On Mon, 3 Mar 2008, Maxim Sobolev wrote:
Cool! I am just curious if the new topology code is flexible enough to support cores that come and go on the fly? This could be useful in several scenarios, such as for example when running under multi-core aware hypervisor (e.g. Niagara), in the cases when pro-active power manager shuts down some cores to conserve power, in server applications when one of CPUs either has fried or has been unplugged, etc.
We have quite a bit of kernel code that expects CPUs never come and go; I've been hoping to interest people in having a devsummit session on CPU hotplugging for a couple of years now. :-) I don't see physical hotplugging as all that motivating currently, by hypervisor reallocation of CPUs *is* immediately motivating. You'll find assumptions of fixed CPUs all over our kernel -- schedulers, memory allocators, timer management, etc. A mature model for starting and stopping CPUs and allowing kernel subsystems to register with event handlers in order to start/stop their own services is necessary. Similarly, providing a way for user applications that care about CPU placement to hook into the event stream and respond appropriately is important.
Robert N M Watson Computer Laboratory University of Cambridge _______________________________________________ [email protected] mailing list http://lists.freebsd.org/mailman/listinfo/cvs-all To unsubscribe, send any mail to "[EMAIL PROTECTED]"
