linux-kernel - Re: [PATCH] perf/kvm: Guest Symbol Resolution for powerpc

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Message-ID: <56A1C6BF.2010602@linux.vnet.ibm.com>
Date:	Fri, 22 Jan 2016 11:35:51 +0530
From:	Ravi Bangoria <ravi.bangoria@...ux.vnet.ibm.com>
To:	Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:	linux-kernel@...r.kernel.org, hemant@...ux.vnet.ibm.com,
	naveen.n.rao@...ux.vnet.ibm.com, Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH] perf/kvm: Guest Symbol Resolution for powerpc

Hi Arnaldo,

On Wednesday 13 January 2016 10:29 PM, Arnaldo Carvalho de Melo wrote:
> Em Tue, Dec 29, 2015 at 03:38:40PM +0530, Ravi Bangoria escreveu:
>> 'perf kvm {record|report}' is used to record and report the profiled
>> performance of any workload on a guest. From the host, we can collect
>> guest kernel statistics which is useful in finding out any contentions
>> in guest kernel symbols for a certain workload.
>> This feature is not available on powerpc because 'perf' relies on the
>> 'cycles' event (a PMU event) to profile the guest. However, for powerpc,
>> this can't be used from the host because the PMUs are controlled by the
>> guest rather than the host.
> Without entering the realms if the approach is the right one, which I
> leave to PowerPC experts, Ingo, PeterZ, etc:
>
> So, in these cases, please break this into a series, where you, for
> instance, will add that extra evsel parameter to the functions that will
> ultimately use it to extract those event fields, that should be a
> separate patch, so that when reviewing the "meat" of your patch we can
> quickly see what it does, not having to extract that from leg work.
>
> Two other patches should introduce arch__get_{ip,cpumode}().
>
> - Arnaldo

Thanks for suggestion. I've sent v2 with changes you suggested.

Can you please take a look.

Regards,
Ravi