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Date: Thu, 05 Apr 2007 16:48:41 +0200 From: Patrick McHardy <kaber@...sh.net> To: leon zadorin <leonleon77@...il.com> CC: linux-kernel@...r.kernel.org Subject: Re: "no hz"/"dynamic tick" option and TC/TBF (token bucket filter) behaviour... leon zadorin wrote: > 2) for kernels which do have the aforementioned option enabled: how > does this affect the "tc" (traffic control) utility and the Token > Bucket Filter (tbf) queueing discipline (traffic-smoothing) > behhaviour? > > For example, the TBF doco suggests that due to the whole fixed Hz > thing in the kernel (e.g. 100Hz) the maximum rate of the TBF would > actually be limited to say 1mbit on Intel arch (with the default > mtu... but if mtu is incleased, so is the burstiness of the traffic > which is what TBF is trying to prevent in my deployment scenarios). > ... > > So what about the kernels which use this "dyna tick" option - in such > a kernel, will there be an interrupt generated (e.g. at microsec. > precision on most platforms) for every packet's send time (e.g. say at > TBF's rate is at 25Mbps and one sends out 1KB data packets... will > there be an interrput generated every... 300 microseconds?)... No, it doesn't affect the timer resolution. net-2.6.22 includes patches that switch all qdiscs to hrtimers, which allows to use much smaller burst rates. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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