From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marcelo Tosatti Subject: Re: [RFC] need to improve slot creation/destruction? -- Re: [RFC][PATCH] srcu: Implement call_srcu() Date: Fri, 10 Feb 2012 15:17:54 -0200 Message-ID: <20120210171754.GB24403@amt.cnet> References: <1328017807.2446.230.camel@twins> <20120131222447.GH2391@linux.vnet.ibm.com> <1328091749.2760.34.camel@laptop> <4F29178A.1090306@redhat.com> <4F2918D5.4050104@redhat.com> <20120201135020.GB18998@amt.cnet> <20120209004320.5772daa0472aef4700dab1b6@gmail.com> <4F33D6C9.2070403@redhat.com> <4F33D711.6020104@redhat.com> <20120210220812.4e2e3a30c7fddf72d4e6e8af@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Avi Kivity , kvm@vger.kernel.org To: Takuya Yoshikawa Return-path: Received: from mx1.redhat.com ([209.132.183.28]:7542 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758384Ab2BJRTx (ORCPT ); Fri, 10 Feb 2012 12:19:53 -0500 Content-Disposition: inline In-Reply-To: <20120210220812.4e2e3a30c7fddf72d4e6e8af@gmail.com> Sender: kvm-owner@vger.kernel.org List-ID: On Fri, Feb 10, 2012 at 10:08:12PM +0900, Takuya Yoshikawa wrote: > Avi Kivity wrote: > > > On 02/09/2012 04:23 PM, Avi Kivity wrote: > > > > BTW do we really need fast slot creation/destruction? > > > > > > Not really, but it's good to have infrastructure that copes with > > > different workloads. If the patches keep the code simple I think it's a > > > good thing to have. > > My patch is pretty simple. > > > To qualify - taking several tens of milliseconds is out of the question > > as some workloads grind to a halt. But it doesn't need to be incredibly > > fast. > > I think the problem is not how long it takes to create/invalidate a slot > but following faults and shadow pages reconstruction. The problem which is immediatelly visible is kvm_set_mem performance. > Similar to mmu shrinker problem we discussed before. > > E.g. users will not expect sudden latency induced by pci hotplug. > > Takuya