From: Will Deacon <will.deacon@arm.com> To: linux-kernel@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org, peterz@infradead.org, mingo@kernel.org, boqun.feng@gmail.com, paulmck@linux.vnet.ibm.com, catalin.marinas@arm.com, Will Deacon <will.deacon@arm.com> Subject: [PATCH 00/10] kernel/locking: qspinlock improvements Date: Thu, 5 Apr 2018 17:58:57 +0100 [thread overview] Message-ID: <1522947547-24081-1-git-send-email-will.deacon@arm.com> (raw) Hi all, I've been kicking the tyres further on qspinlock and with this set of patches I'm happy with the performance and fairness properties. In particular, the locking algorithm now guarantees forward progress whereas the implementation in mainline can starve threads indefinitely in cmpxchg loops. Catalin has also implemented a model of this using TLA to prove that the lock is fair, although this doesn't take the memory model into account: https://git.kernel.org/pub/scm/linux/kernel/git/cmarinas/kernel-tla.git/commit/ I'd still like to get more benchmark numbers and wider exposure before enabling this for arm64, but my current testing is looking very promising. This series, along with the arm64-specific patches, is available at: https://git.kernel.org/pub/scm/linux/kernel/git/will/linux.git/log/?h=qspinlock Cheers, Will --->8 Jason Low (1): locking/mcs: Use smp_cond_load_acquire() in mcs spin loop Will Deacon (9): locking/qspinlock: Don't spin on pending->locked transition in slowpath locking/qspinlock: Remove unbounded cmpxchg loop from locking slowpath locking/qspinlock: Kill cmpxchg loop when claiming lock from head of queue locking/qspinlock: Use atomic_cond_read_acquire barriers: Introduce smp_cond_load_relaxed and atomic_cond_read_relaxed locking/qspinlock: Use smp_cond_load_relaxed to wait for next node locking/qspinlock: Merge struct __qspinlock into struct qspinlock locking/qspinlock: Make queued_spin_unlock use smp_store_release locking/qspinlock: Elide back-to-back RELEASE operations with smp_wmb() arch/x86/include/asm/qspinlock.h | 19 ++- arch/x86/include/asm/qspinlock_paravirt.h | 3 +- include/asm-generic/barrier.h | 27 ++++- include/asm-generic/qspinlock.h | 2 +- include/asm-generic/qspinlock_types.h | 32 ++++- include/linux/atomic.h | 2 + kernel/locking/mcs_spinlock.h | 10 +- kernel/locking/qspinlock.c | 191 ++++++++++-------------------- kernel/locking/qspinlock_paravirt.h | 34 ++---- 9 files changed, 141 insertions(+), 179 deletions(-) -- 2.1.4
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From: will.deacon@arm.com (Will Deacon) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH 00/10] kernel/locking: qspinlock improvements Date: Thu, 5 Apr 2018 17:58:57 +0100 [thread overview] Message-ID: <1522947547-24081-1-git-send-email-will.deacon@arm.com> (raw) Hi all, I've been kicking the tyres further on qspinlock and with this set of patches I'm happy with the performance and fairness properties. In particular, the locking algorithm now guarantees forward progress whereas the implementation in mainline can starve threads indefinitely in cmpxchg loops. Catalin has also implemented a model of this using TLA to prove that the lock is fair, although this doesn't take the memory model into account: https://git.kernel.org/pub/scm/linux/kernel/git/cmarinas/kernel-tla.git/commit/ I'd still like to get more benchmark numbers and wider exposure before enabling this for arm64, but my current testing is looking very promising. This series, along with the arm64-specific patches, is available at: https://git.kernel.org/pub/scm/linux/kernel/git/will/linux.git/log/?h=qspinlock Cheers, Will --->8 Jason Low (1): locking/mcs: Use smp_cond_load_acquire() in mcs spin loop Will Deacon (9): locking/qspinlock: Don't spin on pending->locked transition in slowpath locking/qspinlock: Remove unbounded cmpxchg loop from locking slowpath locking/qspinlock: Kill cmpxchg loop when claiming lock from head of queue locking/qspinlock: Use atomic_cond_read_acquire barriers: Introduce smp_cond_load_relaxed and atomic_cond_read_relaxed locking/qspinlock: Use smp_cond_load_relaxed to wait for next node locking/qspinlock: Merge struct __qspinlock into struct qspinlock locking/qspinlock: Make queued_spin_unlock use smp_store_release locking/qspinlock: Elide back-to-back RELEASE operations with smp_wmb() arch/x86/include/asm/qspinlock.h | 19 ++- arch/x86/include/asm/qspinlock_paravirt.h | 3 +- include/asm-generic/barrier.h | 27 ++++- include/asm-generic/qspinlock.h | 2 +- include/asm-generic/qspinlock_types.h | 32 ++++- include/linux/atomic.h | 2 + kernel/locking/mcs_spinlock.h | 10 +- kernel/locking/qspinlock.c | 191 ++++++++++-------------------- kernel/locking/qspinlock_paravirt.h | 34 ++---- 9 files changed, 141 insertions(+), 179 deletions(-) -- 2.1.4
