Re: [PATCH 1/5] all: s390: move wrapper infrastructure to generic headers

From	Heiko Carstens <heiko.carstens@de.ibm.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH 1/5] all: s390: move wrapper infrastructure to generic headers
Date	2016-02-03 09:10 +0100
Message-ID	<qY0FH-7K9-3@gated-at.bofh.it> (permalink)
References	(5 earlier) <qXDJ7-7w3-5@gated-at.bofh.it> <qXLnl-55B-29@gated-at.bofh.it> <qXLGH-5wZ-37@gated-at.bofh.it> <qXPhg-7Yl-15@gated-at.bofh.it> <qXQ3E-93-9@gated-at.bofh.it>
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On Tue, Feb 02, 2016 at 11:41:56PM +0300, Yury Norov wrote:
> On Tue, Feb 02, 2016 at 08:54:34PM +0100, Heiko Carstens wrote:
> > So I think I can summarize my point to: if you can enforce correctness, why
> > shouldn't you do it if the performance impact is only a single instruction.
> 
> For aarch64 it's 5 instructions. But what's more important (if ever),
> another wrapper takes another i-cache line...
>         <compat_SyS_ftruncate>:
>         stp     x29, x30, [sp,#-16]!
>         mov     x29, sp
>         bl      d40 <do_sys_ftruncate.constprop.3>
>         ldp     x29, x30, [sp],#16
>         ret

Why does gcc allocate a stackframe here? Don't you have tail call
optimization?

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Re: [PATCH 1/5] all: s390: move wrapper infrastructure to generic  headers Heiko Carstens <heiko.carstens@de.ibm.com> - 2016-01-28 13:20 +0100
  Re: [PATCH 1/5] all: s390: move wrapper infrastructure to generic  headers Yury Norov <ynorov@caviumnetworks.com> - 2016-01-28 17:40 +0100
    Re: [PATCH 1/5] all: s390: move wrapper infrastructure to generic  headers Yury Norov <ynorov@caviumnetworks.com> - 2016-02-01 12:50 +0100
      Re: [PATCH 1/5] all: s390: move wrapper infrastructure to generic  headers Heiko Carstens <heiko.carstens@de.ibm.com> - 2016-02-02 08:40 +0100
        Re: [PATCH 1/5] all: s390: move wrapper infrastructure to generic  headers Yury Norov <ynorov@caviumnetworks.com> - 2016-02-02 16:50 +0100
          Re: [PATCH 1/5] all: s390: move wrapper infrastructure to generic  headers Heiko Carstens <heiko.carstens@de.ibm.com> - 2016-02-02 17:10 +0100
            Re: [PATCH 1/5] all: s390: move wrapper infrastructure to generic  headers Heiko Carstens <heiko.carstens@de.ibm.com> - 2016-02-02 21:00 +0100
              Re: [PATCH 1/5] all: s390: move wrapper infrastructure to generic  headers Yury Norov <ynorov@caviumnetworks.com> - 2016-02-02 21:50 +0100
                Re: [PATCH 1/5] all: s390: move wrapper infrastructure to generic  headers Heiko Carstens <heiko.carstens@de.ibm.com> - 2016-02-03 09:10 +0100

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