From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bob Liu Subject: Re: A good way to speed up the xl destroy time(guest page scrubbing) Date: Sun, 07 Dec 2014 21:43:22 +0800 Message-ID: <5484597A.507@oracle.com> References: <546F1033.7030005@oracle.com> <54818221.1070804@oracle.com> <5481B1F6020000780004D24A@mail.emea.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta4.messagelabs.com ([85.158.143.247]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1Xxc8e-0005I3-MS for xen-devel@lists.xenproject.org; Sun, 07 Dec 2014 13:44:40 +0000 In-Reply-To: <5481B1F6020000780004D24A@mail.emea.novell.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Jan Beulich Cc: George.Dunlap@eu.citrix.com, andrew.cooper3@citrix.com, ian.campbell@citrix.com, xen-devel List-Id: xen-devel@lists.xenproject.org On 12/05/2014 08:24 PM, Jan Beulich wrote: >>>> On 05.12.14 at 11:00, wrote: >> 5. Potential workaround >> 5.1 Use per-cpu list in idle_loop() >> Delist a batch of pages from heap_list to a per-cpu list, then scrub the >> per-cpu list and free back to heap_list. >> >> But Jan disagree with this solution: >> "You should really drop the idea of removing pages temporarily. >> All you need to do is make sure a page being allocated and getting >> simultaneously scrubbed by another CPU won't get passed to the >> caller until the scrubbing finished." > > So you don't mention any downsides to this approach. If there are > any, please name them. If there aren't, what's the reason not to > go this route? The reason was what you suggested was not very specific, I still have no idea how to implement a patch which can "make sure a page being allocated and getting simultaneously scrubbed by another CPU won't get passed to the caller until the scrubbing finished". Thanks, -Bob