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Re: [PATCH] i386: Assembly Implementation cleanup
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: Adhemerval Zanella <adhemerval dot zanella at linaro dot org>
- Cc: GNU C Library <libc-alpha at sourceware dot org>
- Date: Wed, 12 Aug 2015 05:44:34 -0700
- Subject: Re: [PATCH] i386: Assembly Implementation cleanup
- Authentication-results: sourceware.org; auth=none
- References: <5596AD3B dot 1060903 at linaro dot org> <CAMe9rOof5LzNfW_Yd2qgtX2=UMdP-E-ewdneJ9GjiCF9SPyNqQ at mail dot gmail dot com> <55CB3E37 dot 8080006 at linaro dot org>
On Wed, Aug 12, 2015 at 5:38 AM, Adhemerval Zanella
<adhemerval.zanella@linaro.org> wrote:
>
>
> On 11-08-2015 21:22, H.J. Lu wrote:
>> On Fri, Jul 3, 2015 at 8:41 AM, Adhemerval Zanella
>> <adhemerval.zanella@linaro.org> wrote:
>>> This patch removes i386 assembly implementation for epoll_wait, mmap,
>>> mmap64, semtimeop now that i386 have 6 argument syscall support from
>>> C code.
>>>
>>> The mmap implementation used is the wordsize-32 generic linux one.
>>>
>>> Tested in i386.
>>>
>>> ---
>>>
>>> * sysdeps/unix/sysv/linux/i386/mmap.c: New file.
>>> * sysdeps/unix/sysv/linux/i386/epoll_pwait.S: Remove file.
>>> * sysdeps/unix/sysv/linux/i386/mmap.S: Likewise.
>>> * sysdeps/unix/sysv/linux/i386/mmap64.S: Likewise.
>>> * sysdeps/unix/sysv/linux/i386/semtimedop.S: Likewise.
>>>
>>
>> What is the motivation? 6 argument syscalls aren't really inlined.
>> They put arguments on stack and call __libc_do_syscall. It is
>> slower than assembly code.
>>
>
> Same for ARM: code maintainability on functions that are not really
> performance-critical. This avoids issues like the x86 pthread_cond_*
> assembly implementation (which are now aimed to be removed), that
> required specific fixes just for x86.
Is there a way to truly inline syscall with 6 arguments, not by calling
__libc_do_syscall?
--
H.J.