From: Will Deacon <will.deacon@arm.com>
To: Waiman Long <longman@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
linux-kernel@vger.kernel.org, linux-alpha@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-c6x-dev@linux-c6x.org,
uclinux-h8-devel@lists.sourceforge.jp,
linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org,
linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org,
nios2-dev@lists.rocketboards.org, openrisc@lists.librecores.org,
linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org,
linux-sh@vger.kernel.org, sparclinux@vger.kernel.org,
linux-um@lists.infradead.org, linux-xtensa@linux-xtensa.org,
linux-arch@vger.kernel.org, x86@kernel.org,
Arnd Bergmann <arnd@arndb.de>, Borislav Petkov <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>,
Davidlohr Bueso <dave@stgolabs.net>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Tim Chen <tim.c.chen@linux.intel.com>
Subject: Re: [PATCH v4 2/3] locking/rwsem: Remove rwsem-spinlock.c & use rwsem-xadd.c for all archs
Date: Wed, 20 Feb 2019 14:47:56 +0000 [thread overview]
Message-ID: <20190220144756.GK7523@fuggles.cambridge.arm.com> (raw)
In-Reply-To: <1550095217-12047-3-git-send-email-longman@redhat.com>
On Wed, Feb 13, 2019 at 05:00:16PM -0500, Waiman Long wrote:
> Currently, we have two different implementation of rwsem:
> 1) CONFIG_RWSEM_GENERIC_SPINLOCK (rwsem-spinlock.c)
> 2) CONFIG_RWSEM_XCHGADD_ALGORITHM (rwsem-xadd.c)
>
> As we are going to use a single generic implementation for rwsem-xadd.c
> and no architecture-specific code will be needed, there is no point
> in keeping two different implementations of rwsem. In most cases, the
> performance of rwsem-spinlock.c will be worse. It also doesn't get all
> the performance tuning and optimizations that had been implemented in
> rwsem-xadd.c over the years.
>
> For simplication, we are going to remove rwsem-spinlock.c and make all
> architectures use a single implementation of rwsem - rwsem-xadd.c.
>
> All references to RWSEM_GENERIC_SPINLOCK and RWSEM_XCHGADD_ALGORITHM
> in the code are removed.
>
> Suggested-by: Peter Zijlstra <peterz@infradead.org>
> Signed-off-by: Waiman Long <longman@redhat.com>
> ---
> arch/alpha/Kconfig | 7 -
> arch/arc/Kconfig | 3 -
> arch/arm/Kconfig | 4 -
> arch/arm64/Kconfig | 3 -
> arch/c6x/Kconfig | 3 -
> arch/csky/Kconfig | 3 -
> arch/h8300/Kconfig | 3 -
> arch/hexagon/Kconfig | 6 -
> arch/ia64/Kconfig | 4 -
> arch/m68k/Kconfig | 7 -
> arch/microblaze/Kconfig | 6 -
> arch/mips/Kconfig | 7 -
> arch/nds32/Kconfig | 3 -
> arch/nios2/Kconfig | 3 -
> arch/openrisc/Kconfig | 6 -
> arch/parisc/Kconfig | 6 -
> arch/powerpc/Kconfig | 7 -
> arch/riscv/Kconfig | 3 -
> arch/s390/Kconfig | 6 -
> arch/sh/Kconfig | 6 -
> arch/sparc/Kconfig | 8 -
> arch/unicore32/Kconfig | 6 -
> arch/x86/Kconfig | 3 -
> arch/x86/um/Kconfig | 6 -
> arch/xtensa/Kconfig | 3 -
> include/linux/rwsem-spinlock.h | 47 ------
> include/linux/rwsem.h | 5 -
> kernel/Kconfig.locks | 2 +-
> kernel/locking/Makefile | 4 +-
> kernel/locking/rwsem-spinlock.c | 339 ----------------------------------------
> kernel/locking/rwsem.h | 3 -
> 31 files changed, 2 insertions(+), 520 deletions(-)
> delete mode 100644 include/linux/rwsem-spinlock.h
> delete mode 100644 kernel/locking/rwsem-spinlock.c
Another nice cleanup, and it looks like the optimistic spinning in the xadd
implementation is predicated on ARCH_SUPPORTS_ATOMIC_RMW, so we're all good
there too.
Acked-by: Will Deacon <will.deacon@arm.com>
Will
next prev parent reply other threads:[~2019-02-20 14:48 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-13 22:00 [PATCH v4 0/3] locking/rwsem: Rwsem rearchitecture part 0 Waiman Long
2019-02-13 22:00 ` [PATCH v4 1/3] locking/rwsem: Remove arch specific rwsem files Waiman Long
2019-02-20 14:47 ` Will Deacon
2019-02-13 22:00 ` [PATCH v4 2/3] locking/rwsem: Remove rwsem-spinlock.c & use rwsem-xadd.c for all archs Waiman Long
2019-02-14 10:54 ` Geert Uytterhoeven
2019-02-14 11:12 ` Peter Zijlstra
2019-02-20 14:47 ` Will Deacon [this message]
2019-02-13 22:00 ` [PATCH v4 3/3] locking/rwsem: Optimize down_read_trylock() Waiman Long
2019-02-21 14:14 ` Will Deacon
2019-02-22 3:28 ` Waiman Long
2019-02-14 10:37 ` [PATCH v4 0/3] locking/rwsem: Rwsem rearchitecture part 0 Peter Zijlstra
2019-02-14 22:05 ` Waiman Long
2019-02-15 18:40 ` Will Deacon
2019-02-15 18:58 ` Waiman Long
2019-02-18 14:58 ` Will Deacon
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