From: Yaowei Bai <baiyaowei@cmss.chinamobile.com>
Date: Wed, 14 Sep 2016 11:03:39 +0000 (-0400)
Subject: aio-posix: avoid unnecessary aio_epoll_enabled() calls
X-Git-Tag: v2.8.0-rc0~104^2~5
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=6b9424689a32bb76942ec39f6d5c60b72eb002e0;p=thirdparty%2Fqemu.git

aio-posix: avoid unnecessary aio_epoll_enabled() calls

As epoll whether enabled or not is a global setting, we can just
check it only once rather than checking it with every node iteration.
Through this we can avoid a lot of checks when epoll is not enabled.

Signed-off-by: Yaowei Bai <baiyaowei@cmss.chinamobile.com>
Reviewed-by: Xiubo Li <lixiubo@cmss.chinamobile.com>
Message-id: 1473851019-7005-3-git-send-email-baiyaowei@cmss.chinamobile.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---

diff --git a/aio-posix.c b/aio-posix.c
index 43162a9f291..4ef34dd1750 100644
--- a/aio-posix.c
+++ b/aio-posix.c
@@ -431,11 +431,13 @@ bool aio_poll(AioContext *ctx, bool blocking)
     assert(npfd == 0);
 
     /* fill pollfds */
-    QLIST_FOREACH(node, &ctx->aio_handlers, node) {
-        if (!node->deleted && node->pfd.events
-            && !aio_epoll_enabled(ctx)
-            && aio_node_check(ctx, node->is_external)) {
-            add_pollfd(node);
+
+    if (!aio_epoll_enabled(ctx)) {
+        QLIST_FOREACH(node, &ctx->aio_handlers, node) {
+            if (!node->deleted && node->pfd.events
+                && aio_node_check(ctx, node->is_external)) {
+                add_pollfd(node);
+            }
         }
     }