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From: Segher Boessenkool <segher@kernel.crashing.org>
To: Paul Mackerras <paulus@samba.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	linuxppc-dev@ozlabs.org
Subject: Re: [PATCH] add strncmp to PowerPC
Date: Wed, 5 Mar 2008 06:26:06 +0100	[thread overview]
Message-ID: <d495403c2b5f700be085c965746cd211@kernel.crashing.org> (raw)
In-Reply-To: <18382.7074.69060.661720@cargo.ozlabs.ibm.com>

>> Do we have any indication that it performs better than the C one ?
>
> I would expect it to, given that the assembler one has two branches in
> the per-byte loop compared to 3 in the C version.

But really, does it matter for strncmp() in the kernel?

Anyway, this asm code has bugs, as do both the current C version in the
kernel, and the code I posted.  We need to do better :-)


Segher

WARNING: multiple messages have this Message-ID (diff)
From: Segher Boessenkool <segher@kernel.crashing.org>
To: Paul Mackerras <paulus@samba.org>
Cc: benh@kernel.crashing.org, LKML <linux-kernel@vger.kernel.org>,
	linuxppc-dev@ozlabs.org, Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [PATCH] add strncmp to PowerPC
Date: Wed, 5 Mar 2008 06:26:06 +0100	[thread overview]
Message-ID: <d495403c2b5f700be085c965746cd211@kernel.crashing.org> (raw)
In-Reply-To: <18382.7074.69060.661720@cargo.ozlabs.ibm.com>

>> Do we have any indication that it performs better than the C one ?
>
> I would expect it to, given that the assembler one has two branches in
> the per-byte loop compared to 3 in the C version.

But really, does it matter for strncmp() in the kernel?

Anyway, this asm code has bugs, as do both the current C version in the
kernel, and the code I posted.  We need to do better :-)


Segher


  reply	other threads:[~2008-03-05  5:26 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-02-29 16:04 [PATCH] add strncmp to PowerPC Steven Rostedt
2008-03-01  3:04 ` Benjamin Herrenschmidt
2008-03-01  3:04   ` Benjamin Herrenschmidt
2008-03-01  3:56   ` Steven Rostedt
2008-03-01  3:56     ` Steven Rostedt
2008-03-03  9:54     ` Gabriel Paubert
2008-03-03  9:54       ` Gabriel Paubert
2008-03-03 10:10       ` Andreas Schwab
2008-03-03 10:10         ` Andreas Schwab
2008-03-03 19:08       ` Segher Boessenkool
2008-03-03 19:08         ` Segher Boessenkool
2008-03-05  4:03   ` Paul Mackerras
2008-03-05  4:03     ` Paul Mackerras
2008-03-05  5:26     ` Segher Boessenkool [this message]
2008-03-05  5:26       ` Segher Boessenkool
2008-03-05  5:39       ` Paul Mackerras
2008-03-05  5:39         ` Paul Mackerras
2008-03-05  7:01         ` Segher Boessenkool
2008-03-05  7:01           ` Segher Boessenkool

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