From mboxrd@z Thu Jan 1 00:00:00 1970 From: Will Deacon 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 Message-ID: <20190220144756.GK7523@fuggles.cambridge.arm.com> References: <1550095217-12047-1-git-send-email-longman@redhat.com> <1550095217-12047-3-git-send-email-longman@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1550095217-12047-3-git-send-email-longman@redhat.com> Sender: linux-kernel-owner@vger.kernel.org To: Waiman Long Cc: Peter Zijlstra , Ingo Molnar , Thomas Gleixner , 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 , Borislav List-Id: linux-arch.vger.kernel.org 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 > Signed-off-by: Waiman Long > --- > 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 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:59222 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726285AbfBTOsF (ORCPT ); Wed, 20 Feb 2019 09:48:05 -0500 Date: Wed, 20 Feb 2019 14:47:56 +0000 From: Will Deacon Subject: Re: [PATCH v4 2/3] locking/rwsem: Remove rwsem-spinlock.c & use rwsem-xadd.c for all archs Message-ID: <20190220144756.GK7523@fuggles.cambridge.arm.com> References: <1550095217-12047-1-git-send-email-longman@redhat.com> <1550095217-12047-3-git-send-email-longman@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1550095217-12047-3-git-send-email-longman@redhat.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Waiman Long Cc: Peter Zijlstra , Ingo Molnar , Thomas Gleixner , 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 , Borislav Petkov , "H. Peter Anvin" , Davidlohr Bueso , Linus Torvalds , Andrew Morton , Tim Chen Message-ID: <20190220144756.x2jekNfLK5HHDyhGl_exm98lm6bZgoUMb02rvn94M_Q@z> 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 > Signed-off-by: Waiman Long > --- > 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