On 17.03.20 12:01, Michal Hocko wrote: > On Tue 17-03-20 11:49:42, David Hildenbrand wrote: >> For now, distributions implement advanced udev rules to essentially >> - Don't online any hotplugged memory (s390x) >> - Online all memory to ZONE_NORMAL (e.g., most virt environments like >> hyperv) >> - Online all memory to ZONE_MOVABLE in case the zone imbalance is taken >> care of (e.g., bare metal, special virt environments) >> >> In summary: All memory is usually onlined the same way, however, the >> kernel always has to ask user space to come up with the same answer. >> E.g., Hyper-V always waits for a memory block to get onlined before >> continuing, otherwise it might end up adding memory faster than >> hotplugging it, which can result in strange OOM situations. This waiting >> slows down adding of a bigger amount of memory. >> >> Let's allow to specify a default online_type, not just "online" and >> "offline". This allows distributions to configure the default online_type >> when booting up and be done with it. >> >> We can now specify "offline", "online", "online_movable" and >> "online_kernel" via >> - "memhp_default_state=" on the kernel cmdline >> - /sys/devices/system/memory/auto_online_blocks >> just like we are able to specify for a single memory block via >> /sys/devices/system/memory/memoryX/state >> >> Reviewed-by: Wei Yang <richard.weiyang@xxxxxxxxx> >> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> >> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> >> Cc: Michal Hocko <mhocko@xxxxxxxxxx> >> Cc: Oscar Salvador <osalvador@xxxxxxx> >> Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx> >> Cc: Baoquan He <bhe@xxxxxxxxxx> >> Cc: Wei Yang <richard.weiyang@xxxxxxxxx> >> Signed-off-by: David Hildenbrand <david@xxxxxxxxxx> > > As I've said earlier and several times already, I really dislike this > interface. But it is fact that this patch doesn't make it any worse. > Quite contrary, so feel free to add > Acked-by: Michal Hocko <mhocko@xxxxxxxx> Thanks Michal! -- Thanks, David / dhildenb
