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Subject[PATCH 10/13] x86: mm: Enable deferred struct page initialisation on x86-64
Date
This patch adds the Kconfig logic to add deferred struct page initialisation
to x86-64 if NUMA is enabled. Other architectures may enable on a
case-by-case basis after auditing early_pfn_to_nid and testing.

Signed-off-by: Mel Gorman <mgorman@suse.de>
---
Documentation/kernel-parameters.txt | 6 ++++++
arch/x86/Kconfig | 1 +
include/linux/mmzone.h | 14 ++++++++++++++
init/main.c | 1 +
mm/Kconfig | 28 ++++++++++++++++++++++++++++
mm/page_alloc.c | 21 +++++++++++++++++++++
6 files changed, 71 insertions(+)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index bfcb1a62a7b4..e7c6f7486214 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -807,6 +807,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted.

debug_objects [KNL] Enable object debugging

+ defer_meminit= [KNL,X86] Enable or disable deferred struct page init.
+ Large machine may take a long time to initialise
+ memory management structures. If enabled then a
+ subset of struct pages are initialised and kswapd
+ initialses the rest in parallel.
+
no_debug_objects
[KNL] Disable object debugging

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index b7d31ca55187..d15d74a052d5 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -32,6 +32,7 @@ config X86
select HAVE_UNSTABLE_SCHED_CLOCK
select ARCH_SUPPORTS_NUMA_BALANCING if X86_64
select ARCH_SUPPORTS_INT128 if X86_64
+ select ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT if X86_64 && NUMA
select HAVE_IDE
select HAVE_OPROFILE
select HAVE_PCSPKR_PLATFORM
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 821f5000dec9..8ac074db364f 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -822,6 +822,20 @@ static inline struct zone *lruvec_zone(struct lruvec *lruvec)
#endif
}

+
+#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
+extern bool deferred_mem_init_enabled;
+static inline void setup_deferred_meminit(void)
+{
+ if (IS_ENABLED(CONFIG_DEFERRED_STRUCT_PAGE_INIT_DEFAULT_ENABLED))
+ deferred_mem_init_enabled = true;
+}
+#else
+static inline void setup_deferred_meminit(void)
+{
+}
+#endif /* CONFIG_DEFERRED_STRUCT_PAGE_INIT */
+
#ifdef CONFIG_HAVE_MEMORY_PRESENT
void memory_present(int nid, unsigned long start, unsigned long end);
#else
diff --git a/init/main.c b/init/main.c
index 6f0f1c5ff8cc..f339d37a43e8 100644
--- a/init/main.c
+++ b/init/main.c
@@ -506,6 +506,7 @@ asmlinkage __visible void __init start_kernel(void)
boot_init_stack_canary();

cgroup_init_early();
+ setup_deferred_meminit();

local_irq_disable();
early_boot_irqs_disabled = true;
diff --git a/mm/Kconfig b/mm/Kconfig
index a03131b6ba8e..87a4535e0df4 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -629,3 +629,31 @@ config MAX_STACK_SIZE_MB
changed to a smaller value in which case that is used.

A sane initial value is 80 MB.
+
+# For architectures that support deferred memory initialisation
+config ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
+ bool
+
+config DEFERRED_STRUCT_PAGE_INIT
+ bool "Defer initialisation of struct pages to kswapd"
+ default n
+ depends on ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
+ depends on MEMORY_HOTPLUG
+ help
+ Ordinarily all struct pages are initialised during early boot in a
+ single thread. On very large machines this can take a considerable
+ amount of time. If this option is set, large machines will bring up
+ a subset of memmap at boot and then initialise the rest in parallel
+ when kswapd starts. This has a potential performance impact on
+ processes running early in the lifetime of the systemm until kswapd
+ finishes the initialisation.
+
+config DEFERRED_STRUCT_PAGE_INIT_DEFAULT_ENABLED
+ bool "Automatically enable deferred struct page initialisation"
+ default y
+ depends on DEFERRED_STRUCT_PAGE_INIT
+ help
+ If set, struct page initialisation will be deferred by default on
+ large memory configurations. If DEFERRED_STRUCT_PAGE_INIT is set
+ then it is a reasonable default to enable this too. User may need
+ to disable this if allocating huge pages from the command line.
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 839e4c73ce6d..6b2f6c21b70f 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -236,6 +236,8 @@ EXPORT_SYMBOL(nr_online_nodes);
int page_group_by_mobility_disabled __read_mostly;

#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
+bool __meminitdata deferred_mem_init_enabled;
+
static inline void reset_deferred_meminit(pg_data_t *pgdat)
{
pgdat->first_deferred_pfn = ULONG_MAX;
@@ -285,6 +287,25 @@ static inline bool update_defer_init(pg_data_t *pgdat,

return true;
}
+
+static int __init setup_deferred_mem_init(char *str)
+{
+ if (!str)
+ return -1;
+
+ if (!strcmp(str, "enable")) {
+ deferred_mem_init_enabled = true;
+ } else if (!strcmp(str, "disable")) {
+ deferred_mem_init_enabled = false;
+ } else {
+ pr_warn("Unable to parse deferred_mem_init=\n");
+ return -1;
+ }
+
+ return 0;
+}
+
+early_param("defer_meminit", setup_deferred_mem_init);
#else
static inline void reset_deferred_meminit(pg_data_t *pgdat)
{
--
2.1.2


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