From 1d5d48523900a4b0f25d6b52f1a93c84bd671186 Mon Sep 17 00:00:00 2001 From: David Vrabel Date: Tue, 8 Sep 2015 14:25:14 +0100 Subject: xen-netback: require fewer guest Rx slots when not using GSO Commit f48da8b14d04ca87ffcffe68829afd45f926ec6a (xen-netback: fix unlimited guest Rx internal queue and carrier flapping) introduced a regression. The PV frontend in IPXE only places 4 requests on the guest Rx ring. Since netback required at least (MAX_SKB_FRAGS + 1) slots, IPXE could not receive any packets. a) If GSO is not enabled on the VIF, fewer guest Rx slots are required for the largest possible packet. Calculate the required slots based on the maximum GSO size or the MTU. This calculation of the number of required slots relies on 1650d5455bd2 (xen-netback: always fully coalesce guest Rx packets) which present in 4.0-rc1 and later. b) Reduce the Rx stall detection to checking for at least one available Rx request. This is fine since we're predominately concerned with detecting interfaces which are down and thus have zero available Rx requests. Signed-off-by: David Vrabel Reviewed-by: Wei Liu Signed-off-by: David S. Miller --- drivers/net/xen-netback/netback.c | 23 ++++++++++++++++------- 1 file changed, 16 insertions(+), 7 deletions(-) (limited to 'drivers/net/xen-netback/netback.c') diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c index 42569b994ea8..b588b1a08cd4 100644 --- a/drivers/net/xen-netback/netback.c +++ b/drivers/net/xen-netback/netback.c @@ -149,9 +149,20 @@ static inline pending_ring_idx_t pending_index(unsigned i) return i & (MAX_PENDING_REQS-1); } -bool xenvif_rx_ring_slots_available(struct xenvif_queue *queue, int needed) +static int xenvif_rx_ring_slots_needed(struct xenvif *vif) +{ + if (vif->gso_mask) + return DIV_ROUND_UP(vif->dev->gso_max_size, PAGE_SIZE) + 1; + else + return DIV_ROUND_UP(vif->dev->mtu, PAGE_SIZE); +} + +static bool xenvif_rx_ring_slots_available(struct xenvif_queue *queue) { RING_IDX prod, cons; + int needed; + + needed = xenvif_rx_ring_slots_needed(queue->vif); do { prod = queue->rx.sring->req_prod; @@ -513,7 +524,7 @@ static void xenvif_rx_action(struct xenvif_queue *queue) skb_queue_head_init(&rxq); - while (xenvif_rx_ring_slots_available(queue, XEN_NETBK_RX_SLOTS_MAX) + while (xenvif_rx_ring_slots_available(queue) && (skb = xenvif_rx_dequeue(queue)) != NULL) { queue->last_rx_time = jiffies; @@ -1938,8 +1949,7 @@ static bool xenvif_rx_queue_stalled(struct xenvif_queue *queue) prod = queue->rx.sring->req_prod; cons = queue->rx.req_cons; - return !queue->stalled - && prod - cons < XEN_NETBK_RX_SLOTS_MAX + return !queue->stalled && prod - cons < 1 && time_after(jiffies, queue->last_rx_time + queue->vif->stall_timeout); } @@ -1951,14 +1961,13 @@ static bool xenvif_rx_queue_ready(struct xenvif_queue *queue) prod = queue->rx.sring->req_prod; cons = queue->rx.req_cons; - return queue->stalled - && prod - cons >= XEN_NETBK_RX_SLOTS_MAX; + return queue->stalled && prod - cons >= 1; } static bool xenvif_have_rx_work(struct xenvif_queue *queue) { return (!skb_queue_empty(&queue->rx_queue) - && xenvif_rx_ring_slots_available(queue, XEN_NETBK_RX_SLOTS_MAX)) + && xenvif_rx_ring_slots_available(queue)) || (queue->vif->stall_timeout && (xenvif_rx_queue_stalled(queue) || xenvif_rx_queue_ready(queue))) -- cgit v1.2.3 From 4c82ac3c37363e8c4ded6a5fe1ec5fa756b34df3 Mon Sep 17 00:00:00 2001 From: Wei Liu Date: Thu, 10 Sep 2015 11:18:57 +0100 Subject: xen-netback: respect user provided max_queues Originally that parameter was always reset to num_online_cpus during module initialisation, which renders it useless. The fix is to only set max_queues to num_online_cpus when user has not provided a value. Reported-by: Johnny Strom Signed-off-by: Wei Liu Reviewed-by: David Vrabel Acked-by: Ian Campbell Signed-off-by: David S. Miller --- drivers/net/xen-netback/netback.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'drivers/net/xen-netback/netback.c') diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c index b588b1a08cd4..abc1381264fc 100644 --- a/drivers/net/xen-netback/netback.c +++ b/drivers/net/xen-netback/netback.c @@ -2114,8 +2114,11 @@ static int __init netback_init(void) if (!xen_domain()) return -ENODEV; - /* Allow as many queues as there are CPUs, by default */ - xenvif_max_queues = num_online_cpus(); + /* Allow as many queues as there are CPUs if user has not + * specified a value. + */ + if (xenvif_max_queues == 0) + xenvif_max_queues = num_online_cpus(); if (fatal_skb_slots < XEN_NETBK_LEGACY_SLOTS_MAX) { pr_info("fatal_skb_slots too small (%d), bump it to XEN_NETBK_LEGACY_SLOTS_MAX (%d)\n", -- cgit v1.2.3