From owner-freebsd-current Tue Apr 17 20:12:44 2001 Delivered-To: freebsd-current@freebsd.org Received: from a.mx.everquick.net (a.mx.everquick.net [216.89.137.3]) by hub.freebsd.org (Postfix) with ESMTP id 935A137B423 for ; Tue, 17 Apr 2001 20:12:41 -0700 (PDT) (envelope-from eddy+public+spam@noc.everquick.net) Received: from localhost (eddy@localhost) by a.mx.everquick.net (8.10.2/8.10.2) with ESMTP id f3I3Bwh15485; Wed, 18 Apr 2001 03:11:58 GMT X-EverQuick-No-Abuse: Report any e-mail abuse to Date: Wed, 18 Apr 2001 03:11:57 +0000 (GMT) From: "E.B. Dreger" To: Rik van Riel Cc: Matt Dillon , Alfred Perlstein , Greg Lehey , "Justin T. Gibbs" , Doug Barton , "current @ freebsd . org" Subject: Re: Kernel preemption, yes or no? (was: Filesystem gets a huge performance boost) In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG > Date: Wed, 18 Apr 2001 00:04:12 -0300 (BRST) > From: Rik van Riel > > 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