Date: Tue, 24 Apr 2012 17:03:57 +0200 From: "K. Macy" <kmacy@freebsd.org> To: "Li, Qing" <qing.li@bluecoat.com> Cc: Luigi Rizzo <rizzo@iet.unipi.it>, "current@freebsd.org" <current@freebsd.org>, "net@freebsd.org" <net@freebsd.org> Subject: Re: Some performance measurements on the FreeBSD network stack Message-ID: <CAHM0Q_OQUJ0E6kPXkPTh0LEYP8yCJjfW8Z_NZ5d-cKyaHW-8AQ@mail.gmail.com> In-Reply-To: <B143A8975061C446AD5E29742C531723C7C16A@pwsvl-excmbx-05.internal.cacheflow.com> 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> <B143A8975061C446AD5E29742C531723C7C16A@pwsvl-excmbx-05.internal.cacheflow.com>
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On Tue, Apr 24, 2012 at 4:16 PM, Li, Qing <qing.li@bluecoat.com> wrote: >> > >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 ? > One could try a similar conversion of the L2 table to an rmlock without copy while lock is held. -Kip --=20 =A0 =A0=93The real damage is done by those millions who want to 'get by.' The ordinary men who just want to be left in peace. Those who don=92t want their little lives disturbed by anything bigger than themselves. Those with no sides and no causes. Those who won=92t take measure of their own strength, for fear of antagonizing their own weakness. Those who don=92t like to make waves=97or enemies. =A0 =A0Those for whom freedom, honour, truth, and principles are only literature. Those who live small, love small, die small. It=92s the reductionist approach to life: if you keep it small, you=92ll keep it under control. If you don=92t make any noise, the bogeyman won=92t find you. =A0 =A0But it=92s all an illusion, because they die too, those people who roll up their spirits into tiny little balls so as to be safe. Safe?! >From what? Life is always on the edge of death; narrow streets lead to the same place as wide avenues, and a little candle burns itself out just like a flaming torch does. =A0 =A0I choose my own way to burn.=94 =A0 =A0Sophie Scholl
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