From 361c678be709f67a5b609ec3666ff5fec7eb8baf Mon Sep 17 00:00:00 2001 From: "Liam R. Howlett" Date: Mon, 24 Jul 2023 14:31:43 -0400 Subject: [PATCH] maple_tree: add benchmarking for mas_for_each Patch series "Reduce preallocations for maple tree", v3. 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 of the VMAs to be indexed by the count, starting at 0. Re-introduce the entry argument to mas_preallocate() so that a more intelligent guess of the node count can be made. Implement the more intelligent guess of the node count, although there is more work to be done. During development of v2 of this patch set, I also noticed that the number of nodes being allocated for a rebalance was beyond what could possibly be needed. This is addressed in patch 0008. This patch (of 15): Add a way to test the speed of mas_for_each() to the testing code. Link: https://lkml.kernel.org/r/20230724183157.3939892-1-Liam.Howlett@oracle.com Link: https://lkml.kernel.org/r/20230724183157.3939892-2-Liam.Howlett@oracle.com Signed-off-by: Liam R. Howlett Cc: Peng Zhang Cc: Suren Baghdasaryan Signed-off-by: Andrew Morton --- lib/test_maple_tree.c | 39 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+) diff --git a/lib/test_maple_tree.c b/lib/test_maple_tree.c index 3207c2107918..9c4cf5fb2b7f 100644 --- a/lib/test_maple_tree.c +++ b/lib/test_maple_tree.c @@ -44,6 +44,7 @@ atomic_t maple_tree_tests_passed; /* #define BENCH_WALK */ /* #define BENCH_MT_FOR_EACH */ /* #define BENCH_FORK */ +/* #define BENCH_MAS_FOR_EACH */ #ifdef __KERNEL__ #define mt_set_non_kernel(x) do {} while (0) @@ -1770,6 +1771,37 @@ static noinline void __init bench_mt_for_each(struct maple_tree *mt) } #endif +#if defined(BENCH_MAS_FOR_EACH) +static noinline void __init bench_mas_for_each(struct maple_tree *mt) +{ + int i, count = 1000000; + unsigned long max = 2500; + void *entry; + MA_STATE(mas, mt, 0, 0); + + for (i = 0; i < max; i += 5) { + int gap = 4; + + if (i % 30 == 0) + gap = 3; + mtree_store_range(mt, i, i + gap, xa_mk_value(i), GFP_KERNEL); + } + + rcu_read_lock(); + for (i = 0; i < count; i++) { + unsigned long j = 0; + + mas_for_each(&mas, entry, max) { + MT_BUG_ON(mt, entry != xa_mk_value(j)); + j += 5; + } + mas_set(&mas, 0); + } + rcu_read_unlock(); + +} +#endif + /* check_forking - simulate the kernel forking sequence with the tree. */ static noinline void __init check_forking(struct maple_tree *mt) { @@ -3498,6 +3530,13 @@ static int __init maple_tree_seed(void) mtree_destroy(&tree); goto skip; #endif +#if defined(BENCH_MAS_FOR_EACH) +#define BENCH + mt_init_flags(&tree, MT_FLAGS_ALLOC_RANGE); + bench_mas_for_each(&tree); + mtree_destroy(&tree); + goto skip; +#endif mt_init_flags(&tree, MT_FLAGS_ALLOC_RANGE); check_iteration(&tree);