From: David Vrabel <david.vrabel@citrix.com>
To: <netdev@vger.kernel.org>
Cc: David Vrabel <david.vrabel@citrix.com>,
<xen-devel@lists.xenproject.org>,
Ian Campbell <ian.campbell@citrix.com>,
Wei Liu <wei.liu2@citrix.com>
Subject: [PATCHv1 net] xen-netback: notify immediately after pushing Tx response.
Date: Wed, 11 Mar 2015 15:27:59 +0000 [thread overview]
Message-ID: <1426087679-13927-1-git-send-email-david.vrabel@citrix.com> (raw)
This fixes a performance regression introduced by
7fbb9d8415d4a51cf542e87cf3a717a9f7e6aedc (xen-netback: release pending
index before pushing Tx responses)
Moving the notify outside of the spin locks means it can be delayed a
long time (if the dealloc thread is descheduled or there is an
interrupt or softirq).
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
---
drivers/net/xen-netback/netback.c | 23 ++++++++++++-----------
1 file changed, 12 insertions(+), 11 deletions(-)
diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index c4d68d7..7f8a466 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -96,6 +96,7 @@ static void xenvif_idx_release(struct xenvif_queue *queue, u16 pending_idx,
static void make_tx_response(struct xenvif_queue *queue,
struct xen_netif_tx_request *txp,
s8 st);
+static void push_tx_responses(struct xenvif_queue *queue);
static inline int tx_work_todo(struct xenvif_queue *queue);
@@ -655,15 +656,10 @@ static void xenvif_tx_err(struct xenvif_queue *queue,
unsigned long flags;
do {
- int notify;
-
spin_lock_irqsave(&queue->response_lock, flags);
make_tx_response(queue, txp, XEN_NETIF_RSP_ERROR);
- RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&queue->tx, notify);
+ push_tx_responses(queue);
spin_unlock_irqrestore(&queue->response_lock, flags);
- if (notify)
- notify_remote_via_irq(queue->tx_irq);
-
if (cons == end)
break;
txp = RING_GET_REQUEST(&queue->tx, cons++);
@@ -1655,7 +1651,6 @@ static void xenvif_idx_release(struct xenvif_queue *queue, u16 pending_idx,
{
struct pending_tx_info *pending_tx_info;
pending_ring_idx_t index;
- int notify;
unsigned long flags;
pending_tx_info = &queue->pending_tx_info[pending_idx];
@@ -1671,12 +1666,9 @@ static void xenvif_idx_release(struct xenvif_queue *queue, u16 pending_idx,
index = pending_index(queue->pending_prod++);
queue->pending_ring[index] = pending_idx;
- RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&queue->tx, notify);
+ push_tx_responses(queue);
spin_unlock_irqrestore(&queue->response_lock, flags);
-
- if (notify)
- notify_remote_via_irq(queue->tx_irq);
}
@@ -1697,6 +1689,15 @@ static void make_tx_response(struct xenvif_queue *queue,
queue->tx.rsp_prod_pvt = ++i;
}
+static void push_tx_responses(struct xenvif_queue *queue)
+{
+ int notify;
+
+ RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&queue->tx, notify);
+ if (notify)
+ notify_remote_via_irq(queue->tx_irq);
+}
+
static struct xen_netif_rx_response *make_rx_response(struct xenvif_queue *queue,
u16 id,
s8 st,
--
1.7.10.4
next reply other threads:[~2015-03-11 15:28 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-11 15:27 David Vrabel [this message]
2015-03-11 17:09 ` [Xen-devel] [PATCHv1 net] xen-netback: notify immediately after pushing Tx response Zoltan Kiss
2015-03-11 17:44 ` Wei Liu
2015-03-12 3:31 ` David Miller
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