Date: Tue, 19 Nov 2002 14:09:30 +0100 From: Marko Zec <zec@tel.fer.hr> To: Sergey Solyanik <solik@sumy.net> Cc: Dmitry Morozovsky <marck@rinet.ru>, stable@freebsd.org Subject: Re: DEVICE_POLLING and kern.hz Message-ID: <3DDA380A.37355A33@tel.fer.hr> References: <20021118221514.I34951-100000@woozle.rinet.ru> <3DD945D4.2020104@sumy.net>
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Sergey Solyanik wrote: > Dmitry Morozovsky wrote: > > we have FreeBSD router with 4 fxp's and moderately high traffic (up to 15 Mbps > > at upstream port). There is about 2k5-3k5 interrupts per second, about 1k-1k5 > > of them are from fxp0. > > > > Would it be useful to turn on DEVICE_POLLING on this machine? > > Wouldn't be useful just to load microcode into fxpX ? > Try ifconfig fxpX link0 The fxp microcode puts the card into the interrupt coalescing mode, which can be useful for end nodes, but is definitely a BAD THING on routers. Contrary to interrupt coalescing, which can introduce significant delays and thereby cause unnecessary problems with TCP throughput, device polling approach seems to be much better suited for packet forwarding applications, as it won't introduce any additional delay under normal operating conditions. Nevertheless, at traffic rates not regularly exceeding 10.000 packets per second, which seems to be the case in your environment, I don't see any need for employing either interrupt coalescing or device polling at all. Best regards, Marko To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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