From: Jan Kiszka <jan.kiszka@siemens.com>
Date: Fri, 21 Jan 2011 20:48:20 +0000 (+0100)
Subject: kvm: Do not use qemu_fair_mutex
X-Git-Tag: v0.14.0-rc0~14^2~2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b66042c722e4e7b2811a08873b1ecf2c2c1e5f0a;p=thirdparty%2Fqemu.git

kvm: Do not use qemu_fair_mutex

The imbalance in the hold time of qemu_global_mutex only exists in TCG
mode. In contrast to TCG VCPUs, KVM drops the global lock during guest
execution. We already avoid touching the fairness lock from the
IO-thread in KVM mode, so also stop using it from the VCPU threads.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
---

diff --git a/cpus.c b/cpus.c
index 0309189bfd6..4c9928e2ce6 100644
--- a/cpus.c
+++ b/cpus.c
@@ -735,9 +735,7 @@ static sigset_t block_io_signals(void)
 void qemu_mutex_lock_iothread(void)
 {
     if (kvm_enabled()) {
-        qemu_mutex_lock(&qemu_fair_mutex);
         qemu_mutex_lock(&qemu_global_mutex);
-        qemu_mutex_unlock(&qemu_fair_mutex);
     } else {
         qemu_mutex_lock(&qemu_fair_mutex);
         if (qemu_mutex_trylock(&qemu_global_mutex)) {