On Thu 25-04-19 08:20:28, Du, Fan wrote: > > > >-----Original Message----- > >From: owner-linux...@kvack.org [mailto:owner-linux...@kvack.org] On > >Behalf Of Michal Hocko > >Sent: Thursday, April 25, 2019 4:10 PM > >To: Du, Fan <fan...@intel.com> > >Cc: a...@linux-foundation.org; Wu, Fengguang <fengguang...@intel.com>; > >Williams, Dan J <dan.j.willi...@intel.com>; Hansen, Dave > ><dave.han...@intel.com>; xishi.qiuxi...@alibaba-inc.com; Huang, Ying > ><ying.hu...@intel.com>; linux...@kvack.org; linux-kernel@vger.kernel.org > >Subject: Re: [RFC PATCH 5/5] mm, page_alloc: Introduce > >ZONELIST_FALLBACK_SAME_TYPE fallback list > > > >On Thu 25-04-19 07:55:58, Du, Fan wrote: > >> >> PMEM is good for frequently read accessed page, e.g. page cache(implicit > >> >> page > >> >> request), or user space data base (explicit page request) > >> >> For now this patch create GFP_SAME_NODE_TYPE for such cases, > >additional > >> >> Implementation will be followed up. > >> > > >> >Then simply configure that NUMA node as movable and you get these > >> >allocations for any movable allocation. I am not really convinced a new > >> >gfp flag is really justified. > >> > >> Case 1: frequently write and/or read accessed page deserved to DRAM > > > >NUMA balancing > > Sorry, I mean page cache case here. > Numa balancing works for pages mapped in pagetable style.
I would still expect that a remote PMEM node access latency is smaller/comparable to the real storage so a promoting part is not that important for the unmapped pagecache. Maybe I am wrong here but that really begs for some experiments before we start adding special casing. -- Michal Hocko SUSE Labs
