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From: Raja R Harinath <harinath@hurrynot.org>
To: linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/3] lib: vsprintf: added a put_dec() test and benchmark tool
Date: Fri, 06 Aug 2010 21:27:09 +0530	[thread overview]
Message-ID: <8762zn7mzu.fsf@hariville.hurrynot.org> (raw)
In-Reply-To: <op.vg0csju97p4s8u@pikus>

Hi,

Michał Nazarewicz <m.nazarewicz@samsung.com> writes:

> On Fri, 06 Aug 2010 07:10:06 +0200, Denys Vlasenko <vda.linux@googlemail.com> wrote:
>
>> On Friday 06 August 2010 00:38, Michal Nazarewicz wrote:
>>> This commit adds a test application for the put_dec() and
>>> family of functions that are used by the previous two commits.
>>>
>>> Signed-off-by: Michal Nazarewicz <mina86@mina86.com>
>>
>>> +put-dec-test: put-dec-test.c
>>> +	exec $(CC) $(CFLAGS) -o $@ $<
>>
>> (1) Why exec?
>
> Micro Makefile optimisation -- saves us a fork().

I don't think it's worth it.  The use of 'exec' will force make to
invoke the shell, while without the exec, make has an opportunity to
optimize out the shell invocation completely [1].  Forcing the use of a
shell to avoid a fork() sounds like a terrible trade-off.

- Hari

[1] See, for instance, construct_command_argv_internal() in

  http://cvs.savannah.gnu.org/viewvc/make/job.c?root=make&view=markup


  reply	other threads:[~2010-08-06 15:58 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-08-05 22:38 [PATCH 1/3] lib: vsprintf: optimised put_dec_trunc() and put_dec_full() Michal Nazarewicz
2010-08-05 22:38 ` [PATCH 2/3] lib: vsprintf: optimised put_dec() for 32-bit machines Michal Nazarewicz
2010-08-05 22:38   ` [PATCH 3/3] lib: vsprintf: added a put_dec() test and benchmark tool Michal Nazarewicz
2010-08-06  5:10     ` Denys Vlasenko
2010-08-06  8:34       ` Michał Nazarewicz
2010-08-06 15:57         ` Raja R Harinath [this message]
2010-08-06 19:26         ` Denys Vlasenko
2010-08-06 20:58           ` Michal Nazarewicz
2010-08-06  5:18   ` [PATCH 2/3] lib: vsprintf: optimised put_dec() for 32-bit machines Denys Vlasenko
2010-08-06  7:08     ` Michal Nazarewicz
2010-08-06  7:35       ` Denys Vlasenko
2010-08-06  8:54         ` Michał Nazarewicz
2010-08-06  3:58 ` [PATCH 1/3] lib: vsprintf: optimised put_dec_trunc() and put_dec_full() Denys Vlasenko
2010-08-06  6:56   ` Michal Nazarewicz

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