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From: Arnd Bergmann <arnd@arndb.de>
To: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Russell King <linux@armlinux.org.uk>,
	Ingo Molnar <mingo@redhat.com>, Waiman Long <longman@redhat.com>,
	Will Deacon <will@kernel.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH 6/6] ARM: Inline locking functions for !PREEMPTION
Date: Mon, 14 Oct 2019 12:01:02 +0200	[thread overview]
Message-ID: <CAK8P3a1Mu0Ghy1VtD7NBKQ4-ZMsYQe_bjYBAshRMTYTWtxzbPw@mail.gmail.com> (raw)
In-Reply-To: <CAK8P3a2hYteGizk=--_Z1kE200_ORL52QEK5RBTMtXt5_UzmhA@mail.gmail.com>

On Mon, Oct 14, 2019 at 9:43 AM Arnd Bergmann <arnd@arndb.de> wrote:
> On Mon, Oct 14, 2019 at 12:14 AM Sebastian Andrzej Siewior <sebastian@breakpoint.cc> wrote
>
> Also, the output of 'size vmlinux' before and after the patch for
> multi_v7_defconfig would be useful to have in the changelog, as there
> are a couple of platforms that are particularly sensitive to object code
> size changes.

To follow up, here are the numbers I get, building the linux-5.4-rc2
multi_v7_defconfig with clang-9, comparing the original spinlock
and the qspinlock, combined with inlining all locks or leaving them
out of line:

   text    data     bss     dec     hex filename
15294816 6958636 404480 22657932 159bb8c vmlinux-orig
16004898 6962060 404480 23371438 1649eae vmlinux-orig-inline
15198619 6958812 404560 22561991 15844c7 vmlinux-qlock-noinline
15622897 6962116 404560 22989573 15ecb05 vmlinux-qlock-inline

This gives us a 1.5% size increase over the original code with
inlining, or a 0.5% decrease without inlining, or about 1.9% size
difference for the Kconfig change itself, which does sound
significant.

Maybe it should be configurable?

      Arnd

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  reply	other threads:[~2019-10-14 10:01 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-13 22:13 [RFC PATCH 0/6 v2] Queued spinlocks/RW-locks for ARM Sebastian Andrzej Siewior
2019-10-13 22:13 ` [PATCH 1/6] sh: Move cmpxchg-xchg.h to asm-generic Sebastian Andrzej Siewior
2019-10-14  7:25   ` Arnd Bergmann
2019-10-15 22:31     ` [PATCH 1/6 v2] " Sebastian Andrzej Siewior
2019-10-13 22:13 ` [PATCH 2/6] ARM: cmpxchg: Define first cmpxchg() followed by xchg() Sebastian Andrzej Siewior
2019-10-13 22:13 ` [PATCH 3/6] ARM: Add xchg_{8|16}() on generic cmpxchg() on CPU_V6 Sebastian Andrzej Siewior
2019-10-13 22:13 ` [PATCH 4/6] ARM: Use qrwlock implementation Sebastian Andrzej Siewior
2019-10-13 22:13 ` [PATCH 5/6] ARM: Use qspinlock implementation Sebastian Andrzej Siewior
2019-10-13 22:13 ` [PATCH 6/6] ARM: Inline locking functions for !PREEMPTION Sebastian Andrzej Siewior
2019-10-14  7:43   ` Arnd Bergmann
2019-10-14 10:01     ` Arnd Bergmann [this message]
2019-10-15 22:30       ` Sebastian Andrzej Siewior
2019-10-15 22:37         ` Waiman Long
2019-10-15 22:47           ` Arnd Bergmann
2019-10-15 22:04     ` Sebastian Andrzej Siewior
2019-10-14  9:00 ` [RFC PATCH 0/6 v2] Queued spinlocks/RW-locks for ARM Arnd Bergmann
2019-10-16 15:57 ` Will Deacon
2019-10-16 17:45   ` Waiman Long
2019-10-16 18:33     ` Arnd Bergmann
2019-10-16 21:35     ` Sebastian Andrzej Siewior
2019-10-16 22:09   ` Sebastian Andrzej Siewior
2019-10-17 15:36     ` Waiman Long

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