Date: Wed, 18 Apr 2001 00:04:12 -0300 (BRST) From: Rik van Riel <riel@conectiva.com.br> To: Matt Dillon <dillon@earth.backplane.com> Cc: "E.B. Dreger" <eddy+public+spam@noc.everquick.net>, 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.4.21.0104180002340.14442-100000@imladris.rielhome.conectiva> In-Reply-To: <200104180234.f3I2Yuq17047@earth.backplane.com>
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On Tue, 17 Apr 2001, Matt Dillon wrote: > Under a full load polling would work just as well as an interrupt. > With NT for the network tests they hardwired each NIC to a particular > CPU. I don't know if they did any polling or not. Not true. Interrupts work worse than polling because the interrupt top halves can keep the CPU busy, whereas with polling you only peek at the card when you have time. 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). regards, Rik -- Virtual memory is like a game you can't win; However, without VM there's truly nothing to lose... http://www.surriel.com/ http://www.conectiva.com/ http://distro.conectiva.com.br/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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