49 lines
1.8 KiB
Diff
49 lines
1.8 KiB
Diff
From 6aac6e3888bd249856dc5bc91a40d9b4eb60f732 Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= <berrange@redhat.com>
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Date: Tue, 10 Jun 2025 13:36:48 +0100
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Subject: [PATCH 11/31] hw/audio/gus: skip automatic zero-init of large array
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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RH-Author: Stefan Hajnoczi <stefanha@redhat.com>
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RH-MergeRequest: 461: Solve -ftrivial-auto-var-init performance regression with QEMU_UNINITIALIZED
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RH-Jira: RHEL-99887
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RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
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RH-Commit: [10/30] 1af0f37dbbd3f3703988dfd6548e2ba018f05ee7
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The 'GUS_read_DMA' method has a 4k byte array used for copying
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data between the audio backend and device. Skip the automatic
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zero-init of this array to eliminate the performance overhead in
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the I/O hot path.
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The 'tmpbuf' array will be fully initialized when reading data
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from device memory.
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Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
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Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
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Message-id: 20250610123709.835102-11-berrange@redhat.com
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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(cherry picked from commit 2e438da4929018c62609381e1156aac0b2fe3de3)
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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---
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hw/audio/gus.c | 2 +-
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1 file changed, 1 insertion(+), 1 deletion(-)
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diff --git a/hw/audio/gus.c b/hw/audio/gus.c
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index 4beb3fd74e..e8b0b85d44 100644
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--- a/hw/audio/gus.c
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+++ b/hw/audio/gus.c
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@@ -183,7 +183,7 @@ static int GUS_read_DMA (void *opaque, int nchan, int dma_pos, int dma_len)
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{
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GUSState *s = opaque;
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IsaDmaClass *k = ISADMA_GET_CLASS(s->isa_dma);
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- char tmpbuf[4096];
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+ QEMU_UNINITIALIZED char tmpbuf[4096];
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int pos = dma_pos, mode, left = dma_len - dma_pos;
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ldebug ("read DMA %#x %d\n", dma_pos, dma_len);
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--
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2.39.3
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