From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37921) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XvlHq-0005tk-B5 for qemu-devel@nongnu.org; Tue, 02 Dec 2014 06:06:35 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XvlHi-0003mK-9v for qemu-devel@nongnu.org; Tue, 02 Dec 2014 06:06:30 -0500 Received: from mx1.redhat.com ([209.132.183.28]:53956) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XvlHi-0003m8-1c for qemu-devel@nongnu.org; Tue, 02 Dec 2014 06:06:22 -0500 From: Paolo Bonzini Date: Tue, 2 Dec 2014 12:05:50 +0100 Message-Id: <1417518350-6167-8-git-send-email-pbonzini@redhat.com> In-Reply-To: <1417518350-6167-1-git-send-email-pbonzini@redhat.com> References: <1417518350-6167-1-git-send-email-pbonzini@redhat.com> Subject: [Qemu-devel] [PATCH v2 7/7] coroutine: try harder not to delete coroutines List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: kwolf@redhat.com, ming.lei@canonical.com, pl@kamp.de, stefanha@redhat.com From: Peter Lieven Placing coroutines on the global pool should be preferrable, because it can help all threads. But if the global pool is full, we can still try to save some allocations by stashing completed coroutines on the local pool. This is quite cheap too, because it does not require atomic operations, and provides a gain of 15% in the best case. Signed-off-by: Peter Lieven Signed-off-by: Paolo Bonzini --- v1->v2: mention gain from this patch [Peter] change "alloc_pool_size +=" to "alloc_pool_size =" [Peter] qemu-coroutine.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/qemu-coroutine.c b/qemu-coroutine.c index da1b961..977f114 100644 --- a/qemu-coroutine.c +++ b/qemu-coroutine.c @@ -27,6 +27,7 @@ enum { static QSLIST_HEAD(, Coroutine) release_pool = QSLIST_HEAD_INITIALIZER(pool); static unsigned int release_pool_size; static __thread QSLIST_HEAD(, Coroutine) alloc_pool = QSLIST_HEAD_INITIALIZER(pool); +static __thread unsigned int alloc_pool_size; static __thread Notifier coroutine_pool_cleanup_notifier; static void coroutine_pool_cleanup(Notifier *n, void *value) @@ -58,13 +59,14 @@ Coroutine *qemu_coroutine_create(CoroutineEntry *entry) * release_pool_size and the actual size of release_pool. But * it is just a heuristic, it does not need to be perfect. */ - release_pool_size = 0; + alloc_pool_size = atomic_xchg(&release_pool_size, 0); QSLIST_MOVE_ATOMIC(&alloc_pool, &release_pool); co = QSLIST_FIRST(&alloc_pool); } } if (co) { QSLIST_REMOVE_HEAD(&alloc_pool, pool_next); + alloc_pool_size--; } } @@ -87,6 +89,11 @@ static void coroutine_delete(Coroutine *co) atomic_inc(&release_pool_size); return; } + if (alloc_pool_size < POOL_BATCH_SIZE) { + QSLIST_INSERT_HEAD(&alloc_pool, co, pool_next); + alloc_pool_size++; + return; + } } qemu_coroutine_delete(co); -- 2.1.0