From: Keir Fraser <keir.fraser@citrix.com>
Date: Wed, 16 Apr 2008 09:07:49 +0000 (+0100)
Subject: ioemu: drop reschedule of handle_buffered_io on I/O reqs
X-Git-Tag: 3.3.0-rc1~240^2~50
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=426747a871e69c0f789bbb03de7156170c120686;p=xen.git

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@eu.citrix.com>
---

diff --git a/tools/ioemu/target-i386-dm/helper2.c b/tools/ioemu/target-i386-dm/helper2.c
index 46fe5433a1..16623e90b3 100644
--- a/tools/ioemu/target-i386-dm/helper2.c
+++ b/tools/ioemu/target-i386-dm/helper2.c
@@ -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);