From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeremy Fitzhardinge Subject: Re: [PATCH 5/5] KVM: paravirt time source Date: Tue, 19 Jun 2007 14:26:38 -0700 Message-ID: <46784A0E.3080502@goop.org> References: <4675F462.1010708@codemonkey.ws> <4675F601.3090706@codemonkey.ws> <4676D8E4.3020806@goop.org> <46783EDB.5010808@codemonkey.ws> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <46783EDB.5010808-rdkfGonbjUSkNkDKm+mE6A@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org To: Anthony Liguori Cc: kvm-devel , virtualization List-Id: virtualization@lists.linuxfoundation.org Anthony Liguori wrote: > I've updated this patch and switched to using a scale/shift like Xen > is doing, but I must admit, I don't understand how it helps adjtime. > I poked around a bit and it wasn't obvious. > > Why is having {mult=1<<22, shift=22} better for adjtime than {mult=1, > shift=0}? I don't fully understand it myself, but I think its because adjtime plays with the mult factor to scale the rate at which time passes. If the scale is 1, then it can only scale time by integer amounts. By setting it to 2^22, then it can adjust time down to 1 part in 4 million. J ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/