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Subject: Re: [PATCH v2 07/27] perf evlist: Hybrid event uses its own cpus
To:     Jiri Olsa <jolsa@redhat.com>
Cc:     acme@kernel.org, jolsa@kernel.org, peterz@infradead.org,
        mingo@redhat.com, alexander.shishkin@linux.intel.com,
        Linux-kernel@vger.kernel.org, ak@linux.intel.com,
        kan.liang@intel.com, yao.jin@intel.com
References: <20210311070742.9318-1-yao.jin@linux.intel.com>
 <20210311070742.9318-8-yao.jin@linux.intel.com> <YEu9wl4FcF+AoRTy@krava>
From:   "Jin, Yao" <yao.jin@linux.intel.com>
Message-ID: <d5f20c67-1e5f-e5c1-4665-717468dc88be@linux.intel.com>
Date:   Mon, 15 Mar 2021 09:25:18 +0800
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Hi Jiri,

On 3/13/2021 3:15 AM, Jiri Olsa wrote:
> On Thu, Mar 11, 2021 at 03:07:22PM +0800, Jin Yao wrote:
>> On hybrid platform, atom events can be only enabled on atom CPUs. Core
>> events can be only enabled on core CPUs. So for a hybrid event, it can
>> be only enabled on it's own CPUs.
>>
>> But the problem for current perf is, the cpus for evsel (via PMU sysfs)
>> have been merged to evsel_list->core.all_cpus. It might be all CPUs.
>>
>> So we need to figure out one way to let the hybrid event only use it's
>> own CPUs.
>>
>> The idea is to create a new evlist__invalidate_all_cpus to invalidate
>> the evsel_list->core.all_cpus then evlist__for_each_cpu returns cpu -1
>> for hybrid evsel. If cpu is -1, hybrid evsel will use it's own cpus.
> 
> that's wild.. I don't understand when you say we don't have
> cpus for evsel, because they have been merged.. each evsel
> has evsel->core.own_cpus coming from pmu->cpus, right?
> 
> why can't you just filter out cpus that are in there?
> 
> jirka
> 

Yes, you're right. This patch is wide and actually it's not very necessary.

The current framework has processed the cpus for evsel well even for hybrid evsel. So this patch can 
be dropped.

Thanks
Jin Yao