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Date: Wed, 12 Dec 2012 22:13:02 +0800 From: Weiping Pan <panweiping3@...il.com> To: David Miller <davem@...emloft.net> CC: wpan@...hat.com, netdev@...r.kernel.org, brutus@...gle.com Subject: Re: [RFC PATCH net-next 0/3 V4] net-tcp: TCP/IP stack bypass for loopback connections On 12/11/2012 05:02 AM, David Miller wrote: > From: Weiping Pan<wpan@...hat.com> > Date: Wed, 5 Dec 2012 10:54:16 +0800 > >> Friends VS AF__UNIX >> Their call path are almost the same, but AF_UNIX uses its own send/recv codes >> with proper locks, >> so AF_UNIX's performance is much better than Friends. Sorry, this statement is not correct. In TCP_STREAM case, if the message size if 16384, then AF_UNIX is much better than Friends. If the message size is smaller, then Friends shows equal performance with AF_UNIX. In TCP_RR, Friends shows equal performance with AF_UNIX, too. > While I understand the other portions of your analysis, this one > mystifies me. > > In both cases, the sender has to queue the SKB onto the receiver's > queue. And in both cases, the sender takes the lock on that queue. > > So the locking contention really ought to be similar if not identical. > > The only difference is that AF_UNIX takes the unix_sk()->lock of the > remote socket around these operations. > > If that is enough of a synchronizer to "fix" the contention or reduce > it, then this would be very easy to test by adding a friend lock to > tcp_sk(). I make some experiments to reduce the use of lock, some performance results will be followed up. thanks Weiping Pan > -- > 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 > -- 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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