From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gleb Natapov Subject: Re: [PATCH 22/24] KVM: x86 emulator: restart string instruction without going back to a guest. Date: Tue, 9 Mar 2010 20:11:57 +0200 Message-ID: <20100309181157.GF9066@redhat.com> References: <1268143762-4000-1-git-send-email-gleb@redhat.com> <1268143762-4000-23-git-send-email-gleb@redhat.com> <4B966035.2050904@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: kvm@vger.kernel.org To: Avi Kivity Return-path: Received: from mx1.redhat.com ([209.132.183.28]:19986 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755227Ab0CISL6 (ORCPT ); Tue, 9 Mar 2010 13:11:58 -0500 Received: from int-mx05.intmail.prod.int.phx2.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.18]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id o29IBwmt024309 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Tue, 9 Mar 2010 13:11:58 -0500 Content-Disposition: inline In-Reply-To: <4B966035.2050904@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On Tue, Mar 09, 2010 at 04:50:29PM +0200, Avi Kivity wrote: > On 03/09/2010 04:09 PM, Gleb Natapov wrote: > >Currently when string instruction is only partially complete we go back > >to a guest mode, guest tries to reexecute instruction and exits again > >and at this point emulation continues. Avoid all of this by restarting > >instruction without going back to a guest mode. > > What happens if rcx is really big? Going back into the guest gave > us a preemption point. > Two solutions. We can check if reschedule is required and yield cpu if needed. Or we can enter guest from time to time. -- Gleb.