48 lines
1.7 KiB
Diff
48 lines
1.7 KiB
Diff
From 3b39fa3e031d5b8a89c05302f3d73e7d4748bf58 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 13:37:00 +0100
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Subject: [PATCH 23/31] hw/net/xgamc: 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: [22/30] d83a91284970ced6f60964ded15d04405845e8bb
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The 'xgmac_enet_send' method has a 8k byte array used for copying
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data between guest and host. Skip the automatic zero-init of this
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array to eliminate the performance overhead in the I/O hot path.
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The 'frame' buffer will be fully initialized when reading guest
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memory to fetch the data to send.
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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: 20250610123709.835102-23-berrange@redhat.com
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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(cherry picked from commit 8b723287b84a62bb5d1a7799ef0959ca8e6c293a)
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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---
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hw/net/xgmac.c | 2 +-
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1 file changed, 1 insertion(+), 1 deletion(-)
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diff --git a/hw/net/xgmac.c b/hw/net/xgmac.c
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index ffe3fc8dbe..eff8022aca 100644
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--- a/hw/net/xgmac.c
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+++ b/hw/net/xgmac.c
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@@ -207,7 +207,7 @@ static void xgmac_enet_send(XgmacState *s)
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struct desc bd;
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int frame_size;
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int len;
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- uint8_t frame[8192];
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+ QEMU_UNINITIALIZED uint8_t frame[8192];
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uint8_t *ptr;
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ptr = frame;
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--
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2.39.3
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