This is a prototype series that introduces a bulk order-0 page allocator with sunrpc being the first user. The implementation is not particularly efficient and the intention is to iron out what the semantics of the API should be. That said, sunrpc was reported to have reduced allocation latency when refilling a pool. As a side-note, while the implementation could be more efficient, it would require fairly deep surgery in numerous places. The lock scope would need to be significantly reduced, particularly as vmstat, per-cpu and the buddy allocator have different locking protocol that overal -- e.g. all partially depend on irqs being disabled at various points. Secondly, the core of the allocator deals with single pages where as both the bulk allocator and per-cpu allocator operate in batches. All of that has to be reconciled with all the existing users and their constraints (memory offline, CMA and cpusets being the trickiest). In terms of semantics required by new users, my preference is that a pair of patches be applied -- the first which adds the required semantic to the bulk allocator and the second which adds the new user. Patch 1 of this series is a cleanup to sunrpc, it could be merged separately but is included here for convenience. Patch 2 is the prototype bulk allocator Patch 3 is the sunrpc user. Chuck also has a patch which further caches pages but is not included in this series. It's not directly related to the bulk allocator and as it caches pages, it might have other concerns (e.g. does it need a shrinker?) This has only been lightly tested on a low-end NFS server. It did not break but would benefit from an evaluation to see how much, if any, the headline performance changes. The biggest concern is that a light test case showed that there are a *lot* of bulk requests for 1 page which gets delegated to the normal allocator. The same criteria should apply to any other users. include/linux/gfp.h | 13 +++++ mm/page_alloc.c | 113 +++++++++++++++++++++++++++++++++++++++++- net/sunrpc/svc_xprt.c | 47 ++++++++++++------ 3 files changed, 157 insertions(+), 16 deletions(-) -- 2.26.2
