Date: Sun, 29 Mar 2015 18:58:55 +0300 From: Slawa Olhovchenkov <slw@zxy.spb.ru> To: Adrian Chadd <adrian@freebsd.org> Cc: "freebsd-hackers@freebsd.org" <freebsd-hackers@freebsd.org> Subject: Re: irq cpu binding Message-ID: <20150329155855.GO23643@zxy.spb.ru> In-Reply-To: <CAJ-Vmo=zzg82rk_jnsCVJCG8qp-fAWWYfcjpbxBznJH39cBTxA@mail.gmail.com> References: <20150328224634.GH23643@zxy.spb.ru> <CAJ-VmokwGgHGP6AjBcGbyJShBPX6dyJjjNeCBcjxLi1obaiRtQ@mail.gmail.com> <20150328230533.GI23643@zxy.spb.ru> <CAJ-VmongWE_z7Rod8-SoFmyiLqiTbHtSaAwjgAs05L_Z3jrWXA@mail.gmail.com> <20150328234116.GJ23643@zxy.spb.ru> <CAJ-VmokSHHm3kMwz=bp7VbgZwADD2_pEr27NdzUfkGq1U=x_sw@mail.gmail.com> <20150329003354.GK23643@zxy.spb.ru> <CAJ-VmonmeeTaSOpSJCJTP7yTeno1LEt-dt9wEhNHk36oY6yY7Q@mail.gmail.com> <20150329081902.GN23643@zxy.spb.ru> <CAJ-Vmo=zzg82rk_jnsCVJCG8qp-fAWWYfcjpbxBznJH39cBTxA@mail.gmail.com>
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On Sun, Mar 29, 2015 at 08:20:25AM -0700, Adrian Chadd wrote: > >> The other half of the network stack - the sending side - also needs to > >> be either on the same or nearby CPU, or you still end up with lock > >> contention and cache thrashing. > > > > For incoming connections this will be automatuc -- sending will be > > from CPU binding to receiving queue. > > > > Outgoing connections is more complex case, yes. > > Need to transfer FD (with re-binding) and signaling (from kernel to > > application) about prefered CPU. Prefered CPU is CPU give SYN-ACK. > > And this need assistance from application. But I am currently can't > > remember application massive servering outgouing connections. > > Or you realise you need to rewrite your userland application so it > doesn't have to do this, and instead uses an IOCP/libdispatch style IO > API to register for IO events and get IO completions to occur in any > given completion thread. nginx is multi-process application, not multi-thread, for example. > Then it doesn't have to care about moving descriptors around - it just > creates an outbound socket, and then the IO completion callbacks will > happen wherever they need to happen. If that needs to shuffle around > due to RSS rebalancing then it'll "just happen". > > And yeah, I know of plenty of applications doing massive outbound > connections - anything being an intermediary HTTP proxy. :) Hmm, yes and no :) Yes, proxy do outbound connections, but proxy crossover inbound and outbound connections and in general this connections pined to different CPU. Is this perfomance gain?..
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