From 51a2219bdceed16e81c6e2e2f08aed39c579728f Mon Sep 17 00:00:00 2001 From: Peter Lieven Date: Tue, 2 Dec 2014 12:05:50 +0100 Subject: [PATCH] coroutine: try harder not to delete coroutines 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 Reviewed-by: Fam Zheng Message-id: 1417518350-6167-8-git-send-email-pbonzini@redhat.com Signed-off-by: Stefan Hajnoczi --- qemu-coroutine.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/qemu-coroutine.c b/qemu-coroutine.c index da1b9615d0..525247b050 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);