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From: Balbir Singh <balbir@linux.vnet.ibm.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>,
	linuxppc-dev@ozlabs.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] Fake NUMA emulation for PowerPC
Date: Sat, 08 Dec 2007 03:33:09 +0530	[thread overview]
Message-ID: <4759C31D.30003@linux.vnet.ibm.com> (raw)
In-Reply-To: <200712072258.19331.arnd@arndb.de>

Arnd Bergmann wrote:
> On Friday 07 December 2007, Balbir Singh wrote:
>> Balbir Singh wrote:
>>> Geert Uytterhoeven wrote:
>>>> On Sat, 8 Dec 2007, Balbir Singh wrote:
>>>>> +   if (strstr(p, "fake="))
>>>>> +           cmdline = p + 5;        /* 5 is faster than strlen("fake=") */
>>>> Really? My gcc is smart enough to replace the `strlen("fake=")' by 5, even
>>>> without -O.
>>>>
>>> Thanks for pointing that out, but I am surprised that a compiler would
>>> interpret library routines like strlen.
>>>
>> I just tested it and it turns out that you are right. I'll go hunt to
>> see where gcc gets its magic powers from.
>>
> 
> Even if it wasn't: Why the heck would you want to optimize this? The function
> is run _once_ at boot time and the object code gets thrown away afterwards!
> 
> 	Arnd <><

Cause, I see no downside of doing it. The strlen of fake= is fixed.
But having said that, I am not a purist about the approach, I just want
cmdline to point after "fake="

-- 
	Warm Regards,
	Balbir Singh
	Linux Technology Center
	IBM, ISTL

WARNING: multiple messages have this Message-ID (diff)
From: Balbir Singh <balbir@linux.vnet.ibm.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: linuxppc-dev@ozlabs.org,
	Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] Fake NUMA emulation for PowerPC
Date: Sat, 08 Dec 2007 03:33:09 +0530	[thread overview]
Message-ID: <4759C31D.30003@linux.vnet.ibm.com> (raw)
In-Reply-To: <200712072258.19331.arnd@arndb.de>

Arnd Bergmann wrote:
> On Friday 07 December 2007, Balbir Singh wrote:
>> Balbir Singh wrote:
>>> Geert Uytterhoeven wrote:
>>>> On Sat, 8 Dec 2007, Balbir Singh wrote:
>>>>> +   if (strstr(p, "fake="))
>>>>> +           cmdline = p + 5;        /* 5 is faster than strlen("fake=") */
>>>> Really? My gcc is smart enough to replace the `strlen("fake=")' by 5, even
>>>> without -O.
>>>>
>>> Thanks for pointing that out, but I am surprised that a compiler would
>>> interpret library routines like strlen.
>>>
>> I just tested it and it turns out that you are right. I'll go hunt to
>> see where gcc gets its magic powers from.
>>
> 
> Even if it wasn't: Why the heck would you want to optimize this? The function
> is run _once_ at boot time and the object code gets thrown away afterwards!
> 
> 	Arnd <><

Cause, I see no downside of doing it. The strlen of fake= is fixed.
But having said that, I am not a purist about the approach, I just want
cmdline to point after "fake="

-- 
	Warm Regards,
	Balbir Singh
	Linux Technology Center
	IBM, ISTL

  reply	other threads:[~2007-12-07 22:03 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-12-07 21:14 [PATCH] Fake NUMA emulation for PowerPC Balbir Singh
2007-12-07 21:14 ` Balbir Singh
2007-12-07 21:28 ` Olof Johansson
2007-12-07 21:35   ` Balbir Singh
2007-12-07 21:55     ` Kumar Gala
2007-12-07 22:12       ` Balbir Singh
2007-12-07 22:15         ` Kumar Gala
2007-12-07 22:18           ` Balbir Singh
2007-12-07 23:10         ` David Rientjes
2007-12-07 23:10           ` David Rientjes
2007-12-08  4:22           ` Balbir Singh
2007-12-08  4:22             ` Balbir Singh
2007-12-09 13:16             ` Pavel Machek
2007-12-09 13:16               ` Pavel Machek
2007-12-09 13:20               ` Balbir Singh
2007-12-09 13:20                 ` Balbir Singh
2007-12-07 23:06   ` David Rientjes
2007-12-07 23:06     ` David Rientjes
2007-12-07 21:30 ` Geert Uytterhoeven
2007-12-07 21:33   ` Dave Quigley
2007-12-07 21:35   ` Balbir Singh
2007-12-07 21:43     ` Balbir Singh
2007-12-07 21:58       ` Arnd Bergmann
2007-12-07 21:58         ` Arnd Bergmann
2007-12-07 22:03         ` Balbir Singh [this message]
2007-12-07 22:03           ` Balbir Singh
2007-12-07 22:01 ` Arnd Bergmann
2007-12-07 22:01   ` Arnd Bergmann
2007-12-07 22:22   ` Balbir Singh
2007-12-07 22:11 ` Nathan Lynch
2007-12-07 22:26   ` Balbir Singh
2007-12-07 23:11     ` David Rientjes
2007-12-07 23:11       ` David Rientjes
2007-12-08  4:32       ` Balbir Singh
2007-12-08  4:45         ` David Rientjes

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