[Qemu-devel] [PATCH 33/35] kvm: Do not use qemu_fair_mutex

[Marcelo Tosatti]

From: Jan Kiszka <address@hidden>

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 <address@hidden>
Signed-off-by: Marcelo Tosatti <address@hidden>
---
 cpus.c |    2 --
 1 files changed, 0 insertions(+), 2 deletions(-)

diff --git a/cpus.c b/cpus.c
index 0309189..4c9928e 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)) {
-- 
1.7.2.3