On Thu, Apr 04, 2013 at 06:20:23PM +0200, Michal Hocko wrote: >On Thu 04-04-13 18:17:46, Michal Hocko wrote: >> On Thu 04-04-13 17:09:08, Wanpeng Li wrote: >> > order >= MAX_ORDER pages are only allocated at boot stage using the >> > bootmem allocator with the "hugepages=xxx" option. These pages are never >> > free after boot by default since it would be a one-way street(>= MAX_ORDER >> > pages cannot be allocated later), but if administrator confirm not to >> > use these gigantic pages any more, these pinned pages will waste memory >> > since other users can't grab free pages from gigantic hugetlb pool even >> > if OOM, it's not flexible. The patchset add hugetlb gigantic page pools >> > shrink supporting. Administrator can enable knob exported in sysctl to >> > permit to shrink gigantic hugetlb pool. >> >> I am not sure I see why the new knob is needed. >> /sys/kernel/mm/hugepages/hugepages-*/nr_hugepages is root interface so >> an additional step to allow writing to the file doesn't make much sense >> to me to be honest. >> >> Support for shrinking gigantic huge pages makes some sense to me but I >> would be interested in the real world example. GB pages are usually used >> in very specific environments where the amount is usually well known. >> >> I could imagine nr_hugepages_mempolicy would make more sense to free >> pages from particular nodes so they could be offlined for example. >> Does the patchset handles this as well? > >Ohh, I should have checked before asking. Both knobs use the same >hugetlb_sysctl_handler_common and unless there is something hardcoded in >the patches then it should be supproted. I'm very happy if you can review this patchset in details, any comments are welcome. ;-) Regards, Wanpeng Li > >-- >Michal Hocko >SUSE Labs > >-- >To unsubscribe, send a message with 'unsubscribe linux-mm' in >the body to majordomo@xxxxxxxxx. For more info on Linux MM, >see: http://www.linux-mm.org/ . >Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a> -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>