From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ingo Molnar Subject: Re: [PATCH v2 2/2] x86: Raise the hard VCPU count limit Date: Thu, 21 Jul 2011 11:24:19 +0200 Message-ID: <20110721092419.GQ9216@elte.hu> References: <1310729869-1451-1-git-send-email-levinsasha928@gmail.com> <1310729869-1451-2-git-send-email-levinsasha928@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: kvm@vger.kernel.org, Avi Kivity , Marcelo Tosatti , Pekka Enberg To: Sasha Levin Return-path: Received: from mx2.mail.elte.hu ([157.181.151.9]:39851 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750834Ab1GUJZI (ORCPT ); Thu, 21 Jul 2011 05:25:08 -0400 Content-Disposition: inline In-Reply-To: <1310729869-1451-2-git-send-email-levinsasha928@gmail.com> Sender: kvm-owner@vger.kernel.org List-ID: * Sasha Levin wrote: > The patch raises the hard limit of VCPU count to 254. > > This will allow developers to easily work on scalability > and will allow users to test high VCPU setups easily without > patching the kernel. > > To prevent possible issues with current setups, KVM_CAP_NR_VCPUS > now returns the recommended VCPU limit (which is still 64) - this > should be a safe value for everybody, while a new KVM_CAP_MAX_VCPUS > returns the hard limit which is now 254. > > Cc: Avi Kivity > Cc: Ingo Molnar > Cc: Marcelo Tosatti > Cc: Pekka Enberg > Suggested-by: Pekka Enberg > Signed-off-by: Sasha Levin It would be nice to document the various internal limits that are present (255, etc.) and which prevent further raising of KVM_MAX_VCPUS. This information got mapped out in this discussion, but the commit loses it so it would be nice to preserve it somewhere (at least in the changelog). Thanks, Ingo