------------------------------------------------------
>> perf_event_attr:
>> type 4
>> size 128
>> config 0x100001f8e
>> sample_type IDENTIFIER
>> read_format TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING
>> disabled 1
>> inherit 1
>> enable_on_exec 1
>> exclude_guest 1
>> ------------------------------------------------------------
>> [...]
>>
>> $ sudo perf --debug perf-event-open stat -e r100001f8e sleep 1
>> ------------------------------------------------------------
>> perf_event_attr:
>> type 4
>> size 128
>> config 0x100001f8e
>> sample_type IDENTIFIER
>> read_format TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING
>> disabled 1
>> inherit 1
>> enable_on_exec 1
>> exclude_guest 1
>> ------------------------------------------------------------
>> [...]
>>
>> It is understandable that raw events must follow the native
>> PERF_CTL register format but it is worthwhile to pursue such
>> alternative formats for usability?
>
> good question.. I see raw events as a way to put to config whatever
> the user wants and IMO adding changes/quirks that silently changes
> config could create confusion and angry users ;-)
>
> I'd think that if user is composing/using raw events then using
> directly r100001f8e is not such a big deal?
>
Sure. Some of the confusion may be due to the fact that the man pages
for perf-{stat,record,top} state that raw events are "eventsel+umask".
While that is technically true, it does not describe the encoding
scheme (/sys/bus/event_source/devices/<pmu>/format/*)
Would another option be to update the man pages with a reference to
these sysfs files when describing raw events?
Something like:
diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
index 2d7df8703cf2..5dfdfeba594b 100644
--- a/tools/perf/Documentation/perf-record.txt
+++ b/tools/perf/Documentation/perf-record.txt
@@ -30,8 +30,10 @@ OPTIONS
- a symbolic event name (use 'perf list' to list all events)
- - a raw PMU event (eventsel+umask) in the form of rNNN where NNN is a
- hexadecimal event descriptor.
+ - a raw PMU event (eventsel+umask) in the form of rN..NN where N..NN
+ is a hexadecimal value representing the raw encoding with the layout
+ of the corresponding event control register as defined by entries in
+ /sys/bus/event_sources/devices/<pmu>/format/*
- a symbolic or raw PMU event followed by an optional colon
and a list of event modifiers, e.g., cpu-cycles:p. See the
> perhaps there was some some discussion about this that I missed?
>
I am not aware of one but may be Arnaldo has come across something
similar before?
- Sandipan
next prev parent reply other threads:[~2021-11-15 9:59 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-11 12:56 [RFC PATCH] tools/perf/x86: Use alternative format for AMD raw events Sandipan Das
2021-11-14 16:41 ` Jiri Olsa
2021-11-15 9:58 ` Sandipan Das [this message]
2021-11-16 4:38 ` kajoljain
2021-11-16 16:01 ` Kim Phillips
2021-11-17 14:13 ` kajoljain
2021-11-18 7:28 ` Sandipan Das
2021-11-18 16:51 ` Kim Phillips
2021-11-28 15:36 ` Jiri Olsa
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