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Commit c8a4d299 authored by David Vrabel's avatar David Vrabel Committed by David S. Miller
Browse files

xen-netback: notify immediately after pushing Tx response. 



This fixes a performance regression introduced by
7fbb9d84 (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: default avatarDavid Vrabel <david.vrabel@citrix.com>
Reviewed-by: default avatarZoltan Kiss <zoltan.kiss@linaro.org>
Acked-by: default avatarWei Liu <wei.liu2@citrix.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent b1cb59cf

drivers/net/xen-netback/netback.c

+12 −11
Original line number Diff line number Diff line
@@ -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++);
@@ -1657,7 +1653,6 @@ 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];
@@ -1673,12 +1668,9 @@ 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);

}
@@ -1699,6 +1691,15 @@ 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,