From: David Miller <davem@davemloft.net>
To: paulus@samba.org
Cc: fweisbec@gmail.com, mingo@elte.hu, linux-arch@vger.kernel.org
Subject: Re: perf_arch_fetch_caller_regs...
Date: Thu, 18 Mar 2010 21:51:34 -0700 (PDT) [thread overview]
Message-ID: <20100318.215134.200355129.davem@davemloft.net> (raw)
In-Reply-To: <20100319043202.GA3850@brick.ozlabs.ibm.com>
From: Paul Mackerras <paulus@samba.org>
Date: Fri, 19 Mar 2010 15:32:02 +1100
> On Thu, Mar 18, 2010 at 09:02:41PM -0700, David Miller wrote:
>> I noticed that the powerpc assembler Paul posted the past few days
>> ignores this "ip" arg passed down and computes it by hand as it
>> walks up the stack chain in assembler. PowerPC therefore might be
>> getting similar inefficiences due to this CALLER_ADDR? stuff.
>
> Well, it would except that CALLER_ADDR1, 2, etc. turn into (0) on
> powerpc because we use the generic definition and we don't define
> CONFIG_FRAME_POINTER (it's meaningless on powerpc because the ABI
> defines that each stack frame always has a pointer to the previous
> frame).
>
> I should fix CALLER_ADDRx on powerpc one day, then we will have the
> extra inefficiency.
Gosh, that CONFIG_FRAME_POINTER dependency is 'nifty', how does the
CALLER_ADDR{1,2} usage made by the scheduler tracepoints work on
powerpc then?
I suppose I could define HAVE_ARCH_CALLER_ADDR and optimize them
on sparc64, similar to what SH is doing.
prev parent reply other threads:[~2010-03-19 4:51 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-19 4:02 perf_arch_fetch_caller_regs David Miller
2010-03-19 4:24 ` perf_arch_fetch_caller_regs Frederic Weisbecker
2010-03-19 4:47 ` perf_arch_fetch_caller_regs David Miller
2010-03-19 4:32 ` perf_arch_fetch_caller_regs Paul Mackerras
2010-03-19 4:51 ` David Miller [this message]
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