From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT, USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 86D86C2BA83 for ; Fri, 14 Feb 2020 07:51:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 42396222C4 for ; Fri, 14 Feb 2020 07:51:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="ITedSQx3" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728968AbgBNHvu (ORCPT ); Fri, 14 Feb 2020 02:51:50 -0500 Received: from mail-pg1-f202.google.com ([209.85.215.202]:53356 "EHLO mail-pg1-f202.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726004AbgBNHvr (ORCPT ); Fri, 14 Feb 2020 02:51:47 -0500 Received: by mail-pg1-f202.google.com with SMTP id t17so5563266pgb.20 for ; Thu, 13 Feb 2020 23:51:46 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=AeARklAI4wkNnAg/cGpZSPjuAHJ+hARasiCvJQxYyEo=; b=ITedSQx3bjIWH4nXDwgVKm1eJgwuab4E0XttrqPIUoOyNH3bdU8AlBmDK1X4oCPzsr kpGm/86Q/Mt1cFjGcIpnsan+4qoV0pscbr6CboesGK8IcjGBdfubvwKmFCbv17TiYIpS 96CbMNXT3y+RehwPCQBEITtimRJgCTjd6xHhNvsPgUv3AC5AGMI/DchbBqQH9v1t/N5g P5qJIssNRl5Hch7lyTv51VzmTKFLxVhMKyhY4EX0s4VKLqhxqcZrDsRrddygY/08orHh taD4Zfl5jUDxpvU0phLQ4/q5ZoajdSn+42xgCryPy87Vd7GH/p753Xq/lT51Bm9hrypQ z2uQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=AeARklAI4wkNnAg/cGpZSPjuAHJ+hARasiCvJQxYyEo=; b=DJDvLOCdk4Qrf2zNkWz+dNkFmXnJplwJ1EPCNzNTlJbE4Uv+2+smW1YHZfv3XslP3A 3duS+UYEqadHNyfX9gD4/41iqElSomeH3k+2ZX6JUfpFiZpE3sTLX29rNI+YglrHHUBG +lYgVgBWDHxoEYfE5125y4V3EI4R1D2GOFc9T27pTgiEglsCPLnpVlVg3relFrD/nYsQ TMopoefZUeHfD7fT05asZhxcHl41eU/FcwHKzURakopw6CIac5CQJgCYVXfYHXukOdq5 3qXu91xtljl+S4op+etZe4F8BBS4PTt0yAe2q0N1C/05ngrBjzA+B3xZRnPqo2j4aTDu e2YA== X-Gm-Message-State: APjAAAWShOyrJEqQkXFc9ufR1QkQMMrk86kC2DOoTRGgb23oUOY/BmVk xBbeIfVbpUzJQepdTWrShjmwCnFxIc+E X-Google-Smtp-Source: APXvYqwVhzRGG2q8qg7PEz9pWpjQnDjfjNro/7O0bnlMq1jPSU8YBFDkAh7s5g2wDD1rDZwkBxNVLhv+np9x X-Received: by 2002:a63:705e:: with SMTP id a30mr2067907pgn.182.1581666706043; Thu, 13 Feb 2020 23:51:46 -0800 (PST) Date: Thu, 13 Feb 2020 23:51:29 -0800 In-Reply-To: <20200214075133.181299-1-irogers@google.com> Message-Id: <20200214075133.181299-3-irogers@google.com> Mime-Version: 1.0 References: <20191206231539.227585-1-irogers@google.com> <20200214075133.181299-1-irogers@google.com> X-Mailer: git-send-email 2.25.0.265.gbab2e86ba0-goog Subject: [PATCH v6 2/6] lib: introduce generic min-heap From: Ian Rogers To: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Andrew Morton , Randy Dunlap , Masahiro Yamada , Shuah Khan , Krzysztof Kozlowski , Kees Cook , "Paul E. McKenney" , Masami Hiramatsu , Marco Elver , Kent Overstreet , Andy Shevchenko , Ard Biesheuvel , Gary Hook , Kan Liang , linux-kernel@vger.kernel.org Cc: Stephane Eranian , Andi Kleen , Ian Rogers Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Supports push, pop and converting an array into a heap. If the sense of the compare function is inverted then it can provide a max-heap. Based-on-work-by: Peter Zijlstra (Intel) Signed-off-by: Ian Rogers --- include/linux/min_heap.h | 135 +++++++++++++++++++++++++++ lib/Kconfig.debug | 10 ++ lib/Makefile | 1 + lib/test_min_heap.c | 194 +++++++++++++++++++++++++++++++++++++++ 4 files changed, 340 insertions(+) create mode 100644 