Date: Tue, 24 Apr 2012 14:16:18 +0000 From: "Li, Qing" <qing.li@bluecoat.com> To: Luigi Rizzo <rizzo@iet.unipi.it> Cc: "current@freebsd.org" <current@freebsd.org>, "net@freebsd.org" <net@freebsd.org> Subject: RE: Some performance measurements on the FreeBSD network stack Message-ID: <B143A8975061C446AD5E29742C531723C7C16A@pwsvl-excmbx-05.internal.cacheflow.com> In-Reply-To: <20120424140228.GA58809@onelab2.iet.unipi.it> References: <20120419133018.GA91364@onelab2.iet.unipi.it> <4F907011.9080602@freebsd.org> <20120419204622.GA94904@onelab2.iet.unipi.it> <4F96A7C0.3010909@freebsd.org>, <20120424140228.GA58809@onelab2.iet.unipi.it>
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> >From previous tests, the difference between flowtable and >routing table was small with a single process (about 5% or 50ns >in the total packet processing time, if i remember well), >but there was a large gain with multiple concurrent processes. > Yes, that sounds about right when we did the tests a long while ago. > > Removing flowtable increases the cost in ip_output() > (obviously) but also in ether_output() (because the > route does not have a lle entry so you need to call > arpresolve on each packet). > Yup. > > So in revising the route lookup i believe it would be good > if we could also get at once most of the info that > ether_output() is computing again and again. > Well, the routing table no longer maintains any lle info, so there isn't much to copy out the rtentry at the completion of route lookup. If I understood you correctly, you do believe there is a lot of value in Flowtable caching concept, but you are not suggesting we reverting back to having the routing table maintain L2 entries, are you ? --Qinghelp
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