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Subject[PATCH 11/14] mm: meminit: Control parallel memory initialisation from command line and config
Date
Patch adds a defer_meminit=[enable|disable] kernel command line
option. Default is controlled by Kconfig.

Signed-off-by: Mel Gorman <mgorman@suse.de>
---
Documentation/kernel-parameters.txt | 8 ++++++++
include/linux/mmzone.h | 14 ++++++++++++++
init/main.c | 1 +
mm/Kconfig | 10 ++++++++++
mm/page_alloc.c | 24 ++++++++++++++++++++++++
5 files changed, 57 insertions(+)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index bfcb1a62a7b4..867338fc5941 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -807,6 +807,14 @@ bytes respectively. Such letter suffixes can also be entirely omitted.

debug_objects [KNL] Enable object debugging

+ defer_meminit= [KNL,X86] Enable or disable deferred memory init.
+ Large machine may take a long time to initialise
+ memory management structures. If this is enabled
+ then memory initialisation is deferred to kswapd
+ and each memory node is initialised in parallel.
+ In very early boot, there will be less memory that
+ will rapidly increase while it is initialised.
+
no_debug_objects
[KNL] Disable object debugging

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 20c2da89a14d..1275f9a8cb42 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -823,6 +823,20 @@ static inline struct zone *lruvec_zone(struct lruvec *lruvec)
#endif
}

+
+#ifdef CONFIG_DEFERRED_MEM_INIT
+extern bool deferred_mem_init_enabled;
+static inline void setup_deferred_meminit(void)
+{
+ if (IS_ENABLED(CONFIG_DEFERRED_MEM_INIT_DEFAULT_ENABLED))
+ deferred_mem_init_enabled = true;
+}
+#else
+static inline void setup_deferred_meminit(void)
+{
+}
+#endif /* CONFIG_DEFERRED_MEM_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 463c7005c3d9..0eb9b1349cc2 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -648,3 +648,13 @@ config DEFERRED_MEM_INIT
of the system it will still be busy initialising struct pages. This
has a potential performance impact on processes until kswapd finishes
the initialisation.
+
+config DEFERRED_MEM_INIT_DEFAULT_ENABLED
+ bool "Automatically enable deferred memory initialisation"
+ default y
+ depends on DEFERRED_MEM_INIT
+ help
+ If set, memory initialisation will be deferred by default on large
+ memory configurations. If DEFERRED_MEM_INIT is set then it is a
+ reasonable default to enable this too. User will need to disable
+ this if allocate huge pages from the command line.
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 21bb818aa3c4..cb38583063cb 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_MEM_INIT
+bool __meminitdata deferred_mem_init_enabled;
+
static inline void reset_deferred_meminit(pg_data_t *pgdat)
{
pgdat->first_deferred_pfn = ULONG_MAX;
@@ -268,6 +270,9 @@ static inline bool update_defer_init(pg_data_t *pgdat,
unsigned long pfn,
unsigned long *nr_initialised)
{
+ if (!deferred_mem_init_enabled)
+ return true;
+
if (pgdat->first_deferred_pfn != ULONG_MAX)
return false;

@@ -281,6 +286,25 @@ 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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