Date: Tue, 12 Jun 2007 11:23:06 -0700 From: Alfred Perlstein <alfred@freebsd.org> To: Robert Watson <watson@FreeBSD.org> Cc: src-committers@freebsd.org, Andre Oppermann <andre@freebsd.org>, Kip Macy <kip.macy@gmail.com>, cvs-all@freebsd.org, Jack Vogel <jfvogel@gmail.com>, cvs-src@freebsd.org, Sam Leffler <sam@errno.com> Subject: Re: cvs commit: src/sys/net if.h Message-ID: <20070612182306.GQ96936@elvis.mu.org> In-Reply-To: <20070612004916.A63490@fledge.watson.org> References: <200706112008.l5BK8CQ7033543@repoman.freebsd.org> <466DACD6.4040606@errno.com> <2a41acea0706111330v6a39cf84o495f6acf62ba7ff7@mail.gmail.com> <2a41acea0706111333p5349993dg9315bfe8396f78a@mail.gmail.com> <466DB362.8010902@freebsd.org> <2a41acea0706111346l227b1399jd80d85771345d8be@mail.gmail.com> <466DB70D.8080800@freebsd.org> <2a41acea0706111403l5f4e1db1re2c901670e327485@mail.gmail.com> <b1fa29170706111554u6308df0cg2b4f6208672a1620@mail.gmail.com> <20070612004916.A63490@fledge.watson.org>
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* Robert Watson <watson@FreeBSD.org> [070611 17:24] wrote: > > On Mon, 11 Jun 2007, Kip Macy wrote: > > >>I think its a windowism, stands for Receive Side Scaling, and what it > >>means is multiple receive queues, each with an MSI/X vector so they can > >>interrupt different CPUs, or they can be tied to virtual guests, or MACs, > >>etc etc... > > > >AFAICT FreeBSD can't currently benefit from this as there is no cpu > >affinity for connections. I may be wrong, but I see lower > >single-connection throughput using a receive queue per core than using a > >single receive queue. RSS is done by hashing a TCP tuple (I'm deliberately > >vague because at least with cxgb there are multiple combinations, the > >default is the standard 4-tuple) to a receive queue. > > If you're looking at concurrent TCP input processing, the tcbinfo lock is > likely one source of overhead due to high contention. I had hoped to make > further progress on this for 7.0 (it's already better than 6.0 in a number > of ways), but the instability of 7.x over the last month scuttled that > project. It will have to be an 8.0 thing, but perhaps we can look at an MFC > if that goes well. I have some initial protyping but have been waiting for > TCP to settle down again a bit before really digging in. Robert, have you added placeholder fields to objects that require them for support? This would help the MFC effort. -- - Alfred Perlstein
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