Date: Thu, 19 Apr 2012 23:35:37 +0200 From: "K. Macy" <kmacy@freebsd.org> To: Andre Oppermann <andre@freebsd.org> Cc: Luigi Rizzo <rizzo@iet.unipi.it>, current@freebsd.org, net@freebsd.org Subject: Re: Some performance measurements on the FreeBSD network stack Message-ID: <CAHM0Q_M-QJ5xMCsagKJKbnuaJ-KfRcfd64Efh8HbFkCoiZOdWg@mail.gmail.com> In-Reply-To: <4F908327.5070905@freebsd.org> References: <20120419133018.GA91364@onelab2.iet.unipi.it> <4F907011.9080602@freebsd.org> <20120419204622.GA94904@onelab2.iet.unipi.it> <CAHM0Q_M4wcEiWGkjWxE1OjLeziQN0vM%2B4_EYS_WComZ6=j5xhA@mail.gmail.com> <4F907FB4.3080400@freebsd.org> <CAHM0Q_NwvLVFgeE3xsaf8nO1Nusm4QBp7eRuMn=UuNWWFp0vnw@mail.gmail.com> <4F908327.5070905@freebsd.org>
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> > Yes, but the lookup requires a lock? =A0Or is every entry replicated > to every CPU? =A0So a number of concurrent CPU's sending to the same > UDP destination would content on that lock? No. In the default case it's per CPU, thus no serialization is required. But yes, if your transmitting thread manages to bounce to every core during send within the flow expiration window you'll have an extra 12 or however many bytes per peer times the number of cores. There is usually a fair amount of CPU affinity over a given unit time. --=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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