linux-kernel - Re: [PATCH] X86-32: Let gcc decide whether to inline memcpy was Re: New x86 warning

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Date:	Thu, 23 Apr 2009 15:09:01 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Joe Damato <ice799@...il.com>
CC:	Andi Kleen <andi@...stfloor.org>, Ingo Molnar <mingo@...e.hu>,
	Jeff Garzik <jeff@...zik.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, x86@...nel.org
Subject: Re: [PATCH] X86-32: Let gcc decide whether to inline memcpy was Re:
 	New x86 warning

Joe Damato wrote:
> 
> Looks like this thread is dead/dying, but figured I should reply with
> my test findings. The number of out-of-line calls (as determined by:
> make mrproper && make defconfig && make && objdump -d vmlinux | grep
> "call.*\<memset" | wc -l))
> 
> gcc 4.2.4 - withOUT memset patch: 20
> gcc 4.2.4 - with memset patch: 365
> 
> gcc 3.4 - withOUT memset patch: 17
> gcc 3.4 - with memset patch: 349
> 
> I'm guessing this is probably not acceptable, so I won't bother
> installing/trying gcc-3.2 unless anyone thinks that a 300+ increase in
> out-of-line calls is OK.
> 

Not unless it can be proven those calls are in non-performance-critical 
contexts.  That's a lot of work to go through, though.

	-hpa

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