Re: [PATCH net-next v7 8/9] xen-netback: Timeout packets in RX path
From: Ian Campbell <hidden>
Date: 2014-03-13 10:39:08
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On Thu, 2014-03-06 at 21:48 +0000, Zoltan Kiss wrote:
quoted hunk ↗ jump to hunk
@@ -557,12 +577,25 @@ void xenvif_disconnect(struct xenvif *vif) void xenvif_free(struct xenvif *vif) { int i, unmap_timeout = 0; + /* Here we want to avoid timeout messages if an skb can be legitimatly
"legitimately"
+ * stucked somewhere else. Realisticly this could be an another vif's
"stuck" and "Realistically"
+ * internal or QDisc queue. That another vif also has this + * rx_drain_timeout_msecs timeout, but the timer only ditches the + * internal queue. After that, the QDisc queue can put in worst case + * XEN_NETIF_RX_RING_SIZE / MAX_SKB_FRAGS skbs into that another vif's + * internal queue, so we need several rounds of such timeouts until we + * can be sure that no another vif should have skb's from us. We are + * not sending more skb's, so newly stucked packets are not interesting
"stuck" again.
quoted hunk ↗ jump to hunk
diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c index 560950e..bb65c7c 100644 --- a/drivers/net/xen-netback/netback.c +++ b/drivers/net/xen-netback/netback.c@@ -63,6 +63,13 @@ module_param(separate_tx_rx_irq, bool, 0644); static unsigned int fatal_skb_slots = FATAL_SKB_SLOTS_DEFAULT; module_param(fatal_skb_slots, uint, 0444); +/* When guest ring is filled up, qdisc queues the packets for us, but we have + * to timeout them, otherwise other guests' packets can get stucked there
"stuck" Ian.