From owner-freebsd-hackers Thu Jul 2 10:07:32 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id KAA28138 for freebsd-hackers-outgoing; Thu, 2 Jul 1998 10:07:32 -0700 (PDT) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from terra.Sarnoff.COM (terra.sarnoff.com [130.33.11.203]) by hub.freebsd.org (8.8.8/8.8.8) with SMTP id KAA28131 for ; Thu, 2 Jul 1998 10:07:29 -0700 (PDT) (envelope-from rminnich@Sarnoff.COM) Received: (from rminnich@localhost) by terra.Sarnoff.COM (8.6.12/8.6.12) id NAA02473; Thu, 2 Jul 1998 13:06:24 -0400 Date: Thu, 2 Jul 1998 13:06:24 -0400 (EDT) From: "Ron G. Minnich" X-Sender: rminnich@terra To: Luigi Rizzo cc: hackers@FreeBSD.ORG Subject: Re: timeout granularity (was: Re: Console driver...) In-Reply-To: <199807021418.QAA12618@labinfo.iet.unipi.it> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG > do you have a patch for the above ? I think most things work fine with > HZ>100 but i have heard that NTP has problems with it. well, this is embarassing. I did the patch on linux and the machine crashed and took the hard disk with it ... all i did was changed the constant put into the timer interrupt by dividing it by a constant factor. Then in hardclock I counted that constant factor times as many interrupts before causing a softclock interrupt. That way, I kept accurate time. I made it a compile time constant so that a rebuild of the clock code would allow me to tweak it. The test was to vary the interrupt rate and then run a program that counted to 10e10. I measured the wall-clock time it took the program to complete. at 2500 interrupts per second the degradation was (maybe) 1%. At 10k IPS degradation was at about 20%. This was a 486/25. I expect we now with P200+ have lots of power to accomodate 10k IPS but I have not tried it. ron To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message