![]() | |||||||||||||
Messages in this thread |
Tim Hockin wrote: >On Tue, Jan 20, 2004 at 06:45:37PM +1100, Nick Piggin wrote: > >>>I guess a hotplug script MAY fail. I don't think it's a good idea to make >>>your CPU hotplug script fail. May and Misght are different. It's up to >>>the >>>implementor whether the script can get into a failure condition. >>> >>> >>Sorry bad wording. The script may fail to be executed. >> > >Under what conditions? Not arbitrary entropy, surely. If a hotplug script >is present and does not blow up, it should be safe to assume it will be run >upon an event being delivered. If not, we have a WAY bigger problem :) > That assumption is not safe. The main problems are of course process limits and memory allocation failure. > >>>What if <which> process needs guaranteed scheduling latency? Do we really >>>_guarantee_ scheduling latency *anywhere*? >>> >>We do guarantee that a realtime task won't be blocked waiting for >>a hotplug script to fault in and start it up again (which may not >>happen). Not sure how important this issue is. >> > >We have a conflict of priority here. If an RT task is affined to CPU A and >CPU A gets yanked out, what do we do? > >Obviously the RT task can't keep running as it was. It was affined to A. >Maybe for a good reason. I see we have a few choices here: > >* re-affine it automatically, thereby silently undoing the explicit > affinity. >* violate it's RT scheduling by not running it until it has been re-affined > or CPU A returns to the pool/ > >Sending it a SIGPWR means you have to run it on a different CPU that it was >affined to, which is already a violation. > At least the task has the option to handle the problem. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||||
| Last update: 2005-03-22 14:00 [from the cache] ©2003-2008 | |||||||||||||