From mboxrd@z Thu Jan 1 00:00:00 1970 From: Brendan Cully Subject: Re: [PATCH] Skip vcpu_hotplug for VCPU 0 in smp_resume Date: Tue, 31 Mar 2009 10:24:25 -0700 Message-ID: <20090331172423.GA70062@zanzibar.lan> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: xen-devel@lists.xensource.com Cc: andy@cs.ubc.ca List-Id: xen-devel@lists.xenproject.org On Tuesday, 31 March 2009 at 09:53, Brendan Cully wrote: > Skip vcpu_hotplug for VCPU 0 in smp_resume. > This function can occasionally take up to 2 seconds to complete, > and smp_suspend also skips VCPU 0. I'm doing a bit of testing ahead of releasing Remus, and I've noticed that there are a couple of places where resuming from suspension can get stuck for a long time, which can cause Remus to think that the domain has died. This is one of them. The other is in the netfront accelerator. It tears down a xenstore watch on the accelerator path at every suspend, and adds the watch back on resume. As with any xenstore interaction, this can occasionally take a very long time. I'm going from faulty memory here, but I didn't think it was necessary to tear down and restore watches across suspend. Would it make sense to move the watch remove and add into the resume hook (taking it completely out of suspend and suspend_cancel)?