From: Andrey Ryabinin <aryabinin@virtuozzo.com> To: Andrew Morton <akpm@linux-foundation.org> Cc: <linux-kernel@vger.kernel.org>, Andrey Ryabinin <aryabinin@virtuozzo.com>, <penguin-kernel@I-love.SAKURA.ne.jp>, <mhocko@kernel.org>, <linux-mm@kvack.org>, <hpa@zytor.com>, <chris@chris-wilson.co.uk>, <hch@lst.de>, <mingo@elte.hu>, <jszhang@marvell.com>, <joelaf@google.com>, <joaodias@google.com>, <willy@infradead.org>, <tglx@linutronix.de>, <thellstrom@vmware.com> Subject: [PATCH v2 5/5] mm/vmalloc: Don't spawn workers if somebody already purging Date: Wed, 12 Apr 2017 15:49:05 +0300 [thread overview] Message-ID: <20170412124905.25443-6-aryabinin@virtuozzo.com> (raw) In-Reply-To: <20170412124905.25443-1-aryabinin@virtuozzo.com> Don't schedule purge_vmap_work if mutex_is_locked(&vmap_purge_lock), as this means that purging is already running in another thread. There is no point to schedule extra purge_vmap_work if somebody is already purging for us, because that extra work will not do anything useful. To evaluate performance impact of this change test that calls fork() 100 000 times on the kernel with enabled CONFIG_VMAP_STACK=y and NR_CACHED_STACK changed to 0 (so that each fork()/exit() executes vmalloc()/vfree() call) was used. Commands: ~ # grep try_purge /proc/kallsyms ffffffff811d0dd0 t try_purge_vmap_area_lazy ~ # perf stat --repeat 10 -ae workqueue:workqueue_queue_work \ --filter 'function == 0xffffffff811d0dd0' ./fork gave me the following results: before: 30 workqueue:workqueue_queue_work ( +- 1.31% ) 1.613231060 seconds time elapsed ( +- 0.38% ) after: 15 workqueue:workqueue_queue_work ( +- 0.88% ) 1.615368474 seconds time elapsed ( +- 0.41% ) So there is no measurable difference on the performance of the test itself, but without the optimization we queue twice more jobs. This should save kworkers from doing some useless job. Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Suggested-by: Thomas Hellstrom <thellstrom@vmware.com> Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com> --- mm/vmalloc.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index ee62c0a..1079555 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -737,7 +737,8 @@ static void free_vmap_area_noflush(struct vmap_area *va) /* After this point, we may free va at any time */ llist_add(&va->purge_list, &vmap_purge_list); - if (unlikely(nr_lazy > lazy_max_pages())) + if (unlikely(nr_lazy > lazy_max_pages()) && + !mutex_is_locked(&vmap_purge_lock)) schedule_work(&purge_vmap_work); } -- 2.10.2
WARNING: multiple messages have this Message-ID (diff)
From: Andrey Ryabinin <aryabinin@virtuozzo.com> To: Andrew Morton <akpm@linux-foundation.org> Cc: linux-kernel@vger.kernel.org, Andrey Ryabinin <aryabinin@virtuozzo.com>, penguin-kernel@I-love.SAKURA.ne.jp, mhocko@kernel.org, linux-mm@kvack.org, hpa@zytor.com, chris@chris-wilson.co.uk, hch@lst.de, mingo@elte.hu, jszhang@marvell.com, joelaf@google.com, joaodias@google.com, willy@infradead.org, tglx@linutronix.de, thellstrom@vmware.com Subject: [PATCH v2 5/5] mm/vmalloc: Don't spawn workers if somebody already purging Date: Wed, 12 Apr 2017 15:49:05 +0300 [thread overview] Message-ID: <20170412124905.25443-6-aryabinin@virtuozzo.com> (raw) In-Reply-To: <20170412124905.25443-1-aryabinin@virtuozzo.com> Don't schedule purge_vmap_work if mutex_is_locked(&vmap_purge_lock), as this means that purging is already running in another thread. There is no point to schedule extra purge_vmap_work if somebody is already purging for us, because that extra work will not do anything useful. To evaluate performance impact of this change test that calls fork() 100 000 times on the kernel with enabled CONFIG_VMAP_STACK=y and NR_CACHED_STACK changed to 0 (so that each fork()/exit() executes vmalloc()/vfree() call) was used. Commands: ~ # grep try_purge /proc/kallsyms ffffffff811d0dd0 t try_purge_vmap_area_lazy ~ # perf stat --repeat 10 -ae workqueue:workqueue_queue_work \ --filter 'function == 0xffffffff811d0dd0' ./fork gave me the following results: before: 30 workqueue:workqueue_queue_work ( +- 1.31% ) 1.613231060 seconds time elapsed ( +- 0.38% ) after: 15 workqueue:workqueue_queue_work ( +- 0.88% ) 1.615368474 seconds time elapsed ( +- 0.41% ) So there is no measurable difference on the performance of the test itself, but without the optimization we queue twice more jobs. This should save kworkers from doing some useless job. Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Suggested-by: Thomas Hellstrom <thellstrom@vmware.com> Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com> --- mm/vmalloc.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index ee62c0a..1079555 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -737,7 +737,8 @@ static void free_vmap_area_noflush(struct vmap_area *va) /* After this point, we may free va at any time */ llist_add(&va->purge_list, &vmap_purge_list); - if (unlikely(nr_lazy > lazy_max_pages())) + if (unlikely(nr_lazy > lazy_max_pages()) && + !mutex_is_locked(&vmap_purge_lock)) schedule_work(&purge_vmap_work); } -- 2.10.2 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2017-04-12 12:49 UTC|newest] Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-03-30 10:27 [PATCH 1/4] mm/vmalloc: allow to call vfree() in atomic context Andrey Ryabinin 2017-03-30 10:27 ` Andrey Ryabinin 2017-03-30 10:27 ` Andrey Ryabinin 2017-03-30 10:27 ` [PATCH 2/4] x86/ldt: use vfree() instead of vfree_atomic() Andrey Ryabinin 2017-03-30 10:27 ` Andrey Ryabinin 2017-03-31 8:05 ` Thomas Gleixner 2017-03-31 8:05 ` Thomas Gleixner 2017-03-30 10:27 ` [PATCH 3/4] kernel/fork: use vfree() instead of vfree_atomic() to free thread stack Andrey Ryabinin 2017-03-30 10:27 ` Andrey Ryabinin 2017-03-30 10:27 ` [PATCH 4/4] mm/vmalloc: remove vfree_atomic() Andrey Ryabinin 2017-03-30 10:27 ` Andrey Ryabinin 2017-03-30 17:18 ` Matthew Wilcox 2017-03-30 17:18 ` Matthew Wilcox 2017-03-30 15:27 ` Andrey Ryabinin 2017-03-30 15:27 ` Andrey Ryabinin 2017-04-04 9:40 ` Michal Hocko 2017-04-04 9:40 ` Michal Hocko 2017-03-30 12:00 ` [PATCH 1/4] mm/vmalloc: allow to call vfree() in atomic context Thomas Hellstrom 2017-03-30 12:00 ` Thomas Hellstrom 2017-03-30 12:00 ` Thomas Hellstrom 2017-03-30 14:48 ` Andrey Ryabinin 2017-03-30 14:48 ` Andrey Ryabinin 2017-03-30 14:48 ` Andrey Ryabinin 2017-03-30 15:04 ` Thomas Hellstrom 2017-03-30 15:04 ` Thomas Hellstrom 2017-03-30 15:04 ` Thomas Hellstrom 2017-04-04 9:41 ` Michal Hocko 2017-04-04 9:41 ` Michal Hocko 2017-04-04 9:49 ` Thomas Hellstrom 2017-04-04 9:49 ` Thomas Hellstrom 2017-04-04 9:49 ` Thomas Hellstrom 2017-04-05 10:31 ` Andrey Ryabinin 2017-04-05 10:31 ` Andrey Ryabinin 2017-04-05 10:31 ` Andrey Ryabinin 2017-04-05 10:42 ` Michal Hocko 2017-04-05 10:42 ` Michal Hocko 2017-04-05 11:42 ` Vlastimil Babka 2017-04-05 11:42 ` Vlastimil Babka 2017-04-05 12:14 ` Michal Hocko 2017-04-05 12:14 ` Michal Hocko 2017-03-30 22:22 ` Andrew Morton 2017-03-30 22:22 ` Andrew Morton 2017-03-30 22:22 ` Andrew Morton 2017-03-31 7:12 ` Joel Fernandes 2017-03-31 7:12 ` Joel Fernandes 2017-03-31 9:26 ` Andrey Ryabinin 2017-03-31 9:26 ` Andrey Ryabinin 2017-03-31 9:26 ` Andrey Ryabinin 2017-04-04 9:36 ` Michal Hocko 2017-04-04 9:36 ` Michal Hocko 2017-04-04 9:38 ` Michal Hocko 2017-04-04 9:38 ` Michal Hocko 2017-04-12 12:49 ` [PATCH v2 0/5] " Andrey Ryabinin 2017-04-12 12:49 ` Andrey Ryabinin 2017-04-12 12:49 ` [PATCH v2 1/5] mm/vmalloc: " Andrey Ryabinin 2017-04-12 12:49 ` Andrey Ryabinin 2017-04-12 12:49 ` Andrey Ryabinin 2017-04-12 12:49 ` [PATCH v2 2/5] x86/ldt: use vfree() instead of vfree_atomic() Andrey Ryabinin 2017-04-12 12:49 ` Andrey Ryabinin 2017-04-12 12:49 ` [PATCH v2 3/5] kernel/fork: use vfree() instead of vfree_atomic() to free thread stack Andrey Ryabinin 2017-04-12 12:49 ` Andrey Ryabinin 2017-04-12 12:49 ` [PATCH v2 4/5] mm/vmalloc: remove vfree_atomic() Andrey Ryabinin 2017-04-12 12:49 ` Andrey Ryabinin 2017-04-12 12:49 ` Andrey Ryabinin [this message] 2017-04-12 12:49 ` [PATCH v2 5/5] mm/vmalloc: Don't spawn workers if somebody already purging Andrey Ryabinin
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