Hi Peng, On 6/5/23 11:28, Peng Zhang wrote: > > > 在 2023/6/2 16:10, Yin, Fengwei 写道: >> Hi Liam, >> >> On 6/1/2023 10:15 AM, Liam R. Howlett wrote: >>> Initial work on preallocations showed no regression in performance >>> during testing, but recently some users (both on [1] and off [android] >>> list) have reported that preallocating the worst-case number of nodes >>> has caused some slow down. This patch set addresses the number of >>> allocations in a few ways. >>> >>> During munmap() most munmap() operations will remove a single VMA, so >>> leverage the fact that the maple tree can place a single pointer at >>> range 0 - 0 without allocating. This is done by changing the index in >>> the 'sidetree'. >>> >>> Re-introduce the entry argument to mas_preallocate() so that a more >>> intelligent guess of the node count can be made. >>> >>> Patches are in the following order: >>> 0001-0002: Testing framework for benchmarking some operations >>> 0003-0004: Reduction of maple node allocation in sidetree >>> 0005: Small cleanup of do_vmi_align_munmap() >>> 0006-0013: mas_preallocate() calculation change >>> 0014: Change the vma iterator order >> I did run The AIM:page_test on an IceLake 48C/96T + 192G RAM platform with >> this patchset. >> >> The result has a little bit improvement: >> Base (next-20230602): >> 503880 >> Base with this patchset: >> 519501 >> >> But they are far from the none-regression result (commit 7be1c1a3c7b1): >> 718080 >> >> >> Some other information I collected: >> With Base, the mas_alloc_nodes are always hit with request: 7. >> With this patchset, the request are 1 or 5. >> >> I suppose this is the reason for improvement from 503880 to 519501. >> >> With commit 7be1c1a3c7b1, mas_store_gfp() in do_brk_flags never triggered >> mas_alloc_nodes() call. Thanks. > Hi Fengwei, > > I think it may be related to the inaccurate number of nodes allocated > in the pre-allocation. I slightly modified the pre-allocation in this > patchset, but I don't know if it works. It would be great if you could > help test it, and help pinpoint the cause. Below is the diff, which can > be applied based on this pachset. I tried the patch, it could eliminate the call of mas_alloc_nodes() during the test. But the result of benchmark got a little bit improvement: 529040 But it's still much less than none-regression result. I will also double confirm the none-regression result. Regards Yin, Fengwei > > Thanks, > Peng > > diff --git a/lib/maple_tree.c b/lib/maple_tree.c > index 5ea211c3f186..e67bf2744384 100644 > --- a/lib/maple_tree.c > +++ b/lib/maple_tree.c > @@ -5575,9 +5575,11 @@ int mas_preallocate(struct ma_state *mas, void *entry, gfp_t gfp) > goto ask_now; > } > > - /* New root needs a singe node */ > - if (unlikely(mte_is_root(mas->node))) > - goto ask_now; > + if ((node_size == wr_mas.node_end + 1 && > + mas->offset == wr_mas.node_end) || > + (node_size == wr_mas.node_end && > + wr_mas.offset_end - mas->offset == 1)) > + return 0; > > /* Potential spanning rebalance collapsing a node, use worst-case */ > if (node_size - 1 <= mt_min_slots[wr_mas.type]) > @@ -5590,7 +5592,6 @@ int mas_preallocate(struct ma_state *mas, void *entry, gfp_t gfp) > if (likely(!mas_is_err(mas))) > return 0; > > - mas_set_alloc_req(mas, 0); > ret = xa_err(mas->node); > mas_reset(mas); > mas_destroy(mas); > > >> >> >> Regards >> Yin, Fengwei >> >>> >>> [1] https://lore.kernel.org/linux-mm/202305061457.ac15990c-yujie.liu@xxxxxxxxx/ >>> >>> Liam R. Howlett (14): >>> maple_tree: Add benchmarking for mas_for_each >>> maple_tree: Add benchmarking for mas_prev() >>> mm: Move unmap_vmas() declaration to internal header >>> mm: Change do_vmi_align_munmap() side tree index >>> mm: Remove prev check from do_vmi_align_munmap() >>> maple_tree: Introduce __mas_set_range() >>> mm: Remove re-walk from mmap_region() >>> maple_tree: Re-introduce entry to mas_preallocate() arguments >>> mm: Use vma_iter_clear_gfp() in nommu >>> mm: Set up vma iterator for vma_iter_prealloc() calls >>> maple_tree: Move mas_wr_end_piv() below mas_wr_extend_null() >>> maple_tree: Update mas_preallocate() testing >>> maple_tree: Refine mas_preallocate() node calculations >>> mm/mmap: Change vma iteration order in do_vmi_align_munmap() >>> >>> fs/exec.c | 1 + >>> include/linux/maple_tree.h | 23 ++++- >>> include/linux/mm.h | 4 - >>> lib/maple_tree.c | 78 ++++++++++---- >>> lib/test_maple_tree.c | 74 +++++++++++++ >>> mm/internal.h | 40 ++++++-- >>> mm/memory.c | 16 ++- >>> mm/mmap.c | 171 ++++++++++++++++--------------- >>> mm/nommu.c | 45 ++++---- >>> tools/testing/radix-tree/maple.c | 59 ++++++----- >>> 10 files changed, 331 insertions(+), 180 deletions(-) >>>
