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Date: Thu, 10 Oct 2013 00:17:52 -0400 (EDT) From: David Miller <davem@...emloft.net> To: eric.dumazet@...il.com Cc: netdev@...r.kernel.org Subject: Re: [PATCH net-next] net: gro: allow to build full sized skb From: Eric Dumazet <eric.dumazet@...il.com> Date: Tue, 08 Oct 2013 09:02:23 -0700 > From: Eric Dumazet <edumazet@...gle.com> > > skb_gro_receive() is currently limited to 16 or 17 MSS per GRO skb, > typically 24616 bytes, because it fills up to MAX_SKB_FRAGS frags. > > It's relatively easy to extend the skb using frag_list to allow > more frags to be appended into the last sk_buff. > > This still builds very efficient skbs, and allows reaching 45 MSS per > skb. > > (45 MSS GRO packet uses one skb plus a frag_list containing 2 additional > sk_buff) > > High speed TCP flows benefit from this extension by lowering TCP stack > cpu usage (less packets stored in receive queue, less ACK packets > processed) > > Forwarding setups could be hurt, as such skbs will need to be > linearized, although its not a new problem, as GRO could already > provide skbs with a frag_list. > > We could make the 65536 bytes threshold a tunable to mitigate this. > > (First time we need to linearize skb in skb_needs_linearize(), we could > lower the tunable to ~16*1460 so that following skb_gro_receive() calls > build smaller skbs) > > Signed-off-by: Eric Dumazet <edumazet@...gle.com> Applied, thanks Eric. -- 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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