linux-kernel - Re: [PATCH v2 2/3] perf kvm: enable record|report feature on powerpc

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Date:	Tue, 2 Feb 2016 14:36:48 +0530
From:	Ravi Bangoria <ravi.bangoria@...ux.vnet.ibm.com>
To:	Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:	mingo@...nel.org, peterz@...radead.org,
	linux-kernel@...r.kernel.org, hemant@...ux.vnet.ibm.com,
	naveen.n.rao@...ux.vnet.ibm.com
Subject: Re: [PATCH v2 2/3] perf kvm: enable record|report feature on powerpc

HI acme,

On Tuesday 02 February 2016 02:36 AM, Arnaldo Carvalho de Melo wrote:
> Em Fri, Jan 22, 2016 at 11:28:11AM +0530, Ravi Bangoria escreveu:
>> +	return event->header.misc & PERF_RECORD_MISC_CPUMODE_MASK;
>> +}
> This hunk and the next should be on the previous patch, that is not even
> compiling...
>
> You have to compile patch by patch, we can't just test at the end of a
> patchkit like this, this destroys bisection ;-\

Didn't aware about that. Will take care of compiling each patch
separately next time onwards.

> Also you first need to put in place a way to override how to obtain the
> cpumode, then you should use it.
>
> Also this mode doesn't look feasible at all, think about processing
> perf.data files generated in !powerpc systems being analysed in a
> powerpc system. This has to be dependend on the architecture of the
> machine where the perf.data file was recorded, not on the archictecture
> of the machine the binary was built for.

Valid point.

I'll re-think about approach in this case.

> It is only when you do live analysis, like with 'perf trace' and 'perf
> top' that its guaranteed to be all on the same machine.
>
> IIRC in one of the patches in this series you introduce and use a
> library function on the same patch, please break it into two patches as
> well, lemme see what is the name...
>
> Yeah, it is also in this patch:
>
> perf_evlist__arch_add_default(struct perf_evlist *evlist)
>
> Please add this in a separate patch, stating in the changeset comment
> why it is needed and how architectures can override it.

Will do that. Thanks for reviewing.

Regards,
Ravi