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Message-Id: <1372908771-33260-1-git-send-email-Waiman.Long@hp.com> Date: Wed, 3 Jul 2013 23:32:48 -0400 From: Waiman Long <Waiman.Long@...com> To: Alexander Viro <viro@...iv.linux.org.uk>, Jeff Layton <jlayton@...hat.com>, Miklos Szeredi <mszeredi@...e.cz>, Ingo Molnar <mingo@...hat.com>, Thomas Gleixner <tglx@...utronix.de> Cc: Waiman Long <Waiman.Long@...com>, linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org, Peter Zijlstra <peterz@...radead.org>, Steven Rostedt <rostedt@...dmis.org>, Linus Torvalds <torvalds@...ux-foundation.org>, Benjamin Herrenschmidt <benh@...nel.crashing.org>, Andi Kleen <andi@...stfloor.org>, "Chandramouleeswaran, Aswin" <aswin@...com>, "Norton, Scott J" <scott.norton@...com> Subject: [PATCH v4 00/12] Lockless update of reference count protected by spinlock v3->v4: - Replace helper function access to d_lock and d_count by using macros to redefine the old d_lock name to the spinlock and new d_refcount name to the reference count. This greatly reduces the size of this patchset from 25 to 12 and make it easier to review. v2->v3: - Completely revamp the packaging by adding a new lockref data structure that combines the spinlock with the reference count. Helper functions are also added to manipulate the new data structure. That results in modifying over 50 files, but the changes were trivial in most of them. - Change initial spinlock wait to use a timeout. - Force 64-bit alignment of the spinlock & reference count structure. - Add a new way to use the combo by using a new union and helper functions. v1->v2: - Add one more layer of indirection to LOCK_WITH_REFCOUNT macro. - Add __LINUX_SPINLOCK_REFCOUNT_H protection to spinlock_refcount.h. - Add some generic get/put macros into spinlock_refcount.h. This patchset supports a generic mechanism to atomically update a reference count that is protected by a spinlock without actually acquiring the lock itself. If the update doesn't succeeed, the caller will have to acquire the lock and update the reference count in the the old way. This will help in situation where there is a lot of spinlock contention because of frequent reference count update. The d_lock and d_count fields of the struct dentry in dcache.h was modified to use the new lockref data structure and the d_lock name is now a macro to the actual spinlock. The d_count name, however, cannot be reused as it has collision elsewhere in the kernel. So a new d_refcount name is now used for the reference count. This patch set causes significant performance improvement in the short workload of the AIM7 benchmark on a 8-socket x86-64 machine with 80 cores. patch 1: Introduce the new lockref data structure patch 2: Enable x86 architecture to use the feature patches 3-11: Rename all the d_count references to d_refcount patch 12: Change the dentry structure to use the lockref structure to improve performance for high contention cases Thank to Thomas Gleixner, Andi Kleen and Linus for their valuable input in shaping this patchset. Signed-off-by: Waiman Long <Waiman.Long@...com> Waiman Long (12): spinlock: A new lockref structure for lockless update of refcount spinlock: Enable x86 architecture to do lockless refcount update dcache: rename d_count field of dentry to d_refcount auto-fs: rename d_count field of dentry to d_refcount ceph-fs: rename d_count field of dentry to d_refcount coda-fs: rename d_count field of dentry to d_refcount config-fs: rename d_count field of dentry to d_refcount ecrypt-fs: rename d_count field of dentry to d_refcount file locking: rename d_count field of dentry to d_refcount nfs: rename d_count field of dentry to d_refcount nilfs2: rename d_count field of dentry to d_refcount dcache: Enable lockless update of refcount in dentry structure arch/x86/Kconfig | 3 + arch/x86/include/asm/spinlock_refcount.h | 1 + fs/autofs4/expire.c | 8 +- fs/autofs4/root.c | 2 +- fs/ceph/inode.c | 4 +- fs/ceph/mds_client.c | 2 +- fs/coda/dir.c | 4 +- fs/configfs/dir.c | 2 +- fs/dcache.c | 72 +++++----- fs/ecryptfs/inode.c | 2 +- fs/locks.c | 2 +- fs/namei.c | 6 +- fs/nfs/dir.c | 8 +- fs/nfs/unlink.c | 2 +- fs/nilfs2/super.c | 2 +- include/asm-generic/spinlock_refcount.h | 46 ++++++ include/linux/dcache.h | 21 ++-- include/linux/spinlock_refcount.h | 107 ++++++++++++++ kernel/Kconfig.locks | 5 + lib/Makefile | 2 + lib/spinlock_refcount.c | 229 ++++++++++++++++++++++++++++++ 21 files changed, 466 insertions(+), 64 deletions(-) create mode 100644 arch/x86/include/asm/spinlock_refcount.h create mode 100644 include/asm-generic/spinlock_refcount.h create mode 100644 include/linux/spinlock_refcount.h create mode 100644 lib/spinlock_refcount.c -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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