On Thu, 2012-06-21 at 15:24 -0400, Neil Horman wrote:
> Noticed that we can shuffle the code around in fcoe_percpu_receive_thread a
> bit
> and avoid taking the fcoe_rx_list lock twice per iteration. This should
> improve
> throughput somewhat. With this change we take the lock, and check for new
> frames in a single critical section. Only if the list is empty do we drop the
> lock and re-acquire it after being signaled to wake up.
>
> Change Notes:
> v2) did some further cleanup on the patch by replacing the 2nd call of
> spin_lock/splice_init with a goto to the top of the outer loop. This allows
> me
> to change the inner while loop to an if conditional and remove the sencond
> check
> of kthread_should_stop. Based on suggestion from Vasu Dev.
>
> Signed-off-by: Neil Horman <nhor...@tuxdriver.com>
> CC: Robert Love <robert.w.l...@intel.com>
> CC: Vasu Dev <vasu....@linux.intel.com>
> ---
> drivers/scsi/fcoe/fcoe.c | 18 ++++++++++--------
> 1 files changed, 10 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/scsi/fcoe/fcoe.c b/drivers/scsi/fcoe/fcoe.c
> index 0b48c7d..0d80837 100644
> --- a/drivers/scsi/fcoe/fcoe.c
> +++ b/drivers/scsi/fcoe/fcoe.c
> @@ -1816,23 +1816,25 @@ static int fcoe_percpu_receive_thread(void *arg)
>
> set_user_nice(current, -20);
>
> +retry:
> while (!kthread_should_stop()) {
>
> spin_lock_bh(&p->fcoe_rx_list.lock);
> skb_queue_splice_init(&p->fcoe_rx_list, &tmp);
> - spin_unlock_bh(&p->fcoe_rx_list.lock);
> -
> - while ((skb = __skb_dequeue(&tmp)) != NULL)
> - fcoe_recv_frame(skb);
>
> - spin_lock_bh(&p->fcoe_rx_list.lock);
> - if (!skb_queue_len(&p->fcoe_rx_list)) {
> + if (!skb_queue_len(&tmp)) {
> set_current_state(TASK_INTERRUPTIBLE);
> spin_unlock_bh(&p->fcoe_rx_list.lock);
> schedule();
> set_current_state(TASK_RUNNING);
> - } else
> - spin_unlock_bh(&p->fcoe_rx_list.lock);
> + goto retry;
> + }
> +
> + spin_unlock_bh(&p->fcoe_rx_list.lock);
> +
> + while ((skb = __skb_dequeue(&tmp)) != NULL)
> + fcoe_recv_frame(skb);
> +
> }
> return 0;
> }
Look good, Acked-by: Vasu Dev <vasu....@intel.com>
Thanks
Vasu
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