From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH] memory: synchronize dirty bitmap before unmapping a range Date: Mon, 01 Aug 2011 12:30:24 +0300 Message-ID: <4E367230.6020705@redhat.com> References: <1312141678-5141-1-git-send-email-avi@redhat.com> <4E365718.2060500@web.de> <4E365B3A.7050701@web.de> <4E3660C9.3000708@redhat.com> <4E366C56.90705@siemens.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Cc: Anthony Liguori , qemu-devel@nongnu.org, kvm@vger.kernel.org To: Jan Kiszka Return-path: Received: from mx1.redhat.com ([209.132.183.28]:51174 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752856Ab1HAJad (ORCPT ); Mon, 1 Aug 2011 05:30:33 -0400 In-Reply-To: <4E366C56.90705@siemens.com> Sender: kvm-owner@vger.kernel.org List-ID: On 08/01/2011 12:05 PM, Jan Kiszka wrote: > On 2011-08-01 10:16, Avi Kivity wrote: > > On 08/01/2011 10:52 AM, Jan Kiszka wrote: > >> On 2011-08-01 09:34, Jan Kiszka wrote: > >> > On 2011-07-31 21:47, Avi Kivity wrote: > >> >> When a range is being unmapped, ask accelerators (e.g. kvm) to > >> synchronize the > >> >> dirty bitmap to avoid losing information forever. > >> >> > >> >> Fixes grub2 screen update. > >> > > >> > I does. > >> > > >> > But something is still broken. As I reported before, the > >> performance of > >> > grub2 startup is an order of magnitude slower than with the existing > >> > code. According to ftrace, we are getting tons of additional > >> > EPT_MISCONFIG exits over the 0xA0000 segment. But I haven't spot the > >> > difference yet. The effective slot setup as communicated to kvm looks > >> > innocent. > >> > >> I take it back: We obviously once in a while resume the guest with the > >> vga segment unmapped. And that, of course, ends up doing mmio instead of > >> plain ram accesses. > >> > > > > qemu-kvm.git 6b5956c573 and its predecessor fix the issue (and I think > > they're even faster than upstream, but perhaps I'm not objective). > > > > Just updated to the latest memory-region branch - how did you test it? opensuse 11.4 > It does not link here due to forgotten rwhandler in Makefile.target. > I probably still have it in my tree, will update and re-push. > Anyway, that commit has no impact on the issue I'm seeing. I'm also > carrying transaction changes for cirrus here, but they have no > noticeable impact. That indicates that the new API is not actually slow, > it likely just has some bug. It should be visible from the memory map dump. -- error compiling committee.c: too many arguments to function