From: Jason Wang <jasowang@redhat•com>
To: Qinchuanyu <qinchuanyu@huawei•com>
Cc: "mst@redhat•com" <mst@redhat•com>,
"rusty@rustcorp•com.au" <rusty@rustcorp•com.au>,
"(kvm@vger•kernel.org)" <kvm@vger•kernel.org>,
"(netdev@vger•kernel.org)" <netdev@vger•kernel.org>,
Heguansen <heguansen@huawei•com>
Subject: Re: [PATCH] get 2% or more performance improved by reducing spin_lock race
Date: Fri, 07 Jun 2013 16:50:35 +0800 [thread overview]
Message-ID: <51B19EDB.5040604@redhat.com> (raw)
In-Reply-To: <5872DA217C2FF7488B20897D84F904E7339109CE@nkgeml511-mbx.china.huawei.com>
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
next prev parent reply other threads:[~2013-06-07 8:51 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
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 [this message]
2013-06-07 12:36 ` Sergei Shtylyov
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