49 lines
1.8 KiB
Diff
49 lines
1.8 KiB
Diff
From 06915675e69c2ff0d1a686dcea200429f54fee74 Mon Sep 17 00:00:00 2001
|
|
From: =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= <berrange@redhat.com>
|
|
Date: Tue, 10 Jun 2025 13:36:50 +0100
|
|
Subject: [PATCH 13/31] hw/audio/sb16: skip automatic zero-init of large array
|
|
MIME-Version: 1.0
|
|
Content-Type: text/plain; charset=UTF-8
|
|
Content-Transfer-Encoding: 8bit
|
|
|
|
RH-Author: Stefan Hajnoczi <stefanha@redhat.com>
|
|
RH-MergeRequest: 461: Solve -ftrivial-auto-var-init performance regression with QEMU_UNINITIALIZED
|
|
RH-Jira: RHEL-99887
|
|
RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
|
|
RH-Commit: [12/30] 93e9b488f1ec99b425cc149c3aba8f824d000c73
|
|
|
|
The 'write_audio' method has a 4k byte array used for copying data
|
|
between the audio backend and device. Skip the automatic zero-init
|
|
of this array to eliminate the performance overhead in the I/O hot
|
|
path.
|
|
|
|
The 'tmpbuf' array will be fully initialized when reading data from
|
|
device memory.
|
|
|
|
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
|
|
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
|
|
Message-id: 20250610123709.835102-13-berrange@redhat.com
|
|
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
|
|
(cherry picked from commit 30c82f6657c1ee9fbb5473924b4d3273f214bd6f)
|
|
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
|
|
---
|
|
hw/audio/sb16.c | 2 +-
|
|
1 file changed, 1 insertion(+), 1 deletion(-)
|
|
|
|
diff --git a/hw/audio/sb16.c b/hw/audio/sb16.c
|
|
index fd76e78d18..04c818ed3d 100644
|
|
--- a/hw/audio/sb16.c
|
|
+++ b/hw/audio/sb16.c
|
|
@@ -1181,7 +1181,7 @@ static int write_audio (SB16State *s, int nchan, int dma_pos,
|
|
IsaDma *isa_dma = nchan == s->dma ? s->isa_dma : s->isa_hdma;
|
|
IsaDmaClass *k = ISADMA_GET_CLASS(isa_dma);
|
|
int temp, net;
|
|
- uint8_t tmpbuf[4096];
|
|
+ QEMU_UNINITIALIZED uint8_t tmpbuf[4096];
|
|
|
|
temp = len;
|
|
net = 0;
|
|
--
|
|
2.39.3
|
|
|