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 id 1TVQw7-0000SL-Nj; Mon, 05 Nov 2012 19:58:11 +0200
To: Joe Holden <lists@rewt.org.uk>
From: Ian FREISLICH <ianf@cloudseed.co.za>
Subject: Re: Dynamic Ticks/HZ
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Cc: Davide Italiano <davide@freebsd.org>, Alexander Motin <mav@FreeBSD.org>,
 FreeBSD Current <freebsd-current@freebsd.org>
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Joe Holden wrote:
> It looks like the device polling is what was causing it, once I'd 
> removed that from kernconf it returned to normal - full interupt rate is 
> ok though if I can increase the rate to a decent level

FWIW, this is how my igb(4) system is tuned and with PF, it's able
to fill 4xigb interfaces:

/boot/loader.conf:
# 16 CPUs
net.isr.maxthreads="8"
net.isr.defaultqlimit="4096"
net.isr.maxqlimit="81920"
net.isr.direct="1"
net.isr.direct_force="1"
net.isr.bindthreads="0"
kern.ipc.nmbclusters="262144"
hw.igb.max_interrupt_rate="32000"
hw.igb.rx_process_limit="500"
hw.igb.header_split="1" #This setting doesn't seem to work
hw.igb.txd="4096"
hw.igb.rxd="4096"

/etc/sysctl.conf:
net.inet.ip.fastforwarding=1
kern.random.sys.harvest.interrupt=0
kern.random.sys.harvest.ethernet=0
kern.random.sys.harvest.point_to_point=0

Ian

-- 
Ian Freislich