From mboxrd@z Thu Jan 1 00:00:00 1970 From: Balbir Singh Subject: Re: [RFC/T/D][PATCH 2/2] Linux/Guest cooperative unmapped page cache control Date: Thu, 17 Jun 2010 11:34:28 +0530 Message-ID: <20100617060428.GH4306@balbir.in.ibm.com> References: <20100614125010.GU5191@balbir.in.ibm.com> <4C162846.7030303@redhat.com> <1276529596.6437.7216.camel@nimitz> <4C164E63.2020204@redhat.com> <1276530932.6437.7259.camel@nimitz> <4C1659F8.3090300@redhat.com> <1276538293.6437.7528.camel@nimitz> <4C1726C4.8050300@redhat.com> <1276613249.6437.11516.camel@nimitz> <4C18B7D6.5070300@redhat.com> Reply-To: balbir@linux.vnet.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Cc: Dave Hansen , kvm , linux-mm@kvack.org, linux-kernel@vger.kernel.org To: Avi Kivity Return-path: Content-Disposition: inline In-Reply-To: <4C18B7D6.5070300@redhat.com> Sender: owner-linux-mm@kvack.org List-Id: kvm.vger.kernel.org * Avi Kivity [2010-06-16 14:39:02]: > >We're talking about an environment which we're always trying to > >optimize. Imagine that we're always trying to consolidate guests on to > >smaller numbers of hosts. We're effectively in a state where we > >_always_ want new guests. > > If this came at no cost to the guests, you'd be right. But at some > point guest performance will be hit by this, so the advantage gained > from freeing memory will be balanced by the disadvantage. > > Also, memory is not the only resource. At some point you become cpu > bound; at that point freeing memory doesn't help and in fact may > increase your cpu load. > We'll probably need control over other resources as well, but IMHO memory is the most precious because it is non-renewable. -- Three Cheers, Balbir -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org