On 20-06-24 22:07:50, Michal Hocko wrote: > On Wed 24-06-20 13:01:40, Ben Widawsky wrote: > > On 20-06-24 21:51:58, Michal Hocko wrote: > > > On Wed 24-06-20 12:37:33, Ben Widawsky wrote: > > > > On 20-06-24 20:39:17, Michal Hocko wrote: > > > > > On Wed 24-06-20 09:16:43, Ben Widawsky wrote: > [...] > > > > > > > Or do I miss something that really requires more involved approach like > > > > > > > building custom zonelists and other larger changes to the allocator? > > > > > > > > > > > > I think I'm missing how this allows selecting from multiple preferred nodes. In > > > > > > this case when you try to get the page from the freelist, you'll get the > > > > > > zonelist of the preferred node, and when you actually scan through on page > > > > > > allocation, you have no way to filter out the non-preferred nodes. I think the > > > > > > plumbing of multiple nodes has to go all the way through > > > > > > __alloc_pages_nodemask(). But it's possible I've missed the point. > > > > > > > > > > policy_nodemask() will provide the nodemask which will be used as a > > > > > filter on the policy_node. > > > > > > > > Ah, gotcha. Enabling independent masks seemed useful. Some bad decisions got me > > > > to that point. UAPI cannot get independent masks, and callers of these functions > > > > don't yet use them. > > > > > > > > So let me ask before I actually type it up and find it's much much simpler, is > > > > there not some perceived benefit to having both masks being independent? > > > > > > I am not sure I follow. Which two masks do you have in mind? zonelist > > > and user provided nodemask? > > > > Internally, a nodemask_t for preferred node, and a nodemask_t for bound nodes. > > Each mask is a local to its policy object. I mean for __alloc_pages_nodemask as an internal API. That is irrespective of policy. Policy decisions are all made beforehand. The question from a few mails ago was whether there is any use in keeping that change to __alloc_pages_nodemask accepting two nodemasks.
