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Re: [PATCH] i386: Assembly Implementation cleanup
- From: Torvald Riegel <triegel at redhat dot com>
- To: "H.J. Lu" <hjl dot tools at gmail dot com>
- Cc: Adhemerval Zanella <adhemerval dot zanella at linaro dot org>, GNU C Library <libc-alpha at sourceware dot org>
- Date: Wed, 12 Aug 2015 15:07:21 +0200
- 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>
On Tue, 2015-08-11 at 17:22 -0700, 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.
Does this matter for any of those functions? Are they typically called
on fast paths that would notice that? If not, I think ease of
maintenance is more worthwile.