Date: Tue, 1 Jul 2008 11:05:03 +0800 From: "Sepherosa Ziehau" <sepherosa@gmail.com> To: Paul <paul@gtcomm.net> Cc: freebsd-net@freebsd.org, Ingo Flaschberger <if@xip.at>, "Wilkinson, Alex" <alex.wilkinson@dsto.defence.gov.au>, "Support \(Rudy\)" <crapsh@monkeybrains.net> Subject: Re: Freebsd IP Forwarding performance (question, and some info) [7-stable, current, em, smp] Message-ID: <ea7b9c170806302005n2a66f592h2127f87a0ba2c6d2@mail.gmail.com> In-Reply-To: <48699960.9070100@gtcomm.net> References: <4867420D.7090406@gtcomm.net> <200806301944.m5UJifJD081781@lava.sentex.ca> <20080701004346.GA3898@stlux503.dsto.defence.gov.au> <alpine.LFD.1.10.0807010257570.19444@filebunker.xip.at> <20080701010716.GF3898@stlux503.dsto.defence.gov.au> <alpine.LFD.1.10.0807010308320.19444@filebunker.xip.at> <486986D9.3000607@monkeybrains.net> <48699960.9070100@gtcomm.net>
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On 7/1/08, Paul <paul@gtcomm.net> wrote: > All the NIC drivers in 7 pretty much use interrupt moderation so it can I am not quite sure whether em(4)'s RX interrupt moderation works as expected or not. But, AFAIK, nfe(4) and re(4) does not have RX interrupt moderation. Their TX interrupt moderation could be mimiced by using their hardware timer and disabling their TX interrupt. The lacking of RX im is difficult to handle, I could imagine following way: - During init, enable RX intr - When RX intr comes, disable RX intr and set up hardware timer intr - When timer intr comes and no RX happens, disable timer intr and enable RX intr Properly configured #RX desc and timer intr interval will be required to make sure that the RX desc collection could keep up with the hardware speed. I used pure timer intr (8000Hz) on nfe(4) in dfly w/ good result, i.e. TX/RX @linespeed without livelocking the system. The drawback of pure timer intr is that you waste extra cpu power, when there is nothing to process. > never lock the machine anyway.. This effectively kills polling and it really > no longer has any use except to be able to have a fraction of the cpu set Oh? Really? :] Best Regards, sephe -- Live Free or Die
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