* [PATCH] get 2% or more performance improved by reducing spin_lock race
@ 2013-06-07 7:31 Qinchuanyu
2013-06-07 8:50 ` Jason Wang
2013-06-07 12:36 ` Sergei Shtylyov
0 siblings, 2 replies; 3+ messages in thread
From: Qinchuanyu @ 2013-06-07 7:31 UTC (permalink / raw)
To: mst@redhat.com, Jason Wang
Cc: rusty@rustcorp.com.au, (kvm@vger.kernel.org),
(netdev@vger.kernel.org), Heguansen
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.
orignal 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 <qinchuanyu@huawei.com>
---
drivers/vhost/vhost.c | 5 +++--
1 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 94dbd25..8bee109 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -146,9 +146,10 @@ 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);
- }
- spin_unlock_irqrestore(&dev->work_lock, flags);
+ } else
+ spin_unlock_irqrestore(&dev->work_lock, flags);
}
void vhost_poll_queue(struct vhost_poll *poll)
--
1.7.3.1.msysgit.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] get 2% or more performance improved by reducing spin_lock race
2013-06-07 7:31 [PATCH] get 2% or more performance improved by reducing spin_lock race Qinchuanyu
@ 2013-06-07 8:50 ` Jason Wang
2013-06-07 12:36 ` Sergei Shtylyov
1 sibling, 0 replies; 3+ messages in thread
From: Jason Wang @ 2013-06-07 8:50 UTC (permalink / raw)
To: Qinchuanyu
Cc: mst@redhat.com, rusty@rustcorp.com.au, (kvm@vger.kernel.org),
(netdev@vger.kernel.org), Heguansen
On 06/07/2013 03:31 PM, Qinchuanyu wrote:
> 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.
> orignal 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 <qinchuanyu@huawei.com>
> ---
> drivers/vhost/vhost.c | 5 +++--
> 1 files changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> index 94dbd25..8bee109 100644
> --- a/drivers/vhost/vhost.c
> +++ b/drivers/vhost/vhost.c
> @@ -146,9 +146,10 @@ 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);
> - }
> - spin_unlock_irqrestore(&dev->work_lock, flags);
> + } else
> + spin_unlock_irqrestore(&dev->work_lock, flags);
> }
>
> void vhost_poll_queue(struct vhost_poll *poll)
Hi Chuanyu:
I believe you need a better name of the patch such as:
vhost: wake up worker outside spinlock
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] get 2% or more performance improved by reducing spin_lock race
2013-06-07 7:31 [PATCH] get 2% or more performance improved by reducing spin_lock race Qinchuanyu
2013-06-07 8:50 ` Jason Wang
@ 2013-06-07 12:36 ` Sergei Shtylyov
1 sibling, 0 replies; 3+ messages in thread
From: Sergei Shtylyov @ 2013-06-07 12:36 UTC (permalink / raw)
To: Qinchuanyu
Cc: mst@redhat.com, Jason Wang, rusty@rustcorp.com.au,
(kvm@vger.kernel.org), (netdev@vger.kernel.org), Heguansen
Hello.
On 07-06-2013 11:31, Qinchuanyu wrote:
> 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.
> orignal 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
Could you align your columns?
> Signed-off-by: Chuanyu Qin <qinchuanyu@huawei.com>
> ---
> drivers/vhost/vhost.c | 5 +++--
> 1 files changed, 3 insertions(+), 2 deletions(-)
> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> index 94dbd25..8bee109 100644
> --- a/drivers/vhost/vhost.c
> +++ b/drivers/vhost/vhost.c
> @@ -146,9 +146,10 @@ 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);
> - }
> - spin_unlock_irqrestore(&dev->work_lock, flags);
> + } else
> + spin_unlock_irqrestore(&dev->work_lock, flags);
You should have {} in the *else* branch, if you have it in the *if*
branch (and vice versa), according to Documentation/CodingStyle.
WBR, Sergei
^ permalink raw reply [flat|nested] 3+ messages in thread
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2013-06-07 8:50 ` Jason Wang
2013-06-07 12:36 ` Sergei Shtylyov
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