include/linux/min_heap.h create mode 100644 lib/test_min_heap.c diff --git a/include/linux/min_heap.h b/include/linux/min_heap.h new file mode 100644 index 000000000000..0f04f49c0779 --- /dev/null +++ b/include/linux/min_heap.h @@ -0,0 +1,135 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_MIN_HEAP_H +#define _LINUX_MIN_HEAP_H + +#include +#include +#include + +/** + * struct min_heap - Data structure to hold a min-heap. + * @data: Start of array holding the heap elements. + * @size: Number of elements currently in the heap. + * @cap: Maximum number of elements that can be held in current storage. + */ +struct min_heap { + void *data; + int size; + int cap; +}; + +/** + * struct min_heap_callbacks - Data/functions to customise the min_heap. + * @elem_size: The size of each element in bytes. + * @cmp: Partial order function for this heap 'less'/'<' for min-heap, + * 'greater'/'>' for max-heap. + * @swp: Swap elements function. + */ +struct min_heap_callbacks { + int elem_size; + bool (*cmp)(const void *lhs, const void *rhs); + void (*swp)(void *lhs, void *rhs); +}; + +/* Sift the element at pos down the heap. */ +static __always_inline +void min_heapify(struct min_heap *heap, int pos, + const struct min_heap_callbacks *func) +{ + void *left_child, *right_child, *parent, *large_or_smallest; + u8 *data = (u8 *)heap->data; + + for (;;) { + if (pos * 2 + 1 >= heap->size) + break; + + left_child = data + ((pos * 2 + 1) * func->elem_size); + parent = data + (pos * func->elem_size); + large_or_smallest = parent; + if (func->cmp(left_child, large_or_smallest)) + large_or_smallest = left_child; + + if (pos * 2 + 2 < heap->size) { + right_child = data + ((pos * 2 + 2) * func->elem_size); + if (func->cmp(right_child, large_or_smallest)) + large_or_smallest = right_child; + } + if (large_or_smallest == parent) + break; + func->swp(large_or_smallest, parent); + if (large_or_smallest == left_child) + pos = (pos * 2) + 1; + else + pos = (pos * 2) + 2; + } +} + +/* Floyd's approach to heapification that is O(size). */ +static __always_inline +void min_heapify_all(struct min_heap *heap, + const struct min_heap_callbacks *func) +{ + int i; + + for (i = heap->size / 2; i >= 0; i--) + min_heapify(heap, i, func); +} + +/* Remove minimum element from the heap, O(log2(size)). */ +static __always_inline +void min_heap_pop(struct min_heap *heap, + const struct min_heap_callbacks *func) +{ + u8 *data = (u8 *)heap->data; + + if (WARN_ONCE(heap->size <= 0, "Popping an empty heap")) + return; + + /* Place last element at the root (position 0) and then sift down. */ + heap->size--; + memcpy(data, data + (heap->size * func->elem_size), func->elem_size); + min_heapify(heap, 0, func); +} + +/* + * Remove the minimum element and then push the given element. The + * implementation performs 1 sift (O(log2(size))) and is therefore more + * efficient than a pop followed by a push that does 2. + */ +static __always_inline +void min_heap_pop_push(struct min_heap *heap, + const void *element, + const struct min_heap_callbacks *func) +{ + memcpy(heap->data, element, func->elem_size); + min_heapify(heap, 0, func); +} + +/* Push an element on to the heap, O(log2(size)). */ +static __always_inline +void min_heap_push(struct min_heap *heap, const void *element, + const struct min_heap_callbacks *func) +{ + void *child, *parent; + int pos; + u8 *data = (u8 *)heap->data; + + if (WARN_ONCE(heap->size >= heap->cap, "Pushing on a full heap")) + return; + + /* Place at the end of data. */ + pos = heap->size; + memcpy(data + (pos * func->elem_size), element, func->elem_size); + heap->size++; + + /* Sift child at pos up. */ + for (; pos > 0; pos = (pos - 1) / 2) { + child = data + (pos * func->elem_size); + parent = data + ((pos - 1) / 2) * func->elem_size; + if (func->cmp(parent, child)) + break; + func->swp(parent, child); + } +} + +#endif /* _LINUX_MIN_HEAP_H */ diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 1458505192cd..e61e7fee9364 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -1771,6 +1771,16 @@ config TEST_LIST_SORT If unsure, say N. +config TEST_MIN_HEAP + tristate "Min heap test" + depends on DEBUG_KERNEL || m + help + Enable this to turn on min heap function tests. This test is + executed only once during system boot (so affects only boot time), + or at module load time. + + If unsure, say N. + config TEST_SORT tristate "Array-based sort test" depends on DEBUG_KERNEL || m diff --git a/lib/Makefile b/lib/Makefile index f19b85c87fda..171a6d7874a9 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -70,6 +70,7 @@ CFLAGS_test_ubsan.o += $(call cc-disable-warning, vla) UBSAN_SANITIZE_test_ubsan.o := y obj-$(CONFIG_TEST_KSTRTOX) += test-kstrtox.o obj-$(CONFIG_TEST_LIST_SORT) += test_list_sort.o +obj-$(CONFIG_TEST_MIN_HEAP) += test_min_heap.o obj-$(CONFIG_TEST_LKM) += test_module.o obj-$(CONFIG_TEST_VMALLOC) += test_vmalloc.o obj-$(CONFIG_TEST_OVERFLOW) += test_overflow.o diff --git a/lib/test_min_heap.c b/lib/test_min_heap.c new file mode 100644 index 000000000000..0f06d1f757b5 --- /dev/null +++ b/lib/test_min_heap.c @@ -0,0 +1,194 @@ +// SPDX-License-Identifier: GPL-2.0-only +#define pr_fmt(fmt) "min_heap_test: " fmt + +/* + * Test cases for the min max heap. + */ + +#include +#include +#include +#include +#include + +static __init bool less_than(const void *lhs, const void *rhs) +{ + return *(int *)lhs < *(int *)rhs; +} + +static __init bool greater_than(const void *lhs, const void *rhs) +{ + return *(int *)lhs > *(int *)rhs; +} + +static __init void swap_ints(void *lhs, void *rhs) +{ + int temp = *(int *)lhs; + + *(int *)lhs = *(int *)rhs; + *(int *)rhs = temp; +} + +static __init int pop_verify_heap(bool min_heap, + struct min_heap *heap, + const struct min_heap_callbacks *funcs) +{ + int last; + int *values = (int *)heap->data; + int err = 0; + + last = values[0]; + min_heap_pop(heap, funcs); + while (heap->size > 0) { + if (min_heap) { + if (last > values[0]) { + pr_err("error: expected %d <= %d\n", last, + values[0]); + err++; + } + } else { + if (last < values[0]) { + pr_err("error: expected %d >= %d\n", last, + values[0]); + err++; + } + } + last = values[0]; + min_heap_pop(heap, funcs); + } + return err; +} + +static __init int test_heapify_all(bool min_heap) +{ + int values[] = { 3, 1, 2, 4, 0x8000000, 0x7FFFFFF, 0, + -3, -1, -2, -4, 0x8000000, 0x7FFFFFF }; + struct min_heap heap = { + .data = values, + .size = ARRAY_SIZE(values), + .cap = ARRAY_SIZE(values), + }; + struct min_heap_callbacks funcs = { + .elem_size = sizeof(int), + .cmp = min_heap ? less_than : greater_than, + .swp = swap_ints, + }; + int i, err; + + /* Test with known set of values. */ + min_heapify_all(&heap, &funcs); + err = pop_verify_heap(min_heap, &heap, &funcs); + + + /* Test with randomly generated values. */ + heap.size = ARRAY_SIZE(values); + for (i = 0; i < heap.size; i++) + values[i] = get_random_int(); + + min_heapify_all(&heap, &funcs); + err += pop_verify_heap(min_heap, &heap, &funcs); + + return err; +} + +static __init int test_heap_push(bool min_heap) +{ + const int data[] = { 3, 1, 2, 4, 0x80000000, 0x7FFFFFFF, 0, + -3, -1, -2, -4, 0x80000000, 0x7FFFFFFF }; + int values[ARRAY_SIZE(data)]; + struct min_heap heap = { + .data = values, + .size = 0, + .cap = ARRAY_SIZE(values), + }; + struct min_heap_callbacks funcs = { + .elem_size = sizeof(int), + .cmp = min_heap ? less_than : greater_than, + .swp = swap_ints, + }; + int i, temp, err; + + /* Test with known set of values copied from data. */ + for (i = 0; i < ARRAY_SIZE(data); i++) + min_heap_push(&heap, &data[i], &funcs); + + err = pop_verify_heap(min_heap, &heap, &funcs); + + /* Test with randomly generated values. */ + while (heap.size < heap.cap) { + temp = get_random_int(); + min_heap_push(&heap, &temp, &funcs); + } + err += pop_verify_heap(min_heap, &heap, &funcs); + + return err; +} + +static __init int test_heap_pop_push(bool min_heap) +{ + const int data[] = { 3, 1, 2, 4, 0x80000000, 0x7FFFFFFF, 0, + -3, -1, -2, -4, 0x80000000, 0x7FFFFFFF }; + int values[ARRAY_SIZE(data)]; + struct min_heap heap = { + .data = values, + .size = 0, + .cap = ARRAY_SIZE(values), + }; + struct min_heap_callbacks funcs = { + .elem_size = sizeof(int), + .cmp = min_heap ? less_than : greater_than, + .swp = swap_ints, + }; + int i, temp, err; + + /* Fill values with data to pop and replace. */ + temp = min_heap ? 0x80000000 : 0x7FFFFFFF; + for (i = 0; i < ARRAY_SIZE(data); i++) + min_heap_push(&heap, &temp, &funcs); + + /* Test with known set of values copied from data. */ + for (i = 0; i < ARRAY_SIZE(data); i++) + min_heap_pop_push(&heap, &data[i], &funcs); + + err = pop_verify_heap(min_heap, &heap, &funcs); + + heap.size = 0; + for (i = 0; i < ARRAY_SIZE(data); i++) + min_heap_push(&heap, &temp, &funcs); + + /* Test with randomly generated values. */ + for (i = 0; i < ARRAY_SIZE(data); i++) { + temp = get_random_int(); + min_heap_pop_push(&heap, &temp, &funcs); + } + err += pop_verify_heap(min_heap, &heap, &funcs); + + return err; +} + +static int __init test_min_heap_init(void) +{ + int err = 0; + + err += test_heapify_all(true); + err += test_heapify_all(false); + err += test_heap_push(true); + err += test_heap_push(false); + err += test_heap_pop_push(true); + err += test_heap_pop_push(false); + if (err) { + pr_err("test failed with %d errors\n", err); + return -EINVAL; + } + pr_info("test passed\n"); + return 0; +} +module_init(test_min_heap_init); + +static void __exit test_min_heap_exit(void) +{ + /* do nothing */ +} +module_exit(test_min_heap_exit); + +MODULE_LICENSE("GPL"); -- 2.25.0.265.gbab2e86ba0-goog