Date: Sat, 28 Jun 2008 11:54:05 +1000 From: Andrew Snow <andrew@modulus.org> To: Paul <paul@gtcomm.net>, freebsd-net@freebsd.org Subject: Re: Weirdness - FBSD 7, Routing, Packet generator, em taskq Message-ID: <486599BD.7030804@modulus.org> In-Reply-To: <48653340.8060301@gtcomm.net> References: <48645D9E.7090303@gtcomm.net> <m23amydifl.wl%gnn@neville-neil.com> <48653340.8060301@gtcomm.net>
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Firstly, tried turning off polling? Some of us have found it to be detrimental to performance on the more modern systems. Its use was more practical on older systems were servicing interrupts took alot of CPU power, but the "em" driver supports delaying interrupts until more packets have arrived - see the sysctls available on the em man page. So you're probably better of turning off polling and playing with these tunables, by calculating how many packets you're likely to be able to fit in the tx/rx descriptor array before you need to generate an interrupt. Secondly try pressing shift+c inside top to display "raw cpu usage" instead of the default "weighted cpu usage". Finally, is your test portraying realistic conditions? I am reminded that 1GB/s with 1500 MTU is only roughly 80,000 pps. - Andrew
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