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Message-ID: <m2n412e6f7f1004220103g140ef833wb41105a491e75ae1@mail.gmail.com> Date: Thu, 22 Apr 2010 16:03:21 +0800 From: Changli Gao <xiaosuo@...il.com> To: Eric Dumazet <eric.dumazet@...il.com> Cc: Stephen Hemminger <shemminger@...tta.com>, "David S. Miller" <davem@...emloft.net>, jamal <hadi@...erus.ca>, Tom Herbert <therbert@...gle.com>, netdev@...r.kernel.org Subject: Re: [PATCH v4] net: batch skb dequeueing from softnet input_pkt_queue On Thu, Apr 22, 2010 at 3:21 PM, Eric Dumazet <eric.dumazet@...il.com> wrote: > Jamal perf reports show lock contention but also cache line ping pongs. > > Yet, you keep a process_queue_len shared by producers and consumer. > > Producers want to read it, while consumer decrement it (dirtying its > cache line) every packet, slowing down the things. > > > The idea of batching is to let the consumer process its local queue with > no impact to producers. > > Please remove it completely, or make the consumer zero it only at the > end of batch processing. > > A cache line miss cost is about 120 cycles. Multiply it by 1 million > packet per second... > OK, I'll remove it, and update the input_pkt_queue only before process_backlog returns. -- Regards, Changli Gao(xiaosuo@...il.com) -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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