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[Xen-changelog] [xen-unstable] ioemu: drop reschedule of handle_buffered

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Subject: [Xen-changelog] [xen-unstable] ioemu: drop reschedule of handle_buffered_io on I/O reqs
From: Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>
Date: Tue, 22 Apr 2008 07:10:17 -0700
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# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1208336869 -3600
# Node ID 774e38a40d012d3cc92715237d6932bcf01bbd39
# Parent  6cd0d4d1baa3ac9484733f2defa928d347fa6cc9
ioemu: drop reschedule of handle_buffered_io on I/O reqs

Rescheduling the call to handle_buffered_io costs the system call to
qemu_get_clock(), which is very expensive considering the the latency
we would like to achieve for I/O reqs, so we should avoid it.

That means that handle_buffered_io may be called as often as every
0.1s, but that's not so costly.

Signed-off-by: Samuel Thibault <samuel.thibault@xxxxxxxxxxxxx>
 tools/ioemu/target-i386-dm/helper2.c |    2 +-
 1 files changed, 1 insertion(+), 1 deletion(-)

diff -r 6cd0d4d1baa3 -r 774e38a40d01 tools/ioemu/target-i386-dm/helper2.c
--- a/tools/ioemu/target-i386-dm/helper2.c      Wed Apr 16 10:06:34 2008 +0100
+++ b/tools/ioemu/target-i386-dm/helper2.c      Wed Apr 16 10:07:49 2008 +0100
@@ -482,7 +482,7 @@ void cpu_handle_ioreq(void *opaque)
     CPUState *env = opaque;
     ioreq_t *req = cpu_get_ioreq();
-    handle_buffered_io(env);
+    __handle_buffered_iopage(env);
     if (req) {
         __handle_ioreq(env, req);

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