Re: [PATCH v1 0/2] perf stat: Support --all-kernel and --all-user

From: "Jin, Yao" <yao.jin@linux.intel.com>
To: Jiri Olsa <jolsa@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>,
	Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>,
	jolsa@kernel.org, peterz@infradead.org, mingo@redhat.com,
	alexander.shishkin@linux.intel.com, Linux-kernel@vger.kernel.org,
	kan.liang@intel.com, yao.jin@intel.com
Subject: Re: [PATCH v1 0/2] perf stat: Support --all-kernel and --all-user
Date: Thu, 10 Oct 2019 16:33:57 +0800	[thread overview]
Message-ID: <9df9e60f-4998-32f2-f743-ebb0fdea4c0a@linux.intel.com> (raw)
In-Reply-To: <20191010080052.GB9616@krava>

On 10/10/2019 4:00 PM, Jiri Olsa wrote:
> On Thu, Oct 10, 2019 at 02:46:36PM +0800, Jin, Yao wrote:
>>
>>
>> On 10/1/2019 10:17 AM, Andi Kleen wrote:
>>>>> I think it's useful. Makes it easy to do kernel/user break downs.
>>>>> perf record should support the same.
>>>>
>>>> Don't we have this already with:
>>>>
>>>> [root@quaco ~]# perf stat -e cycles:u,instructions:u,cycles:k,instructions:k -a -- sleep 1
>>>
>>> This only works for simple cases. Try it for --topdown or multiple -M metrics.
>>>
>>> -Andi
>>>
>>
>> Hi Arnaldo, Jiri,
>>
>> We think it should be very useful if --all-user / --all-kernel can be
>> specified together, so that we can get a break down between user and kernel
>> easily.
>>
>> But yes, the patches for supporting this new semantics is much complicated
>> than the patch which just follows original perf-record behavior. I fully
>> understand this concern.
>>
>> So if this new semantics can be accepted, that would be very good. But if
>> you think the new semantics is too complicated, I'm also fine for posting a
>> new patch which just follows the perf-record behavior.
> 
> I still need to think a bit more about this.. did you consider
> other options like cloning of the perf_evlist/perf_evsel and
> changing just the exclude* bits? might be event worse actualy ;-)
> 

That should be another approach, but it might be a bit more complicated 
than just appending ":u"/":k" modifiers to the event name string.

> or maybe if we add modifier we could add extra events/groups
> within the parser.. like:
> 
>    "{cycles,instructions}:A,{cache-misses,cache-references}:A,cycles:A"
> 
> but that might be still more complicated then what you did
> 

Yes agree.

> also please add the perf record changes so we have same code
> and logic for both if we are going to change it
> 

If this new semantics can be accepted, I'd like to add perf record 
supporting as well. :)

Another difficulty for the new semantics is we need to create user and 
kernel stat type in runtime_stat rblist (see patch "perf stat: Support 
topdown with --all-kernel/--all-user"). That has to bring extra complexity.

Thanks
Jin Yao

> jirka
> 