From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hollis Blanchard Subject: Re: [RFC] Paravirt timer for KVM Date: Mon, 15 Oct 2007 18:05:40 -0500 Message-ID: <1192489540.22523.32.camel@basalt> References: <5d6222a80710120908s6b1f5845head84e7b7a463cd1@mail.gmail.com> <1192218507.14891.18.camel@basalt> <470FD2CA.1000702@codemonkey.ws> <1192226137.14891.111.camel@basalt> <470FF036.6080803@codemonkey.ws> <10EA09EFD8728347A513008B6B0DA77A023A6DCE@pdsmsx411.ccr.corp.intel.com> <1192464113.25377.0.camel@basalt> <47139994.4030606@qumranet.com> Reply-To: Hollis Blanchard Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel , Jeremy Fitzhardinge To: Avi Kivity Return-path: In-Reply-To: <47139994.4030606-atKUWr5tajBWk0Htik3J/w@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 List-Id: kvm.vger.kernel.org On Mon, 2007-10-15 at 18:47 +0200, Avi Kivity wrote: > Hollis Blanchard wrote: > >> > >> I'd think there is no reason for virtual timer to be PIT like, which > >> is mostly due to historic reason. > >> > >> If we need to make it close to native timer device, HPET is much > >> better than PIT for virtual time to look like. > >> > > > > Fine, so why do we need PV time when we can emulate the HPET? > > > > A pv timebase can require zero exits while any emulated timebase will > require at least one. That's a good point, but does PIT/HPET emulation show up as a hot spot in any profiles? I think keeping the hypercall API as small as feasible is a desirable design goal. -- Hollis Blanchard IBM Linux Technology Center ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/