From: Daniel P. Berrangé <berrange@redhat.com>
Date: Tue, 10 Jun 2025 12:36:41 +0000 (+0100)
Subject: block: skip automatic zero-init of large array in ioq_submit
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=83750c1da807c973b0b11d977d61df7e41122d03;p=thirdparty%2Fqemu.git

block: skip automatic zero-init of large array in ioq_submit

The 'ioq_submit' method has a struct array that is 8k in size.
Skip the automatic zero-init of this array to eliminate the
performance overhead in the I/O hot path.

The 'iocbs' array will selectively initialized when processing
the I/O data.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20250610123709.835102-4-berrange@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---

diff --git a/block/linux-aio.c b/block/linux-aio.c
index 407369f5c9..c200e7ad20 100644
--- a/block/linux-aio.c
+++ b/block/linux-aio.c
@@ -291,7 +291,7 @@ static void ioq_submit(LinuxAioState *s)
 {
     int ret, len;
     struct qemu_laiocb *aiocb;
-    struct iocb *iocbs[MAX_EVENTS];
+    QEMU_UNINITIALIZED struct iocb *iocbs[MAX_EVENTS];
     QSIMPLEQ_HEAD(, qemu_laiocb) completed;
 
     do {