linux-kernel - Re: perf top for arm64?

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Date:   Wed, 11 Dec 2019 10:36:39 +0800
From:   Zenghui Yu <yuzenghui@...wei.com>
To:     Jiri Olsa <jolsa@...hat.com>, John Garry <john.garry@...wei.com>
CC:     <mark.rutland@....com>, <peterz@...radead.org>,
        Linuxarm <linuxarm@...wei.com>,
        Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>,
        <linux-kernel@...r.kernel.org>,
        "linux-perf-users@...r.kernel.org" <linux-perf-users@...r.kernel.org>,
        <alexander.shishkin@...ux.intel.com>, <mingo@...hat.com>,
        <namhyung@...nel.org>, <will@...nel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <wanghaibin.wang@...wei.com>
Subject: Re: perf top for arm64?

Hi John,

On 2019/12/11 1:08, Jiri Olsa wrote:
> On Tue, Dec 10, 2019 at 04:52:52PM +0000, John Garry wrote:
>> On 10/12/2019 16:36, Jiri Olsa wrote:
>>> On Tue, Dec 10, 2019 at 04:13:49PM +0000, John Garry wrote:
>>>> Hi all,
>>>>
>>>> I find to my surprise that "perf top" does not work for arm64:
>>>>
>>>> root@...ntu:/home/john/linux# tools/perf/perf top
>>>> Couldn't read the cpuid for this machine: No such file or directory
>>>
>>
>> Hi Jirka,
>>
>>> there was recent change that check on cpuid and quits:
>>>     608127f73779 perf top: Initialize perf_env->cpuid, needed by the per arch annotation init routine
>>>
>>
>> ok, this is new code. I obviously didn't check the git history...
>>
>> But, apart from this, there are many other places where get_cpuid() is
>> called. I wonder what else we're missing out on, and whether we should still
>> add it.
> 
> right, I was just wondering how come vendor events are working for you,
> but realized we have get_cpuid_str being called in there ;-)
> 
> I think we should add it as you have it prepared already,
> could you post it with bigger changelog that would explain
> where it's being used for arm?

I've also seen the similar problem when I was looking to add support
for 'perf kvm stat' on arm64 [1] (which though got stuck due to some
other reasons for a very long time :(

It would be great if your patch can address this issue!


[1] https://lore.kernel.org/patchwork/patch/1087531/


Thanks,
Zenghui