linux-kernel - Re: [RFC 4/4] perf kvm: Fix output fields instead of 'trace' for perf kvm report on powerpc

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Message-ID: <20160302162220.GS3604@kernel.org>
Date:	Wed, 2 Mar 2016 13:22:20 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Ravi Bangoria <ravi.bangoria@...ux.vnet.ibm.com>
Cc:	linux-kernel@...r.kernel.org, hemant@...ux.vnet.ibm.com,
	naveen.n.rao@...ux.vnet.ibm.com
Subject: Re: [RFC 4/4] perf kvm: Fix output fields instead of 'trace' for
 perf kvm report on powerpc

Em Wed, Mar 02, 2016 at 09:16:48PM +0530, Ravi Bangoria escreveu:
> Thanks Arnaldo,
> 
> Please find my comments.
> 
> On Wednesday 02 March 2016 07:55 PM, Arnaldo Carvalho de Melo wrote:
> >Em Wed, Feb 24, 2016 at 02:37:45PM +0530, Ravi Bangoria escreveu:
> >>  		use_browser = 0;
> >>+	if (!field_order &&
> >>+	    is_perf_data_reorded_on_ppc(session->evlist) &&
> >>+	    perf_guest_only())
> >>+		field_order = "overhead,comm,dso,sym";
> >>+
> >Can you please do it as:
> >
> >__weak void arch__override_field_order(struct perf_evlist *evlist, const char **field_order)
> >{
> >}
> 
> So you mean like this - Just implement only weak function and move code into
> it?
> ie. No strong implementation at this point of time.
> 
> Like,
> 
> __weak void arch__override_field_order(struct perf_evlist *evlist, const
> char **f_order)
> {
>     if (!field_order &&
>         is_perf_data_reorded_on_ppc(session->evlist) &&

Oh, I see, ugh, when running on x86_64 we wouldn't use this, so we need
to have per arch default field orders, now I have to recall why is it
that we need this per-arch field order :-\

- Arnaldo

>         perf_guest_only())
>             *field_order = "overhead,comm,dso,sym";
> }
> 
> Then I can do that.
> 
> But if you are proposing to implement a strong function and move this code
> into in, then we won't be able to enable cross arch reporting.
> 
> >
> >This way we don't see any arch specific stuff in the tool, also I
> >haven't seen any doc update, are you sure nothing needs to be added to
> >tools/perf/Documentaton/ for any of these patches?
> >
> >I think this needs to be documented further, probably in
> >tools/perf/design.txt too?
> 
> Yes, I'll do this in next version.
> 
> Regards,
> Ravi