Re: [PATCH v4 0/4] mutex: Improve mutex performance by doing less atomic-ops & better spinning
* Waiman Long wrote: > v3->v4 > - Merge patch 4 into patch 2 > - Move patch 5 forward to become patch 1 > > v2->v3 > - Add patch 4 to remove new typedefs introduced in patch 2. > - Add patch 5 to remove SCHED_FEAT_OWNER_SPIN and move the mutex > spinning code to mutex.c. > > v1->v2 > - Remove the 2 mutex spinner patches and replaced it by another one >to improve the mutex spinning process. > - Remove changes made to kernel/mutex.h & localize changes in >kernel/mutex.c. > - Add an optional patch to remove architecture specific check in patch >1. The patches look pretty nice now - thanks Waiman. I have applied them to tip:core/locking and started testing them. Thanks, Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH v4 0/4] mutex: Improve mutex performance by doing less atomic-ops better spinning
* Waiman Long waiman.l...@hp.com wrote: v3-v4 - Merge patch 4 into patch 2 - Move patch 5 forward to become patch 1 v2-v3 - Add patch 4 to remove new typedefs introduced in patch 2. - Add patch 5 to remove SCHED_FEAT_OWNER_SPIN and move the mutex spinning code to mutex.c. v1-v2 - Remove the 2 mutex spinner patches and replaced it by another one to improve the mutex spinning process. - Remove changes made to kernel/mutex.h localize changes in kernel/mutex.c. - Add an optional patch to remove architecture specific check in patch 1. The patches look pretty nice now - thanks Waiman. I have applied them to tip:core/locking and started testing them. Thanks, Ingo -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH v4 0/4] mutex: Improve mutex performance by doing less atomic-ops & better spinning
v3->v4 - Merge patch 4 into patch 2 - Move patch 5 forward to become patch 1 v2->v3 - Add patch 4 to remove new typedefs introduced in patch 2. - Add patch 5 to remove SCHED_FEAT_OWNER_SPIN and move the mutex spinning code to mutex.c. v1->v2 - Remove the 2 mutex spinner patches and replaced it by another one to improve the mutex spinning process. - Remove changes made to kernel/mutex.h & localize changes in kernel/mutex.c. - Add an optional patch to remove architecture specific check in patch 1. This patch set is a collection of 4 different mutex related patches aimed at improving mutex performance especially for system with large number of CPUs. This is achieved by doing less atomic operations and better mutex spinning (when the CONFIG_MUTEX_SPIN_ON_OWNER is on). Patch 1 removes SCHED_FEAT_OWNER_SPIN which was just an earlier hack for testing purpose. It also moves the mutex spinning code back to mutex.c. Patch 2 reduces the number of atomic operations executed. It can produce dramatic performance improvement in the AIM7 benchmark with large number of CPUs. For example, there was a more than 3X improvement in the high_systime workload with a 3.7.10 kernel on an 8-socket x86-64 system with 80 cores. The 3.8 kernels, on the other hand, are not mutex limited for that workload anymore. So the performance improvement is only about 1% for the high_systime workload. Patch 3 improves the mutex spinning process by reducing contention among the spinners when competing for the mutex. This is done by using a MCS lock to put the spinners in a queue so that only the first spinner will try to acquire the mutex when it is available. This patch showed significant performance improvement of +30% on the AIM7 fserver and new_fserver workload. Compared with patches 2&3 in v1, the new patch 3 consistently provided better performance improvement at high user load (1100-2000) for the fserver and new_fserver AIM7 workloads. The old patches had around 10% and less improvement at high user load while the new patch produced 30% better performance for the same workloads. Patch 4 is an optional one for backing out architecture specific check in patch 2, if so desired. Waiman Long (4): mutex: Move mutex spinning code from sched/core.c back to mutex.c mutex: Make more scalable by doing less atomic operations mutex: Queue mutex spinners with MCS lock to reduce cacheline contention mutex: back out architecture specific check for negative mutex count include/linux/mutex.h |3 + include/linux/sched.h |1 - kernel/mutex.c | 151 +- kernel/sched/core.c | 45 -- kernel/sched/features.h |7 -- 5 files changed, 150 insertions(+), 57 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH v4 0/4] mutex: Improve mutex performance by doing less atomic-ops better spinning
v3-v4 - Merge patch 4 into patch 2 - Move patch 5 forward to become patch 1 v2-v3 - Add patch 4 to remove new typedefs introduced in patch 2. - Add patch 5 to remove SCHED_FEAT_OWNER_SPIN and move the mutex spinning code to mutex.c. v1-v2 - Remove the 2 mutex spinner patches and replaced it by another one to improve the mutex spinning process. - Remove changes made to kernel/mutex.h localize changes in kernel/mutex.c. - Add an optional patch to remove architecture specific check in patch 1. This patch set is a collection of 4 different mutex related patches aimed at improving mutex performance especially for system with large number of CPUs. This is achieved by doing less atomic operations and better mutex spinning (when the CONFIG_MUTEX_SPIN_ON_OWNER is on). Patch 1 removes SCHED_FEAT_OWNER_SPIN which was just an earlier hack for testing purpose. It also moves the mutex spinning code back to mutex.c. Patch 2 reduces the number of atomic operations executed. It can produce dramatic performance improvement in the AIM7 benchmark with large number of CPUs. For example, there was a more than 3X improvement in the high_systime workload with a 3.7.10 kernel on an 8-socket x86-64 system with 80 cores. The 3.8 kernels, on the other hand, are not mutex limited for that workload anymore. So the performance improvement is only about 1% for the high_systime workload. Patch 3 improves the mutex spinning process by reducing contention among the spinners when competing for the mutex. This is done by using a MCS lock to put the spinners in a queue so that only the first spinner will try to acquire the mutex when it is available. This patch showed significant performance improvement of +30% on the AIM7 fserver and new_fserver workload. Compared with patches 23 in v1, the new patch 3 consistently provided better performance improvement at high user load (1100-2000) for the fserver and new_fserver AIM7 workloads. The old patches had around 10% and less improvement at high user load while the new patch produced 30% better performance for the same workloads. Patch 4 is an optional one for backing out architecture specific check in patch 2, if so desired. Waiman Long (4): mutex: Move mutex spinning code from sched/core.c back to mutex.c mutex: Make more scalable by doing less atomic operations mutex: Queue mutex spinners with MCS lock to reduce cacheline contention mutex: back out architecture specific check for negative mutex count include/linux/mutex.h |3 + include/linux/sched.h |1 - kernel/mutex.c | 151 +- kernel/sched/core.c | 45 -- kernel/sched/features.h |7 -- 5 files changed, 150 insertions(+), 57 deletions(-) -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