next reply other threads:[~2018-04-05 16:58 UTC|newest] Thread overview: 94+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-04-05 16:58 Will Deacon [this message] 2018-04-05 16:58 ` [PATCH 00/10] kernel/locking: qspinlock improvements Will Deacon 2018-04-05 16:58 ` [PATCH 01/10] locking/qspinlock: Don't spin on pending->locked transition in slowpath Will Deacon 2018-04-05 16:58 ` Will Deacon 2018-04-05 16:58 ` [PATCH 02/10] locking/qspinlock: Remove unbounded cmpxchg loop from locking slowpath Will Deacon 2018-04-05 16:58 ` Will Deacon 2018-04-05 17:07 ` Peter Zijlstra 2018-04-05 17:07 ` Peter Zijlstra 2018-04-06 15:08 ` Will Deacon 2018-04-06 15:08 ` Will Deacon 2018-04-05 17:13 ` Peter Zijlstra 2018-04-05 17:13 ` Peter Zijlstra 2018-04-05 21:16 ` Waiman Long 2018-04-05 21:16 ` Waiman Long 2018-04-06 15:08 ` Will Deacon 2018-04-06 15:08 ` Will Deacon 2018-04-06 20:50 ` Waiman Long 2018-04-06 20:50 ` Waiman Long 2018-04-06 21:09 ` Paul E. McKenney 2018-04-06 21:09 ` Paul E. McKenney 2018-04-07 8:47 ` Peter Zijlstra 2018-04-07 8:47 ` Peter Zijlstra 2018-04-07 23:37 ` Paul E. McKenney 2018-04-07 23:37 ` Paul E. McKenney 2018-04-09 10:58 ` Will Deacon 2018-04-09 10:58 ` Will Deacon 2018-04-07 9:07 ` Peter Zijlstra 2018-04-07 9:07 ` Peter Zijlstra 2018-04-09 10:58 ` Will Deacon 2018-04-09 10:58 ` Will Deacon 2018-04-09 14:54 ` Will Deacon 2018-04-09 14:54 ` Will Deacon 2018-04-09 15:54 ` Peter Zijlstra 2018-04-09 15:54 ` Peter Zijlstra 2018-04-09 17:19 ` Will Deacon 2018-04-09 17:19 ` Will Deacon 2018-04-10 9:35 ` Peter Zijlstra 2018-04-10 9:35 ` Peter Zijlstra 2018-09-20 16:08 ` Peter Zijlstra 2018-09-20 16:08 ` Peter Zijlstra 2018-09-20 16:22 ` Peter Zijlstra 2018-09-20 16:22 ` Peter Zijlstra 2018-04-09 19:33 ` Waiman Long 2018-04-09 19:33 ` Waiman Long 2018-04-09 17:55 ` Waiman Long 2018-04-09 17:55 ` Waiman Long 2018-04-10 13:49 ` Sasha Levin 2018-04-10 13:49 ` Sasha Levin 2018-04-05 16:59 ` [PATCH 03/10] locking/qspinlock: Kill cmpxchg loop when claiming lock from head of queue Will Deacon 2018-04-05 16:59 ` Will Deacon 2018-04-05 17:19 ` Peter Zijlstra 2018-04-05 17:19 ` Peter Zijlstra 2018-04-06 10:54 ` Will Deacon 2018-04-06 10:54 ` Will Deacon 2018-04-05 16:59 ` [PATCH 04/10] locking/qspinlock: Use atomic_cond_read_acquire Will Deacon 2018-04-05 16:59 ` Will Deacon 2018-04-05 16:59 ` [PATCH 05/10] locking/mcs: Use smp_cond_load_acquire() in mcs spin loop Will Deacon 2018-04-05 16:59 ` Will Deacon 2018-04-05 16:59 ` [PATCH 06/10] barriers: Introduce smp_cond_load_relaxed and atomic_cond_read_relaxed Will Deacon 2018-04-05 16:59 ` Will Deacon 2018-04-05 17:22 ` Peter Zijlstra 2018-04-05 17:22 ` Peter Zijlstra 2018-04-06 10:55 ` Will Deacon 2018-04-06 10:55 ` Will Deacon 2018-04-05 16:59 ` [PATCH 07/10] locking/qspinlock: Use smp_cond_load_relaxed to wait for next node Will Deacon 2018-04-05 16:59 ` Will Deacon 2018-04-05 16:59 ` [PATCH 08/10] locking/qspinlock: Merge struct __qspinlock into struct qspinlock Will Deacon 2018-04-05 16:59 ` Will Deacon 2018-04-07 5:23 ` Boqun Feng 2018-04-07 5:23 ` Boqun Feng 2018-04-05 16:59 ` [PATCH 09/10] locking/qspinlock: Make queued_spin_unlock use smp_store_release Will Deacon 2018-04-05 16:59 ` Will Deacon 2018-04-05 16:59 ` [PATCH 10/10] locking/qspinlock: Elide back-to-back RELEASE operations with smp_wmb() Will Deacon 2018-04-05 16:59 ` Will Deacon 2018-04-05 17:28 ` Peter Zijlstra 2018-04-05 17:28 ` Peter Zijlstra 2018-04-06 11:34 ` Will Deacon 2018-04-06 11:34 ` Will Deacon 2018-04-06 13:05 ` Andrea Parri 2018-04-06 13:05 ` Andrea Parri 2018-04-06 15:27 ` Will Deacon 2018-04-06 15:27 ` Will Deacon 2018-04-06 15:49 ` Andrea Parri 2018-04-06 15:49 ` Andrea Parri 2018-04-07 5:47 ` Boqun Feng 2018-04-07 5:47 ` Boqun Feng 2018-04-09 10:47 ` Will Deacon 2018-04-09 10:47 ` Will Deacon 2018-04-06 13:22 ` [PATCH 00/10] kernel/locking: qspinlock improvements Andrea Parri 2018-04-06 13:22 ` Andrea Parri 2018-04-11 10:20 ` Catalin Marinas 2018-04-11 10:20 ` Catalin Marinas 2018-04-11 15:39 ` Andrea Parri 2018-04-11 15:39 ` Andrea Parri
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