On Tue 26-02-19 13:47:37, Pingfan Liu wrote: > On Tue, Feb 26, 2019 at 12:04 AM Michal Hocko <mhocko@xxxxxxxxxx> wrote: > > > > On Sun 24-02-19 20:34:03, Pingfan Liu wrote: > > > There are NUMA machines with memory-less node. At present page allocator builds the > > > full fallback info by build_zonelists(). But memblock allocator does not utilize > > > this info. And for memory-less node, memblock allocator just falls back "node 0", > > > without utilizing the nearest node. Unfortunately, the percpu section is allocated > > > by memblock, which is accessed frequently after bootup. > > > > > > This series aims to improve the performance of per cpu section on memory-less node > > > by feeding node's fallback info to memblock allocator on x86, like we do for page > > > allocator. On other archs, it requires independent effort to setup node to cpumask > > > map ahead. > > > > Do you have any numbers to tell us how much does this improve the > > situation? > > Not yet. At present just based on the fact that we prefer to allocate > per cpu area on local node. Yes, we _usually_ do. But the additional complexity should be worth it. And if we find out that the final improvement is not all that great and considering that memory-less setups are crippled anyway then it might turn out we just do not care all that much. -- Michal Hocko SUSE Labs
