From fc37bbb3289f61e23e3f866eeeb6c865ee4d3088 Mon Sep 17 00:00:00 2001 From: Gang Li Date: Thu, 22 Feb 2024 22:04:14 +0800 Subject: hugetlb: code clean for hugetlb_hstate_alloc_pages Patch series "hugetlb: parallelize hugetlb page init on boot", v6. Introduction ------------ Hugetlb initialization during boot takes up a considerable amount of time. For instance, on a 2TB system, initializing 1,800 1GB huge pages takes 1-2 seconds out of 10 seconds. Initializing 11,776 1GB pages on a 12TB Intel host takes more than 1 minute[1]. This is a noteworthy figure. Inspired by [2] and [3], hugetlb initialization can also be accelerated through parallelization. Kernel already has infrastructure like padata_do_multithreaded, this patch uses it to achieve effective results by minimal modifications. [1] https://lore.kernel.org/all/783f8bac-55b8-5b95-eb6a-11a583675000@google.com/ [2] https://lore.kernel.org/all/20200527173608.2885243-1-daniel.m.jordan@oracle.com/ [3] https://lore.kernel.org/all/20230906112605.2286994-1-usama.arif@bytedance.com/ [4] https://lore.kernel.org/all/76becfc1-e609-e3e8-2966-4053143170b6@google.com/ max_threads ----------- This patch use `padata_do_multithreaded` like this: ``` job.max_threads = num_node_state(N_MEMORY) * multiplier; padata_do_multithreaded(&job); ``` To fully utilize the CPU, the number of parallel threads needs to be carefully considered. `max_threads = num_node_state(N_MEMORY)` does not fully utilize the CPU, so we need to multiply it by a multiplier. Tests below indicate that a multiplier of 2 significantly improves performance, and although larger values also provide improvements, the gains are marginal. multiplier 1 2 3 4 5 ------------ ------- ------- ------- ------- ------- 256G 2node 358ms 215ms 157ms 134ms 126ms 2T 4node 979ms 679ms 543ms 489ms 481ms 50G 2node 71ms 44ms 37ms 30ms 31ms Therefore, choosing 2 as the multiplier strikes a good balance between enhancing parallel processing capabilities and maintaining efficient resource management. Test result ----------- test case no patch(ms) patched(ms) saved ------------------- -------------- ------------- -------- 256c2T(4 node) 1G 4745 2024 57.34% 128c1T(2 node) 1G 3358 1712 49.02% 12T 1G 77000 18300 76.23% 256c2T(4 node) 2M 3336 1051 68.52% 128c1T(2 node) 2M 1943 716 63.15% This patch (of 8): The readability of `hugetlb_hstate_alloc_pages` is poor. By cleaning the code, its readability can be improved, facilitating future modifications. This patch extracts two functions to reduce the complexity of `hugetlb_hstate_alloc_pages` and has no functional changes. - hugetlb_hstate_alloc_pages_node_specific() to handle iterates through each online node and performs allocation if necessary. - hugetlb_hstate_alloc_pages_report() report error during allocation. And the value of h->max_huge_pages is updated accordingly. Link: https://lkml.kernel.org/r/20240222140422.393911-1-gang.li@linux.dev Link: https://lkml.kernel.org/r/20240222140422.393911-2-gang.li@linux.dev Signed-off-by: Gang Li Tested-by: David Rientjes Reviewed-by: Muchun Song Reviewed-by: Tim Chen Cc: Daniel Jordan Cc: David Hildenbrand Cc: Jane Chu Cc: Paul E. McKenney Cc: Randy Dunlap Cc: Steffen Klassert Cc: Alexey Dobriyan Cc: Mike Kravetz Signed-off-by: Andrew Morton --- mm/hugetlb.c | 46 +++++++++++++++++++++++++++++----------------- 1 file changed, 29 insertions(+), 17 deletions(-) (limited to 'mm') diff --git a/mm/hugetlb.c b/mm/hugetlb.c index c3d68671cbae..1ee4d11e09d8 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -3482,6 +3482,33 @@ static void __init hugetlb_hstate_alloc_pages_onenode(struct hstate *h, int nid) h->max_huge_pages_node[nid] = i; } +static bool __init hugetlb_hstate_alloc_pages_specific_nodes(struct hstate *h) +{ + int i; + bool node_specific_alloc = false; + + for_each_online_node(i) { + if (h->max_huge_pages_node[i] > 0) { + hugetlb_hstate_alloc_pages_onenode(h, i); + node_specific_alloc = true; + } + } + + return node_specific_alloc; +} + +static void __init hugetlb_hstate_alloc_pages_errcheck(unsigned long allocated, struct hstate *h) +{ + if (allocated < h->max_huge_pages) { + char buf[32]; + + string_get_size(huge_page_size(h), 1, STRING_UNITS_2, buf, 32); + pr_warn("HugeTLB: allocating %lu of page size %s failed. Only allocated %lu hugepages.\n", + h->max_huge_pages, buf, allocated); + h->max_huge_pages = allocated; + } +} + /* * NOTE: this routine is called in different contexts for gigantic and * non-gigantic pages. @@ -3499,7 +3526,6 @@ static void __init hugetlb_hstate_alloc_pages(struct hstate *h) struct folio *folio; LIST_HEAD(folio_list); nodemask_t *node_alloc_noretry; - bool node_specific_alloc = false; /* skip gigantic hugepages allocation if hugetlb_cma enabled */ if (hstate_is_gigantic(h) && hugetlb_cma_size) { @@ -3508,14 +3534,7 @@ static void __init hugetlb_hstate_alloc_pages(struct hstate *h) } /* do node specific alloc */ - for_each_online_node(i) { - if (h->max_huge_pages_node[i] > 0) { - hugetlb_hstate_alloc_pages_onenode(h, i); - node_specific_alloc = true; - } - } - - if (node_specific_alloc) + if (hugetlb_hstate_alloc_pages_specific_nodes(h)) return; /* below will do all node balanced alloc */ @@ -3558,14 +3577,7 @@ static void __init hugetlb_hstate_alloc_pages(struct hstate *h) /* list will be empty if hstate_is_gigantic */ prep_and_add_allocated_folios(h, &folio_list); - if (i < h->max_huge_pages) { - char buf[32]; - - string_get_size(huge_page_size(h), 1, STRING_UNITS_2, buf, 32); - pr_warn("HugeTLB: allocating %lu of page size %s failed. Only allocated %lu hugepages.\n", - h->max_huge_pages, buf, i); - h->max_huge_pages = i; - } + hugetlb_hstate_alloc_pages_errcheck(i, h); kfree(node_alloc_noretry); } -- cgit v1.2.3