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authorNeil Horman <nhorman@tuxdriver.com>2012-03-09 14:50:24 -0800
committerJames Bottomley <JBottomley@Parallels.com>2012-03-28 09:31:44 +0100
commit20dc3811a2adfac65d5974e3b022a85fdbb9e205 (patch)
treecfabd1f2ebe09711cb45f550d754cca7e125bd89 /drivers/scsi/fcoe
parentdd060e74fb4c2513420d8af7371cda2f3eea4fa9 (diff)
[SCSI] fcoe: reduce contention for fcoe_rx_list lock [v2]
There is potentially lots of contention for the rx_list_lock. On a cpu that is receiving lots of fcoe traffic, the softirq context has to add and release the lock for every frame it receives, as does the receiving per-cpu thread. We can reduce this contention somewhat by altering the per-cpu threads loop such that when traffic is detected on the fcoe_rx_list, we splice it to a temporary list. In this way, we can process multiple skbs while only having to acquire and release the fcoe_rx_list lock once. [ Braces around single statement while loop removed by Robert Love to satisfy checkpath.pl. ] Signed-off-by: Neil Horman <nhorman@tuxdriver.com> Acked-by: Vasu Dev <vasu.dev@intel.com> Signed-off-by: Robert Love <robert.w.love@intel.com> Signed-off-by: James Bottomley <JBottomley@Parallels.com>
Diffstat (limited to 'drivers/scsi/fcoe')
-rw-r--r--drivers/scsi/fcoe/fcoe.c22
1 files changed, 14 insertions, 8 deletions
diff --git a/drivers/scsi/fcoe/fcoe.c b/drivers/scsi/fcoe/fcoe.c
index d86ca37b3787..58c88b0e8792 100644
--- a/drivers/scsi/fcoe/fcoe.c
+++ b/drivers/scsi/fcoe/fcoe.c
@@ -1471,7 +1471,7 @@ static int fcoe_rcv(struct sk_buff *skb, struct net_device *netdev,
* in softirq context.
*/
__skb_queue_tail(&fps->fcoe_rx_list, skb);
- if (fps->fcoe_rx_list.qlen == 1)
+ if (fps->thread->state == TASK_INTERRUPTIBLE)
wake_up_process(fps->thread);
spin_unlock(&fps->fcoe_rx_list.lock);
@@ -1790,23 +1790,29 @@ static int fcoe_percpu_receive_thread(void *arg)
{
struct fcoe_percpu_s *p = arg;
struct sk_buff *skb;
+ struct sk_buff_head tmp;
+
+ skb_queue_head_init(&tmp);
set_user_nice(current, -20);
while (!kthread_should_stop()) {
spin_lock_bh(&p->fcoe_rx_list.lock);
- while ((skb = __skb_dequeue(&p->fcoe_rx_list)) == NULL) {
+ 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)) {
set_current_state(TASK_INTERRUPTIBLE);
spin_unlock_bh(&p->fcoe_rx_list.lock);
schedule();
set_current_state(TASK_RUNNING);
- if (kthread_should_stop())
- return 0;
- spin_lock_bh(&p->fcoe_rx_list.lock);
- }
- spin_unlock_bh(&p->fcoe_rx_list.lock);
- fcoe_recv_frame(skb);
+ } else
+ spin_unlock_bh(&p->fcoe_rx_list.lock);
}
return 0;
}