Date: Fri, 01 Feb 2002 03:57:04 -0800 From: Terry Lambert <tlambert2@mindspring.com> To: Alfred Perlstein <bright@mu.org> Cc: Luigi Rizzo <rizzo@icir.org>, Mike Silbersack <silby@silby.com>, Storms of Perfection <gary@outloud.org>, thierry@herbelot.com, replicator@ngs.ru, hackers@FreeBSD.org Subject: Re: Clock Granularity (kernel option HZ) Message-ID: <3C5A8290.216BB28C@mindspring.com> References: <20020131172729.X38382-100000@patrocles.silby.com> <3C59E873.4E8A82B5@mindspring.com> <20020201002339.C48439@iguana.icir.org> <20020201002835.I18604@elvis.mu.org>
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Alfred Perlstein wrote: > Forwarding packets is a lot less complicated than doing tcp > recieve and send. I haven't seen Terry's stuff in action, > however it makes sense that tcp would see more of an improvement > than simple IP forwarding. I guess you are talking the LRP stuff. I was just talking about the processing at NETISR as a result of a higher HZ causing a higher softintr run frequency. Really, the timer code that TCP uses is all bogus for a large number of connections, and upping the clock wheel size doesn't gain you nearly as much as interval specific lists which only have to process until the intended time to fire is later than "now". The clock stuff as it is has to traverse the entire chain, because it can't know that the firing of the timer after the current one is later than the current one (i.e. intervals of 1 second and one hour can end up in the same wheel bucket, because it is, in effect, an unsorted modular timer, and inserting sorted for more than one or two intervals is an O(N) problem). -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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