Re: [PATCH v5 3/5] MIPS: perf: Reorganize contents of perf support files.

[David Daney <david.s.daney@gmail.com>]

On 09/23/2011 07:50 PM, Deng-Cheng Zhu wrote:
> 2011/9/23 David Daney<david.daney@cavium.com>
>> The contents of arch/mips/kernel/perf_event.c and
>> arch/mips/kernel/perf_event_mipsxx.c were divided in a seemingly ad
>> hoc manner, with the first including the second.
>>
>> I moved all the hardware counter support code to perf_event_mipsxx.c
>> and removed the gating #ifdefs to the Kconfig and Makefile.
>>
>> Now perf_event.c contains only the callchain support, everything else
>> is in perf_event_mipsxx.c
>>
> Sorry for my late comment. I personally don't think it's a bad idea to
> use the original gating #ifdefs, because it allows sharing common code
> among different types of MIPS PMUs. Also, using CPU types as compiling
> conditions seems make sense. If you move the common hunk to
> perf_event_mipsxx.c, other CPUs like loognson series will have to duplicate
> these stuff.
>

I disagree, and here is why:

Almost all the the code is mipsxx specific.

If Loongson has a PMU that can reuse this code, it can just be added to 
perf_event_mipsxx.c along with all the other mips compatible PMUs

If this is not feasible, then it can have its own file and and common 
code can be removed to a common place at that time.

In any event, I have not seen any Loongson PMU patches, if someone has 
such patches I would be happy to consider changes that would make the 
kernel as a whole cleaner.  But preventing cleanup and removal of a ton 
of #ifdefery in hope that Loongson patches may someday want something 
different is not what I would call a good way forward.

David Daney




> Deng-Cheng
>