From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:38736) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RgIbi-0000W5-Vi for qemu-devel@nongnu.org; Thu, 29 Dec 2011 11:13:31 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1RgIbh-0006O7-UO for qemu-devel@nongnu.org; Thu, 29 Dec 2011 11:13:30 -0500 Received: from mx1.redhat.com ([209.132.183.28]:46912) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1RgIbh-0006Ny-M7 for qemu-devel@nongnu.org; Thu, 29 Dec 2011 11:13:29 -0500 Message-ID: <4EFC91A0.6050100@redhat.com> Date: Thu, 29 Dec 2011 18:13:20 +0200 From: Avi Kivity MIME-Version: 1.0 References: <20111219083141.32311.9429.stgit@abhimanyu.in.ibm.com> <20111219112326.GA15090@elte.hu> <87sjke1a53.fsf@abhimanyu.in.ibm.com> <4EF1B85F.7060105@redhat.com> <877h1o9dp7.fsf@linux.vnet.ibm.com> <20111223103620.GD4749@elte.hu> <4EF701C7.9080907@redhat.com> <87vcp4t45p.fsf@linux.vnet.ibm.com> <4EF838BD.60406@redhat.com> <4EFC903C.3030509@redhat.com> In-Reply-To: <4EFC903C.3030509@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] Better qemu/kvm defaults (was Re: [RFC PATCH 0/4] Gang scheduling in CFS) List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: dlaor@redhat.com Cc: Anthony Liguori , qemu-devel , Nikunj A Dadhania , kvm-devel On 12/29/2011 06:07 PM, Dor Laor wrote: > On 12/26/2011 11:05 AM, Avi Kivity wrote: >> On 12/26/2011 05:14 AM, Nikunj A Dadhania wrote: >>>> >>>> btw you can get an additional speedup by enabling x2apic, for >>>> default_send_IPI_mask_logical(). >>>> >>> In the host? >>> >> >> In the host, for the guest: >> >> qemu -cpu ...,+x2apic >> > > It seems to me that we should improve our default flags. > So many times users fail to submit the proper huge command-line > options that we require. Honestly, we can't blame them, there are so > many flags and so many use cases its just too hard to get it right for > humans. > > I propose a basic idea and folks are welcome to discuss it: > > 1. Improve qemu/kvm defaults > Break the current backward compatibility (but add a --default- > backward-compat-mode) This exists, -M pc-1.0. > and set better values for: > - rtc slew time > - cache=none > - x2apic, maybe enhance qemu64 or move to -cpu host? We tried this for 1.0, but it caused regressions. Need to try again for 1.1. > - aio=native|threads (auto-sense?) > - use virtio devices by default Can't install non-Linux guests. > - more? > > Different defaults may be picked automatically when TCG|KVM used. -- error compiling committee.c: too many arguments to function