Date: Fri, 12 Mar 1999 07:28:35 +1000 From: Peter Jeremy <peter.jeremy@AUSS2.ALCATEL.COM.AU> To: dg@root.com Cc: freebsd-bugs@FreeBSD.ORG, semen@iclub.nsu.ru Subject: Re: kern/10535: Very poor ethernet performance with tx driver Message-ID: <99Mar12.071637est.40398@border.alcanet.com.au>
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David Greenman <dg@root.com> wrote: > The real question in my mind is why does the driver frob with the PHY >in a critical path? That's guaranteed to cause the performance to suck, no >matter what you do with the for-loops. At the beginning of epic_ifstart(), there is a check that the link is up, otherwise the mbufs are dropped in the bit bucket. I'm not sure why the link status has to be read twice. At least it is only once per packet. If a PII-450 is intermittent with a loop count of 0x1000 and 5 insns per loop with no memory references, that suggests that the chip takes ~~50usec to respond. I can't answer this, and I can't find any technical information on the SMC website. Maybe Semen (as the driver author) can comment. Peter To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-bugs" in the body of the message
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