From mboxrd@z Thu Jan 1 00:00:00 1970 From: Simon Horman Date: Wed, 14 Nov 2007 22:11:33 +0000 Subject: Re: [PATCH] XPC heartbeat timer function must run on CPU 0 Message-Id: <20071114221128.GF2368@verge.net.au> List-Id: References: <20071107135306.99AAF11C415@aqua.americas.sgi.com> In-Reply-To: <20071107135306.99AAF11C415@aqua.americas.sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org On Wed, Nov 14, 2007 at 03:12:38PM -0600, Robin Holt wrote: > On Wed, Nov 14, 2007 at 12:49:14PM -0800, Simon Horman wrote: > > On Thu, Nov 08, 2007 at 06:11:19AM -0600, Dean Nelson wrote: > > > On Wed, Nov 07, 2007 at 08:26:59AM -0800, Luck, Tony wrote: > > > > > Currently, XPC's heartbeat timer function runs on whatever CPU modprobe/insmod > > > > > ran on when XPC was started. To avoid the heartbeat from being delayed for > > > > > long periods the timer function must run on CPU 0. > > > > > > > > Does Altix allow hot remove of cpu0? If so, then you have a problem. > > > > > > At this time Altix does not support hot remove of cpu0, but it is something > > > currently being worked on. At the time that feature is ready then this > > > code would indeed need to be modified. In the meantime, we have an existing > > > customer in need of a fix. > > > > Kdump will run the second (crash) kernel on whatever CPU the crash > > occurs on, so its quite possible for cpu 0 not to exist in the > > second kernel. Would this be a problem for this code? > > Wouldn't that cpu appear to the new OS instance as cpu0? If so, then > it should not be an issue. No, I don't believe that it does. I can try and test this theory if it helps. Perhaps my mind is corrupted by x86 thoughts. -- Horms, California Edition