From 119e9db233ad0f4cbd4cfb9f9385a7bca378b37d Mon Sep 17 00:00:00 2001 From: Zeng Chi Date: Mon, 21 Sep 2026 18:24:42 +0800 Subject: KVM: Don't pre-reserve xarray entries when storing empty/NULL attributes Skip the xarray reservation loop when clearing all memory attributes, as storing NULL only erases the entry and never needs to allocate, so no reservation (and no cleanup of a failed one) is required in that case. Suggested-by: Sean Christopherson Cc: David Ballesteros Signed-off-by: Zeng Chi Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com [sean: split to separate patch] Signed-off-by: Sean Christopherson --- tools/testing/radix-tree/benchmark.c | 150 +++++++++++++++++++++++++++++++++++ 1 file changed, 150 insertions(+) create mode 100644 tools/testing/radix-tree/benchmark.c (limited to 'tools/testing/radix-tree/benchmark.c') diff --git a/tools/testing/radix-tree/benchmark.c b/tools/testing/radix-tree/benchmark.c new file mode 100644 index 000000000..523c79f22 --- /dev/null +++ b/tools/testing/radix-tree/benchmark.c @@ -0,0 +1,150 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * benchmark.c: + * Author: Konstantin Khlebnikov + */ +#include +#include +#include +#include +#include "test.h" + +#define NSEC_PER_SEC 1000000000L + +static long long benchmark_iter(struct radix_tree_root *root, bool tagged) +{ + volatile unsigned long sink = 0; + struct radix_tree_iter iter; + struct timespec start, finish; + long long nsec; + int l, loops = 1; + void **slot; + +#ifdef BENCHMARK +again: +#endif + clock_gettime(CLOCK_MONOTONIC, &start); + for (l = 0; l < loops; l++) { + if (tagged) { + radix_tree_for_each_tagged(slot, root, &iter, 0, 0) + sink ^= (unsigned long)slot; + } else { + radix_tree_for_each_slot(slot, root, &iter, 0) + sink ^= (unsigned long)slot; + } + } + clock_gettime(CLOCK_MONOTONIC, &finish); + + nsec = (finish.tv_sec - start.tv_sec) * NSEC_PER_SEC + + (finish.tv_nsec - start.tv_nsec); + +#ifdef BENCHMARK + if (loops == 1 && nsec * 5 < NSEC_PER_SEC) { + loops = NSEC_PER_SEC / nsec / 4 + 1; + goto again; + } +#endif + + nsec /= loops; + return nsec; +} + +static void benchmark_insert(struct radix_tree_root *root, + unsigned long size, unsigned long step) +{ + struct timespec start, finish; + unsigned long index; + long long nsec; + + clock_gettime(CLOCK_MONOTONIC, &start); + + for (index = 0 ; index < size ; index += step) + item_insert(root, index); + + clock_gettime(CLOCK_MONOTONIC, &finish); + + nsec = (finish.tv_sec - start.tv_sec) * NSEC_PER_SEC + + (finish.tv_nsec - start.tv_nsec); + + printv(2, "Size: %8ld, step: %8ld, insertion: %15lld ns\n", + size, step, nsec); +} + +static void benchmark_tagging(struct radix_tree_root *root, + unsigned long size, unsigned long step) +{ + struct timespec start, finish; + unsigned long index; + long long nsec; + + clock_gettime(CLOCK_MONOTONIC, &start); + + for (index = 0 ; index < size ; index += step) + radix_tree_tag_set(root, index, 0); + + clock_gettime(CLOCK_MONOTONIC, &finish); + + nsec = (finish.tv_sec - start.tv_sec) * NSEC_PER_SEC + + (finish.tv_nsec - start.tv_nsec); + + printv(2, "Size: %8ld, step: %8ld, tagging: %17lld ns\n", + size, step, nsec); +} + +static void benchmark_delete(struct radix_tree_root *root, + unsigned long size, unsigned long step) +{ + struct timespec start, finish; + unsigned long index; + long long nsec; + + clock_gettime(CLOCK_MONOTONIC, &start); + + for (index = 0 ; index < size ; index += step) + item_delete(root, index); + + clock_gettime(CLOCK_MONOTONIC, &finish); + + nsec = (finish.tv_sec - start.tv_sec) * NSEC_PER_SEC + + (finish.tv_nsec - start.tv_nsec); + + printv(2, "Size: %8ld, step: %8ld, deletion: %16lld ns\n", + size, step, nsec); +} + +static void benchmark_size(unsigned long size, unsigned long step) +{ + RADIX_TREE(tree, GFP_KERNEL); + long long normal, tagged; + + benchmark_insert(&tree, size, step); + benchmark_tagging(&tree, size, step); + + tagged = benchmark_iter(&tree, true); + normal = benchmark_iter(&tree, false); + + printv(2, "Size: %8ld, step: %8ld, tagged iteration: %8lld ns\n", + size, step, tagged); + printv(2, "Size: %8ld, step: %8ld, normal iteration: %8lld ns\n", + size, step, normal); + + benchmark_delete(&tree, size, step); + + item_kill_tree(&tree); + rcu_barrier(); +} + +void benchmark(void) +{ + unsigned long size[] = {1 << 10, 1 << 20, 0}; + unsigned long step[] = {1, 2, 7, 15, 63, 64, 65, + 128, 256, 512, 12345, 0}; + int c, s; + + printv(1, "starting benchmarks\n"); + printv(1, "RADIX_TREE_MAP_SHIFT = %d\n", RADIX_TREE_MAP_SHIFT); + + for (c = 0; size[c]; c++) + for (s = 0; step[s]; s++) + benchmark_size(size[c], step[s]); +} -- cgit v1.3.1