On 02/17/2010 06:38 PM, Yinghai Lu wrote: >> >> I'm confused by this one. This would seem to mean that unless you're >> specifying possible_cpus= then you are not treating anything as >> hotpluggable. >> >> This is clearly wrong, and it would appear to go the wrong direction in >> terms of what is safe. >> >> What am I missing here? > > per_cpu setup will allocate some mem for every cpu according to possible cpus. > Yes, and I have repeatedly requested that we allocate the memory on the first up of a disabled CPU rather than eagerly, but in *most* configurations the amount is relatively small. > no spec says that we should disable cpus entries in MADT as hotplug cpus. Reality seems to, though. Consider the bug report that led to patch 681ee44d40d7c93b42118320e4620d07d8704fd6 for example. > also how many system that support hotplug cpus there? In terms of physical machines, not all that many; however, it is getting common to use CPU hotplug for virtual environments so they can be dynamically scaled. -hpa -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
