Re: perf top for arm64?

From: Zenghui Yu <yuzenghui@huawei.com>
To: Jiri Olsa <jolsa@redhat.com>, John Garry <john.garry@huawei.com>
Cc: <mark.rutland@arm.com>, <peterz@infradead.org>,
	Linuxarm <linuxarm@huawei.com>,
	Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>,
	<linux-kernel@vger.kernel.org>,
	"linux-perf-users@vger.kernel.org"
	<linux-perf-users@vger.kernel.org>,
	<alexander.shishkin@linux.intel.com>, <mingo@redhat.com>,
	<namhyung@kernel.org>, <will@kernel.org>,
	<linux-arm-kernel@lists.infradead.org>,
	<wanghaibin.wang@huawei.com>
Subject: Re: perf top for arm64?
Date: Wed, 11 Dec 2019 10:36:39 +0800	[thread overview]
Message-ID: <0870e660-2511-ced0-7402-5ff389c4c281@huawei.com> (raw)
In-Reply-To: <20191210170841.GA23357@krava>

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@ubuntu:/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