51 lines
1.8 KiB
Diff
51 lines
1.8 KiB
Diff
From 31886b02875b9d2d61710c14d6cdc0ab20d6dfc5 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 13:37:04 +0100
|
|
Subject: [PATCH 26/31] hw/usb/hcd-ohci: 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: [25/30] a69a9e0467a1b695b7fa07cdf30733b709867bd2
|
|
|
|
The 'ohci_service_iso_td' method has a 8k byte array used for copying
|
|
data between guest and host. Skip the automatic zero-init of this
|
|
array to eliminate the performance overhead in the I/O hot path.
|
|
|
|
The 'buf' array will be fully initialized when reading data from guest
|
|
memory.
|
|
|
|
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
|
|
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
|
|
Reviewed-by: Klaus Jensen <k.jensen@samsung.com>
|
|
Reviewed-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
|
|
Message-id: 20250610123709.835102-27-berrange@redhat.com
|
|
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
|
|
(cherry picked from commit 14997d521d1cd0bb36c902ef1032f0d3f2a3c912)
|
|
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
|
|
---
|
|
hw/usb/hcd-ohci.c | 2 +-
|
|
1 file changed, 1 insertion(+), 1 deletion(-)
|
|
|
|
diff --git a/hw/usb/hcd-ohci.c b/hw/usb/hcd-ohci.c
|
|
index 71b54914d3..72a9f9f474 100644
|
|
--- a/hw/usb/hcd-ohci.c
|
|
+++ b/hw/usb/hcd-ohci.c
|
|
@@ -577,7 +577,7 @@ static int ohci_service_iso_td(OHCIState *ohci, struct ohci_ed *ed)
|
|
USBDevice *dev;
|
|
USBEndpoint *ep;
|
|
USBPacket *pkt;
|
|
- uint8_t buf[8192];
|
|
+ QEMU_UNINITIALIZED uint8_t buf[8192];
|
|
bool int_req;
|
|
struct ohci_iso_td iso_td;
|
|
uint32_t addr;
|
|
--
|
|
2.39.3
|
|
|