Re: [PATCH v3 40/71] ARC: OProfile support

From: Vineet Gupta
Date: Wed Jan 30 2013 - 06:48:35 EST


On Wednesday 30 January 2013 04:24 PM, James Hogan wrote:
> On 30/01/13 06:34, Vineet Gupta wrote:
>> On Tuesday 29 January 2013 10:35 PM, James Hogan wrote:
>>> Hi Vineet,
>>>
>>> You don't appear to define CONFIG_HW_PERF_EVENTS, so
>>> include/linux/oprofile.h will presumably define oprofile_perf_init as
>>> just a pr_info(...); return -ENODEV;
>>>
>>> Similarly drivers/oprofile/oprofile_perf.o doesn't seem to be being built.
>>>
>>> I'm probably missing something somewhere?
>> Not much :-)
>>
>> oprofile_arch_init() failure causes oprofile to fall back to timer based PC only
>> sampling - for coarse grained profiling. I'll soon be starting on integratign the
>> hardware counter support to both oprofile/perf.
> Okay cool. It's just slightly misleading for anybody copying the code
> that it calls oprofile_perf_init which is known never to do anything
> :-). Maybe it's worth adding a comment in there to clarify.

I think banner comment in oprofile.h for oprofile_arch_init() needs to document
that "in case it fails, oprofile switches to timer mode PC sampling".
But nevertheless it's good idea to add that clarification in my code anyways.

>
> Reviewed-by: James Hogan <james.hogan@xxxxxxxxxx>

Thx,
-Vineet
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