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From: heiko.carstens@de.ibm.com (Heiko Carstens)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 1/5] all: s390: move wrapper infrastructure to generic headers
Date: Wed, 3 Feb 2016 09:01:59 +0100	[thread overview]
Message-ID: <20160203080159.GA3369@osiris> (raw)
In-Reply-To: <20160202204156.GA27290@yury-N73SV>

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?

  reply	other threads:[~2016-02-03  8:01 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-01-25 16:57 [PATCH 0/5] all: s390: make compat wrappers the generic solution Yury Norov
2016-01-25 16:57 ` [PATCH 1/5] all: s390: move wrapper infrastructure to generic headers Yury Norov
2016-01-25 18:10   ` kbuild test robot
2016-01-28 12:16   ` Heiko Carstens
2016-01-28 16:31     ` Yury Norov
2016-02-01 11:42       ` Yury Norov
2016-02-02  7:39         ` Heiko Carstens
2016-02-02 15:43           ` Yury Norov
2016-02-02 16:08             ` Heiko Carstens
2016-02-02 19:54               ` Heiko Carstens
2016-02-02 20:41                 ` Yury Norov
2016-02-03  8:01                   ` Heiko Carstens [this message]
2016-02-17  8:22                   ` Heiko Carstens
2016-02-17 13:57                     ` Yury Norov
2016-01-25 16:57 ` [PATCH 2/5] all: declare new wrappers Yury Norov
2016-01-25 16:57 ` [PATCH 3/5] all: s390: redefine wrappers in generic code Yury Norov
2016-01-25 16:57 ` [PATCH 4/5] all: wrap getdents64 syscall Yury Norov
2016-01-25 16:57 ` [PATCH 5/5] all: introduce COMPAT_WRAPPER option and enable it for s390 Yury Norov

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