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Message-ID: <20240520231555.395979-5-echanude@redhat.com>
Date: Mon, 20 May 2024 19:15:59 -0400
From: Eric Chanudet <echanude@...hat.com>
To: Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will@...nel.org>,
Baoquan He <bhe@...hat.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Zhen Lei <thunder.leizhen@...wei.com>,
Yajun Deng <yajun.deng@...ux.dev>,
"Mike Rapoport (IBM)" <rppt@...nel.org>,
Zhang Jianhua <chris.zjh@...wei.com>,
linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org
Cc: Eric Chanudet <echanude@...hat.com>
Subject: [PATCH] arm64: init: override deferred_page_init_max_threads
This was the behavior prior to making the function arch-specific with
commit ecd096506922 ("mm: make deferred init's max threads
arch-specific")
Architectures can override the generic implementation that uses only one
CPU. 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%) |
Signed-off-by: Eric Chanudet <echanude@...hat.com>
---
arch/arm64/mm/init.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 9b5ab6818f7f..71f5188fe63d 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -158,6 +158,13 @@ static void __init zone_sizes_init(void)
free_area_init(max_zone_pfns);
}
+#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
+int __init deferred_page_init_max_threads(const struct cpumask *node_cpumask)
+{
+ return max_t(int, cpumask_weight(node_cpumask), 1);
+}
+#endif
+
int pfn_is_map_memory(unsigned long pfn)
{
phys_addr_t addr = PFN_PHYS(pfn);
--
2.44.0
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