From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Campbell Subject: Re: [PATCH v3 COLOPre 17/26] tools/libx{l, c}: introduce should_checkpoint callback Date: Wed, 1 Jul 2015 11:43:41 +0100 Message-ID: <1435747421.21469.254.camel@citrix.com> References: <1435213552-10556-1-git-send-email-yanghy@cn.fujitsu.com> <1435213552-10556-18-git-send-email-yanghy@cn.fujitsu.com> <1435659599.21469.75.camel@citrix.com> <559353BF.1090405@cn.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <559353BF.1090405@cn.fujitsu.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: Yang Hongyang Cc: wei.liu2@citrix.com, wency@cn.fujitsu.com, andrew.cooper3@citrix.com, yunhong.jiang@intel.com, eddie.dong@intel.com, xen-devel@lists.xen.org, guijianfeng@cn.fujitsu.com, rshriram@cs.ubc.ca, ian.jackson@eu.citrix.com List-Id: xen-devel@lists.xenproject.org On Wed, 2015-07-01 at 10:43 +0800, Yang Hongyang wrote: > > On 06/30/2015 06:19 PM, Ian Campbell wrote: > > On Thu, 2015-06-25 at 14:25 +0800, Yang Hongyang wrote: > >> Under COLO, we are doing checkpoint on demand, if this > >> callback returns 1, we will take another checkpoint. > >> 0 indicates unexpected error. > > > > Is this checkpoint therefore expected to be blocking until another > > checkpoint is desired (or an error occurs)? > > Right. IMHO this should therefore be documented. Some care will need to be taken to avoid blocking any non-async part of the main libxl process. The means by which this is achieved (which I suppose is that the call back is in the context of the helper process) should be mentioned in the commit message. Ian.