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authorEric Dumazet <edumazet@google.com>2016-11-23 08:44:56 -0800
committerDavid S. Miller <davem@davemloft.net>2016-11-25 19:37:49 -0500
commitf52dffe049ee11ecc02588a118fbe4092672fbaa (patch)
treea5532c4e1afd9e1a48a3c4a6f17f69af91344fe4 /net
parentca89fa77b4488ecf2e3f72096386e8f3a58fe2fc (diff)
net: properly flush delay-freed skbs
Typical NAPI drivers use napi_consume_skb(skb) at TX completion time. This put skb in a percpu special queue, napi_alloc_cache, to get bulk frees. It turns out the queue is not flushed and hits the NAPI_SKB_CACHE_SIZE limit quite often, with skbs that were queued hundreds of usec earlier. I measured this can take ~6000 nsec to perform one flush. __kfree_skb_flush() can be called from two points right now : 1) From net_tx_action(), but only for skbs that were queued to sd->completion_queue. -> Irrelevant for NAPI drivers in normal operation. 2) From net_rx_action(), but only under high stress or if RPS/RFS has a pending action. This patch changes net_rx_action() to perform the flush in all cases and after more urgent operations happened (like kicking remote CPUS for RPS/RFS). Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Jesper Dangaard Brouer <brouer@redhat.com> Cc: Alexander Duyck <alexander.h.duyck@intel.com> Acked-by: Alexander Duyck <alexander.h.duyck@intel.com> Acked-by: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/core/dev.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/net/core/dev.c b/net/core/dev.c
index f71b34ab57a5..048b46b7c92a 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -5260,7 +5260,7 @@ static __latent_entropy void net_rx_action(struct softirq_action *h)
if (list_empty(&list)) {
if (!sd_has_rps_ipi_waiting(sd) && list_empty(&repoll))
- return;
+ goto out;
break;
}
@@ -5278,7 +5278,6 @@ static __latent_entropy void net_rx_action(struct softirq_action *h)
}
}
- __kfree_skb_flush();
local_irq_disable();
list_splice_tail_init(&sd->poll_list, &list);
@@ -5288,6 +5287,8 @@ static __latent_entropy void net_rx_action(struct softirq_action *h)
__raise_softirq_irqoff(NET_RX_SOFTIRQ);
net_rps_action_and_irq_enable(sd);
+out:
+ __kfree_skb_flush();
}
struct netdev_adjacent {