the wake_up_process func is included by spin_lock/unlock in vhost_work_queue,
but it could be done outside the spin_lock.
I have test it with kernel 3.0.27 and guest suse11-sp2 using iperf,
the num as below.
                 original                 modified
thread_num  tp(Gbps)   vhost(%)  |  tp(Gbps)     vhost(%)
1           9.59        28.82    |   9.59        27.49
8           9.61        32.92    |   9.62        26.77
64          9.58        46.48    |   9.55        38.99
256         9.6         63.7     |   9.6         52.59

Signed-off-by: Chuanyu Qin <qinchua...@huawei.com>
---
 drivers/vhost/vhost.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 94dbd25..dcc7a17 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -146,9 +146,11 @@ static inline void vhost_work_queue(struct vhost_dev *dev,
        if (list_empty(&work->node)) {
                list_add_tail(&work->node, &dev->work_list);
                work->queue_seq++;
+               spin_unlock_irqrestore(&dev->work_lock, flags);
                wake_up_process(dev->worker);
+       } else {
+               spin_unlock_irqrestore(&dev->work_lock, flags);
        }
-       spin_unlock_irqrestore(&dev->work_lock, flags);
 }

 void vhost_poll_queue(struct vhost_poll *poll)
--
1.7.3.1.msysgit.0


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