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

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Message-ID: <20191011072154.GC6795@krava>
Date:   Fri, 11 Oct 2019 09:21:54 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     "Jin, Yao" <yao.jin@...ux.intel.com>
Cc:     Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>,
        Andi Kleen <ak@...ux.intel.com>, jolsa@...nel.org,
        peterz@...radead.org, mingo@...hat.com,
        alexander.shishkin@...ux.intel.com, Linux-kernel@...r.kernel.org,
        kan.liang@...el.com, yao.jin@...el.com
Subject: Re: [PATCH v1 0/2] perf stat: Support --all-kernel and --all-user

On Fri, Oct 11, 2019 at 10:50:35AM +0800, Jin, Yao wrote:
> 
> 
> On 10/10/2019 8:33 PM, Arnaldo Carvalho de Melo wrote:
> > Em Thu, Oct 10, 2019 at 04:33:57PM +0800, Jin, Yao escreveu:
> > > 
> > > 
> > > 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@...co ~]# 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. :)
> > 
> > Changes in semantics should be avoided, when we add an option already
> > present in some other tool, we should strive to keep the semantics, so
> > that people can reuse their knowledge and just switch tools to go from
> > sampling to counting, say.
> > 
> 
> Yes, that makes sense. We need to try our best to keep the original
> semantics. I will post a patch for perf-stat which just follows the
> semantics in perf-record.
> 
> > So if at all possible, and without having really looked deep in this
> > specific case, I would prefer that new semantics come with a new syntax,
> > would that be possible?
> > 
> 
> Yes, that's possible. Maybe we can use a new option for automatically adding
> two copies of the events (one copy for user and the other copy for kernel).
> The option something like "--all-space"?

some other ideas:

	--all
	--uk
	--both
	--full
	-e {cycles,cache-misses}:A,cycles,instructions:A
	-e {cycles,cache-misses}:B,cycles,instructions:B
	--duplicate-every-event-or-group-of-events-for-each-address-space ;-)

jirka