50 lines
1.8 KiB
Diff
50 lines
1.8 KiB
Diff
From 4b9a1a9154467fd65ac2a0a26959d3342d8fcd49 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 13:37:08 +0100
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Subject: [PATCH 55/57] net/socket: 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: 382: Solve -ftrivial-auto-var-init performance regression with QEMU_UNINITIALIZED
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RH-Jira: RHEL-99888
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RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
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RH-Commit: [29/30] 645ad4d138d1222ea9bd1b2ac3b84d9ff83e2fa2 (stefanha/centos-stream-qemu-kvm)
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The 'net_socket_send' method has a 68k 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 'buf1' array will be fully initialized when reading data off
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the network socket.
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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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Reviewed-by: Klaus Jensen <k.jensen@samsung.com>
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Reviewed-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
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Message-id: 20250610123709.835102-31-berrange@redhat.com
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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(cherry picked from commit 751b0e79f1e0e7f88fad2fe2f22595ad03d78859)
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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---
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net/socket.c | 2 +-
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1 file changed, 1 insertion(+), 1 deletion(-)
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diff --git a/net/socket.c b/net/socket.c
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index 8e3702e1f3..784dda686f 100644
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--- a/net/socket.c
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+++ b/net/socket.c
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@@ -157,7 +157,7 @@ static void net_socket_send(void *opaque)
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NetSocketState *s = opaque;
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int size;
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int ret;
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- uint8_t buf1[NET_BUFSIZE];
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+ QEMU_UNINITIALIZED uint8_t buf1[NET_BUFSIZE];
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const uint8_t *buf;
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size = recv(s->fd, buf1, sizeof(buf1), 0);
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--
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2.39.3
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