From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Hansen Date: Mon, 17 May 2004 15:52:11 +0000 Subject: Re: [Lhns-devel] Re: Who's doing what with cpu/memory/node hotplug? Message-Id: <1084809130.24128.6199.camel@nighthawk> List-Id: References: <20040513150842.22F5.YGOTO@us.fujitsu.com> In-Reply-To: <20040513150842.22F5.YGOTO@us.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org On Mon, 2004-05-17 at 01:38, Matthias Fouquet-Lapar wrote: > I think I'm not quite sure why you need hotplug to balance CPUs between > partitons. (You are not moving physical components for this, right ?) Right, there is no movement of physical components. But, from Linux's perspective, it really doesn't matter. There is a cpu that I'm using, it won't be there in a minute, I better stop using it. That means that Linux has to be careful with things like the for_each_cpu(). Take a look at the calls to hotcpu_notifier() for more things that we keep an eye on when CPUs go down. That's pretty much what the CPU hotplug code does, and *that* doesn't change whether the CPUs are real or more virtualized. > > Remember, chips designs like the POWER4 tend to have a lot of cost and > > design overhead in error correction and detection that are quite absent > > from consumer type cpus. > > Taken beside which CPU architecture has best the RAS features :-), which are > CPU error types on ppc64 (besides cache SBE etc) which allow gracefully > recovery (i.e. the OS continues operating and non-affected user processes > continue to run) and hotplug replacement Sorry, I'm just a software guy. No one tells me such things :) Rusty, have I butchered explaining CPU hotplug enough for you to step in, yet? -- Dave ------------------------------------------------------- This SF.Net email is sponsored by: SourceForge.net Broadband Sign-up now for SourceForge Broadband and get the fastest 6.0/768 connection for only $19.95/mo for the first 3 months! http://ads.osdn.com/?ad_id%62&alloc_ida84&op=click _______________________________________________ Linux-hotplug-devel mailing list http://linux-hotplug.sourceforge.net Linux-hotplug-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-hotplug-devel