From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keir Fraser Subject: Re: Is patches/linux-2.6.18/xen-hotplug.patch still necessary? Date: Wed, 09 May 2007 16:32:29 +0100 Message-ID: References: <1178723240.6512.2.camel@lappy> Mime-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1178723240.6512.2.camel@lappy> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Alex Williamson Cc: xen-devel List-Id: xen-devel@lists.xenproject.org On 9/5/07 16:07, "Alex Williamson" wrote: >> It has to be handled in top itself. With some versions at least it was the >> case that top would crash when CPUs where hot-unplugged. If you revert that >> patch, does your version of top work okay in the hot-unplug case (you have >> to run top across the unplug operation to see if it will crash or not)? > > Top still crashes without that patch, but the patch just hides the > problem. Top also crashes during a CPU hotplug operation on bare metal. > I think this patch causes more problems than if fixes. Thanks, The fact that physical CPU hotplug is an incredibly rare operation, even on the 0.001% of all systems that it is actually supported on, compared with virtual CPU hotplug being potentially quite frequent, is a real concern. Users are actually moderately likely to see this bug when running on Xen. In fact they used to, and then they complained to us, at which point we applied the band-aid solution. -- Keir