linux-kernel - Re: [PATCH 09/14] perf, x86: use LBR for PEBS IP+1 fixup

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Date:	Thu, 04 Mar 2010 15:54:59 -0500
From:	Masami Hiramatsu <mhiramat@...hat.com>
To:	Peter Zijlstra <peterz@...radead.org>
CC:	mingo@...e.hu, linux-kernel@...r.kernel.org, paulus@...ba.org,
	eranian@...gle.com, robert.richter@....com, fweisbec@...il.com,
	Arnaldo Carvalho de Melo <acme@...radead.org>,
	Yanmin Zhang <yanmin_zhang@...ux.intel.com>
Subject: Re: [PATCH 09/14] perf, x86: use LBR for PEBS IP+1 fixup

Peter Zijlstra wrote:
> On Thu, 2010-03-04 at 11:21 -0500, Masami Hiramatsu wrote:
>> Peter Zijlstra wrote:
> 
>>> +#define perf_misc_flags(regs)				\
>>> +({	int misc = 0;					\
>>> +	if (user_mode(regs))				\
>>> +		misc |= PERF_RECORD_MISC_USER;		\
>>> +	else						\
>>> +		misc |= PERF_RECORD_MISC_KERNEL;	\
>>> +	if (regs->flags & PERF_EFLAGS_EXACT)		\
>>> +		misc |= PERF_RECORD_MISC_EXACT;		\
>>> +	misc; })
>>> +
>>> +#define perf_instruction_pointer(regs)	((regs)->ip)
>>
>> Hmm, why don't you use instruction_pointer() defined in asm/ptrace.h?
>> And I couldn't find any user of this macro in this patch...
> 
> perf_instruction_pointer() is used in kernel/perf_event.c, and yeah I
> could have used instruction_pointer() but that's yet another wrapper.
> 
> Anyway, Yanmin is poking at doing kvm-guest profiling and will likely
> rewrite all of the perf_misc() and perf_instruction_pointer() stuff
> soon.

Hmm, still I can't find where it is used (in your patches).
Anyway, would you mean that perf_instruction_pointer() will
have different implementation by Yanmin?

Thank you,

-- 
Masami Hiramatsu
e-mail: mhiramat@...hat.com
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