From: Heiko Carstens <heiko.carstens@de.ibm.com>
To: Yury Norov <ynorov@caviumnetworks.com>
Cc: linux-arch@vger.kernel.org, linux-s390@vger.kernel.org,
arnd@arndb.de, pinskia@gmail.com,
Prasun.Kapoor@caviumnetworks.com, catalin.marinas@arm.com,
Nathan_Lynch@mentor.com, linux-kernel@vger.kernel.org,
agraf@suse.de, klimov.linux@gmail.com, broonie@kernel.org,
joseph@codesourcery.com, schwidefsky@de.ibm.com,
linux-arm-kernel@lists.infradead.org,
christoph.muellner@theobroma-systems.com
Subject: Re: [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?
WARNING: multiple messages have this Message-ID (diff)
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?
next prev parent reply other threads:[~2016-02-03 8:02 UTC|newest]
Thread overview: 50+ 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 ` Yury Norov
2016-01-25 16:57 ` Yury Norov
2016-01-25 16:57 ` Yury Norov
2016-01-25 16:57 ` [PATCH 1/5] all: s390: move wrapper infrastructure to generic headers Yury Norov
2016-01-25 16:57 ` Yury Norov
2016-01-25 16:57 ` Yury Norov
2016-01-25 18:10 ` kbuild test robot
2016-01-25 18:10 ` kbuild test robot
2016-01-25 18:10 ` kbuild test robot
2016-01-25 18:10 ` kbuild test robot
2016-01-28 12:16 ` Heiko Carstens
2016-01-28 12:16 ` Heiko Carstens
2016-01-28 16:31 ` Yury Norov
2016-01-28 16:31 ` Yury Norov
2016-01-28 16:31 ` Yury Norov
2016-02-01 11:42 ` Yury Norov
2016-02-01 11:42 ` Yury Norov
2016-02-01 11:42 ` Yury Norov
2016-02-02 7:39 ` Heiko Carstens
2016-02-02 7:39 ` Heiko Carstens
2016-02-02 15:43 ` Yury Norov
2016-02-02 15:43 ` Yury Norov
2016-02-02 15:43 ` Yury Norov
2016-02-02 16:08 ` Heiko Carstens
2016-02-02 16:08 ` Heiko Carstens
2016-02-02 19:54 ` Heiko Carstens
2016-02-02 19:54 ` Heiko Carstens
2016-02-02 20:41 ` Yury Norov
2016-02-02 20:41 ` Yury Norov
2016-02-02 20:41 ` Yury Norov
2016-02-03 8:01 ` Heiko Carstens [this message]
2016-02-03 8:01 ` Heiko Carstens
2016-02-17 8:22 ` Heiko Carstens
2016-02-17 8:22 ` Heiko Carstens
2016-02-17 13:57 ` Yury Norov
2016-02-17 13:57 ` Yury Norov
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 ` Yury Norov
2016-01-25 16:57 ` Yury Norov
2016-01-25 16:57 ` [PATCH 3/5] all: s390: redefine wrappers in generic code Yury Norov
2016-01-25 16:57 ` Yury Norov
2016-01-25 16:57 ` Yury Norov
2016-01-25 16:57 ` [PATCH 4/5] all: wrap getdents64 syscall Yury Norov
2016-01-25 16:57 ` Yury Norov
2016-01-25 16:57 ` Yury Norov
2016-01-25 16:57 ` [PATCH 5/5] all: introduce COMPAT_WRAPPER option and enable it for s390 Yury Norov
2016-01-25 16:57 ` Yury Norov
2016-01-25 16:57 ` Yury Norov
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