Date: Wed, 18 Apr 2001 03:11:57 +0000 (GMT) From: "E.B. Dreger" <eddy+public+spam@noc.everquick.net> To: Rik van Riel <riel@conectiva.com.br> Cc: Matt Dillon <dillon@earth.backplane.com>, Alfred Perlstein <bright@wintelcom.net>, Greg Lehey <grog@lemis.com>, "Justin T. Gibbs" <gibbs@scsiguy.com>, Doug Barton <DougB@DougBarton.net>, "current @ freebsd . org" <current@FreeBSD.ORG> Subject: Re: Kernel preemption, yes or no? (was: Filesystem gets a huge performance boost) Message-ID: <Pine.LNX.4.20.0104180307220.15456-100000@www.everquick.net> In-Reply-To: <Pine.LNX.4.21.0104180002340.14442-100000@imladris.rielhome.conectiva>
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> Date: Wed, 18 Apr 2001 00:04:12 -0300 (BRST) > From: Rik van Riel <riel@conectiva.com.br> > > Not true. Interrupts work worse than polling because the interrupt > top halves can keep the CPU busy, whereas with polling you only Top halves and _task switching_. Again, in a well-written handler with a tight loop, task switching becomes expensive. > peek at the card when you have time. Think aio_xxxx versus kernel queues. :-) > This means pure interrupts can possibly DoS a CPU (think about a > gigabit ping flood) while polling leaves the box alive and still > allows it to process as much as it can (while not wasting CPU on > taking in packets it cannot process higher up the stack). I should hope that the card would be smart enough to combine consecutive packets into a single DMA transfer, but I know what you mean. Eddy --------------------------------------------------------------------------- Brotsman & Dreger, Inc. EverQuick Internet / EternalCommerce Division Phone: (316) 794-8922 --------------------------------------------------------------------------- To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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