From:   John Garry <john.garry@huawei.com>
Subject: Re: [RFC PATCH 1/1] perf arm64: Implement --topdown with metrics
To:     Andrew Kilroy <andrew.kilroy@arm.com>,
        Ian Rogers <irogers@google.com>
CC:     <linux-kernel@vger.kernel.org>, <linux-perf-users@vger.kernel.org>,
        <acme@kernel.org>, Will Deacon <will@kernel.org>,
        Mathieu Poirier <mathieu.poirier@linaro.org>,
        Leo Yan <leo.yan@linaro.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@redhat.com>,
        "Namhyung Kim" <namhyung@kernel.org>,
        <linux-arm-kernel@lists.infradead.org>
References: <4c375d34-bf20-496d-22fc-aed8597126e2@huawei.com>
 <20211214184240.24215-1-andrew.kilroy@arm.com>
 <20211214184240.24215-2-andrew.kilroy@arm.com>
 <CAP-5=fXJeH0ZvcHPa20N5KfLwnYSw29rpK3OrnvE0o3u-vGTLA@mail.gmail.com>
 <b1640897-10d7-c11e-4a7a-d17633916c8e@huawei.com>
 <d91a1b98-2c2b-a961-543f-d540b3c7a146@arm.com>
Message-ID: <0a14914c-063d-f9ae-be49-ae9cc6aa7ff1@huawei.com>
Date:   Wed, 15 Dec 2021 12:53:16 +0000
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101
 Thunderbird/68.12.1
MIME-Version: 1.0
In-Reply-To: <d91a1b98-2c2b-a961-543f-d540b3c7a146@arm.com>
Content-Type: text/plain; charset="utf-8"; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 8bit
Precedence: bulk

>> In addition we could also add a --topdown arg to force using JSON 
>> metricgroups.
>>
> 
> What arg do think would be supplied?

something like -json or -metricgroup, meaning "Use pmu-events metric 
events to calculate topdown results rather than kernel CPU PMU events. 
This is default fallback if the kernel CPU PMU does not support topdown 
events"

> 
>> Did you actually test this patch? I have something experimental 
>> working from some time ago, and it was more complicated than this. I 
>> need to check the code again...
>>
> 
> I got stats back from this implementation, yes.  Let me know if there's 
> things my patch isn't catering for.

I'll give it a spin...

Thanks,
John