The quilt patch titled
Subject: mm/mm_init: use node's number of cpus in deferred_page_init_max_threads
has been removed from the -mm tree. Its filename was
mm-mm_init-use-nodes-number-of-cpus-in-deferred_page_init_max_threads.patch
This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Eric Chanudet <echanude@xxxxxxxxxx>
Subject: mm/mm_init: use node's number of cpus in deferred_page_init_max_threads
Date: Wed, 22 May 2024 16:38:01 -0400
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@xxxxxxxxxx: v3]
Link: https://lkml.kernel.org/r/20240528185455.643227-4-echanude@xxxxxxxxxx
Link: https://lkml.kernel.org/r/20240522203758.626932-4-echanude@xxxxxxxxxx
Signed-off-by: Eric Chanudet <echanude@xxxxxxxxxx>
Tested-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx> (powerpc)
Reviewed-by: Baoquan He <bhe@xxxxxxxxxx>
Acked-by: Alexander Gordeev <agordeev@xxxxxxxxxxxxx>
Acked-by: Mike Rapoport (IBM) <rppt@xxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Nicholas Piggin <npiggin@xxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/x86/mm/init_64.c | 12 ------------
include/linux/memblock.h | 2 --
mm/mm_init.c | 5 ++---
3 files changed, 2 insertions(+), 17 deletions(-)
--- a/arch/x86/mm/init_64.c~mm-mm_init-use-nodes-number-of-cpus-in-deferred_page_init_max_threads
+++ a/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)
--- a/include/linux/memblock.h~mm-mm_init-use-nodes-number-of-cpus-in-deferred_page_init_max_threads
+++ a/include/linux/memblock.h
@@ -335,8 +335,6 @@ void __next_mem_pfn_range_in_zone(u64 *i
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 */
/**
--- a/mm/mm_init.c~mm-mm_init-use-nodes-number-of-cpus-in-deferred_page_init_max_threads
+++ a/mm/mm_init.c
@@ -2122,11 +2122,10 @@ deferred_init_memmap_chunk(unsigned long
}
}
-/* 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 */
_
Patches currently in -mm which might be from echanude@xxxxxxxxxx are
