From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:43055) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TBp9O-0002uk-0t for qemu-devel@nongnu.org; Wed, 12 Sep 2012 11:46:53 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TBp9J-0005CJ-W6 for qemu-devel@nongnu.org; Wed, 12 Sep 2012 11:46:49 -0400 Received: from mx1.redhat.com ([209.132.183.28]:40777) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TBp9J-0005C8-Ma for qemu-devel@nongnu.org; Wed, 12 Sep 2012 11:46:45 -0400 Date: Wed, 12 Sep 2012 18:45:20 +0300 From: Gleb Natapov Message-ID: <20120912154520.GU20907@redhat.com> References: <87pq5r5otp.fsf@codemonkey.ws> <50509A66.7010505@siemens.com> <87y5kfi9mt.fsf@codemonkey.ws> <20120912150647.GS20907@redhat.com> <5050AD82.5080606@siemens.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5050AD82.5080606@siemens.com> Subject: Re: [Qemu-devel] Rethinking missed tick catchup List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jan Kiszka Cc: Michael Roth , "qemu-devel@nongnu.org" , Luiz Capitulino , Avi Kivity , Anthony Liguori , Paolo Bonzini , Eric Blake On Wed, Sep 12, 2012 at 05:42:58PM +0200, Jan Kiszka wrote: > On 2012-09-12 17:06, Gleb Natapov wrote: > >>>> Are there other issues with reinjection that people are aware of? Does > >>>> anything seem obviously wrong with the above? > >>> > >>> We should take the chance and design everything in a way that the HPET > >>> can finally be (left) enabled. > >> > >> I thought the issue with the HPET was access frequency and the cost of > >> heavy weight exits. > >> > >> I don't have concrete data here. I've only heard it second hand. Can > >> anyone comment more? > >> > > There is no any reason whatsoever to emulate HPET for Windows. It will > > make it slower. Hyper-V does not emulate it. For proper time support in > > Windows we need to implement relevant part of Hyper-V spec. > > There are two reasons to do it nevertheless: > > - QEMU is not Hyper-V. We are emulating the HPET already, and we > expose it by default. So we should do it properly. > > - The time drift fix for the RTC is still a hack. Adding a second user > would force us to finally clean it up. > I am not saying we should not emulate HPET in QEMU, I am saying there is not reason to emulate it for Windows :) -- Gleb.