From 188f87f2648b13f5de17d5e068f18d317e0c1f98 Mon Sep 17 00:00:00 2001 From: Eric Chanudet Date: Wed, 22 May 2024 16:38:01 -0400 Subject: [PATCH] mm/mm_init: use node's number of cpus in deferred_page_init_max_threads x86_64 is already using the node's cpu as maximum threads. Make that the default for all archs setting DEFERRED_STRUCT_PAGE_INIT. This returns to the behavior prior making the function arch-specific with commit ecd096506922 ("mm: make deferred init's max threads arch-specific"). Setting DEFERRED_STRUCT_PAGE_INIT and testing on a few arm64 platforms shows faster deferred_init_memmap completions: | | x13s | SA8775p-ride | Ampere R137-P31 | Ampere HR330 | | | Metal, 32GB | VM, 36GB | VM, 58GB | Metal, 128GB | | | 8cpus | 8cpus | 8cpus | 32cpus | |---------|-------------|--------------|-----------------|--------------| | threads | ms (%) | ms (%) | ms (%) | ms (%) | |---------|-------------|--------------|-----------------|--------------| | 1 | 108 (0%) | 72 (0%) | 224 (0%) | 324 (0%) | | cpus | 24 (-77%) | 36 (-50%) | 40 (-82%) | 56 (-82%) | Michael Ellerman reported: : On a machine here (1TB, 40 cores, 4KB pages) the existing code gives: : : [ 0.500124] node 2 deferred pages initialised in 210ms : [ 0.515790] node 3 deferred pages initialised in 230ms : [ 0.516061] node 0 deferred pages initialised in 230ms : [ 0.516522] node 7 deferred pages initialised in 230ms : [ 0.516672] node 4 deferred pages initialised in 230ms : [ 0.516798] node 6 deferred pages initialised in 230ms : [ 0.517051] node 5 deferred pages initialised in 230ms : [ 0.523887] node 1 deferred pages initialised in 240ms : : vs with the patch: : : [ 0.379613] node 0 deferred pages initialised in 90ms : [ 0.380388] node 1 deferred pages initialised in 90ms : [ 0.380540] node 4 deferred pages initialised in 100ms : [ 0.390239] node 6 deferred pages initialised in 100ms : [ 0.390249] node 2 deferred pages initialised in 100ms : [ 0.390786] node 3 deferred pages initialised in 110ms : [ 0.396721] node 5 deferred pages initialised in 110ms : [ 0.397095] node 7 deferred pages initialised in 110ms : : Which is a nice speedup. [echanude@redhat.com: v3] Link: https://lkml.kernel.org/r/20240528185455.643227-4-echanude@redhat.com Link: https://lkml.kernel.org/r/20240522203758.626932-4-echanude@redhat.com Signed-off-by: Eric Chanudet Tested-by: Michael Ellerman (powerpc) Reviewed-by: Baoquan He Acked-by: Alexander Gordeev Acked-by: Mike Rapoport (IBM) Cc: Andy Lutomirski Cc: Borislav Petkov (AMD) Cc: Dave Hansen Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Nicholas Piggin Cc: Peter Zijlstra Cc: Thomas Gleixner Signed-off-by: Andrew Morton --- arch/x86/mm/init_64.c | 12 ------------ include/linux/memblock.h | 2 -- mm/mm_init.c | 5 ++--- 3 files changed, 2 insertions(+), 17 deletions(-) diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c index 7e177856ee4f..adec42928ec1 100644 --- a/arch/x86/mm/init_64.c +++ b/arch/x86/mm/init_64.c @@ -1354,18 +1354,6 @@ void __init mem_init(void) preallocate_vmalloc_pages(); } -#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT -int __init deferred_page_init_max_threads(const struct cpumask *node_cpumask) -{ - /* - * More CPUs always led to greater speedups on tested systems, up to - * all the nodes' CPUs. Use all since the system is otherwise idle - * now. - */ - return max_t(int, cpumask_weight(node_cpumask), 1); -} -#endif - int kernel_set_to_readonly; void mark_rodata_ro(void) diff --git a/include/linux/memblock.h b/include/linux/memblock.h index e2082240586d..40c62aca36ec 100644 --- a/include/linux/memblock.h +++ b/include/linux/memblock.h @@ -335,8 +335,6 @@ void __next_mem_pfn_range_in_zone(u64 *idx, struct zone *zone, for (; i != U64_MAX; \ __next_mem_pfn_range_in_zone(&i, zone, p_start, p_end)) -int __init deferred_page_init_max_threads(const struct cpumask *node_cpumask); - #endif /* CONFIG_DEFERRED_STRUCT_PAGE_INIT */ /** diff --git a/mm/mm_init.c b/mm/mm_init.c index 3ec04933f7fd..779b4e3d6339 100644 --- a/mm/mm_init.c +++ b/mm/mm_init.c @@ -2122,11 +2122,10 @@ deferred_init_memmap_chunk(unsigned long start_pfn, unsigned long end_pfn, } } -/* An arch may override for more concurrency. */ -__weak int __init +static unsigned int __init deferred_page_init_max_threads(const struct cpumask *node_cpumask) { - return 1; + return max(cpumask_weight(node_cpumask), 1U); } /* Initialise remaining memory on a node */