From: Eric Dumazet <eric.duma...@gmail.com> Date: Wed, 23 Nov 2016 08:44:56 -0800
> From: Eric Dumazet <eduma...@google.com> > > 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 <eduma...@google.com> > Cc: Jesper Dangaard Brouer <bro...@redhat.com> > Cc: Alexander Duyck <alexander.h.du...@intel.com> Applied.
