mm/memblock: introduce a new helper memblock_estimated_nr_free_pages()
Subsystems (5)
PATCH v4 1/3 mm/memblock: introduce a new helper memblock_estimated_nr_free_pages()
During bootup, system may need the number of free pages in the whole system to do some calculation before all pages are freed to buddy system. Usually this number is get from totalram_pages(). Since we plan to move the free pages accounting in __free_pages_core(), this value may not represent total free pages at the early stage, especially when CONFIG_DEFERRED_STRUCT_PAGE_INIT is enabled.
Instead of using raw memblock api, let's introduce a new helper for user to get the estimated number of free pages from memblock point of view.
---
v4: adjust comment per david's suggestion
--- include/linux/memblock.h | 1 + mm/memblock.c | 20 ++++++++++++++++++++ 2 files changed, 21 insertions(+)
include/linux/memblock.h +1 -0
@@ -486,6 +486,7 @@ static inline __init_memblock bool memblock_bottom_up(void)phys_addr_t memblock_phys_mem_size (void );phys_addr_t memblock_reserved_size (void ); +unsigned long memblock_estimated_nr_pages (void );phys_addr_t memblock_start_of_DRAM (void );phys_addr_t memblock_end_of_DRAM (void );void memblock_enforce_memory_limit (phys_addr_t memory_limit);
mm/memblock.c +20 -0
@@ -1729,6 +1729,26 @@ phys_addr_t __init_memblock memblock_reserved_size(void)return memblock.reserved.total_size; } +/** +* memblock_estimated_nr_free_pages - return estimated number of free pages +* from memblock point of view +* +* During bootup, subsystems might need a rough estimate of the number of free +* pages in the whole system, before precise numbers are available from the +* buddy. Especially with CONFIG_DEFERRED_STRUCT_PAGE_INIT, the numbers +* obtained from the buddy might be very imprecise during bootup. +* +* While we can get the estimated number of free pages from memblock, which is +* good enough for estimation. +* +* Return: +* An estimated number of free pages from memblock point of view. +*/ +unsigned long __init memblock_estimated_nr_free_pages (void ) +{ +return PHYS_PFN (memblock_phys_mem_size () -memblock_reserved_size ()); +} +/* lowest address */ phys_addr_t __init_memblock memblock_start_of_DRAM(void) {
Signature · 1 line
2.34.1
PATCH v4 2/3 kernel/fork.c: get totalram_pages from memblock to calculate max_threads
Since we plan to move the accounting into __free_pages_core(), totalram_pages may not represent the total usable pages on system at this point when defer_init is enabled.
Instead we can get the total estimated pages from memblock directly.
--- kernel/fork.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
kernel/fork.c +2 -1
@@ -44,6 +44,7 @@#include <linux/fs.h> #include <linux/mm.h> #include <linux/mm_inline.h> +#include <linux/memblock.h> #include <linux/nsproxy.h> #include <linux/capability.h> #include <linux/cpu.h>
@@ -999,7 +1000,7 @@ void __init __weak arch_task_cache_init(void) { }static void set_max_threads (unsigned int max_threads_suggested) {u64 threads; -unsigned long nr_pages =totalram_pages (); +unsigned long nr_pages =memblock_estimated_nr_pages ();/* * The number of threads shall be limited such that the thread
Signature · 1 line
2.34.1
Re: [PATCH v4 2/3] kernel/fork.c: get totalram_pages from memblock to calculate max_threads
Quoted 27 lines · Wei Yang
Since we plan to move the accounting into
__free_pages_core(),totalram_pagesmay not represent the total usable pages on system at this point whendefer_initis enabled.Instead we can get the total estimated pages from memblock directly.
Signed-off-by Wei Yang <[email protected]>CC Mike Rapoport (IBM) <[email protected]>CC David Hildenbrand <[email protected]>CC Oleg Nesterov <[email protected]>--- kernel/fork.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)kernel/fork.c +1
-0@@ -44,6 +44,7 @@#include <linux/fs.h> #include <linux/mm.h> #include <linux/mm_inline.h> +#include <linux/memblock.h> #include <linux/nsproxy.h> #include <linux/capability.h> #include <linux/cpu.h>
kernel/fork.c void __init __weak arch_task_cache_init(void) { } · line 1003
Quoted 5 lines
kernel/fork.c +1
-1@@ -999,7 +1000,7 @@ void __init __weak arch_task_cache_init(void) { }static void set_max_threads (unsigned int max_threads_suggested) {u64 threads; -unsigned long nr_pages =totalram_pages (); +unsigned long nr_pages =memblock_estimated_nr_pages ();
Stale name
Signature · 3 lines
Cheers, David / dhildenb
PATCH v4 3/3 kernel/fork.c: put set_max_threads()/task_struct_whitelist() in __init section
In reply to Wei YangFunction set_max_threads()/task_struct_whitelist() is only used by fork_init() during bootup.
Let's add __init tag to them.
--- kernel/fork.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
kernel/fork.c +2 -2
@@ -997,7 +997,7 @@ void __init __weak arch_task_cache_init(void) { }/* * set_max_threads */ -static void set_max_threads (unsigned int max_threads_suggested) +static void __init set_max_threads (unsigned int max_threads_suggested) {u64 threads;unsigned long nr_pages =memblock_estimated_nr_pages ();
@@ -1023,7 +1023,7 @@ static void set_max_threads(unsigned int max_threads_suggested)int arch_task_struct_size__read_mostly ;#endif -static void task_struct_whitelist (unsigned long *offset,unsigned long *size) +static void __init task_struct_whitelist (unsigned long *offset,unsigned long *size) {/* Fetch thread_struct whitelist for the architecture. */ arch_thread_struct_whitelist (offset, size);
Signature · 1 line
2.34.1
Quoted 26 lines · Wei Yang
During bootup, system may need the number of free pages in the whole system to do some calculation before all pages are freed to buddy system. Usually this number is get from
totalram_pages(). Since we plan to move the free pages accounting in__free_pages_core(), this value may not represent total free pages at the early stage, especially whenCONFIG_DEFERRED_STRUCT_PAGE_INITis enabled.Instead of using raw memblock api, let's introduce a new helper for user to get the estimated number of free pages from memblock point of view.
Signed-off-by Wei Yang <[email protected]>CC David Hildenbrand <[email protected]>Reviewed-by David Hildenbrand <[email protected]>---
v4: adjust comment per david's suggestion--- include/linux/memblock.h | 1 + mm/memblock.c | 20 ++++++++++++++++++++ 2 files changed, 21 insertions(+)include/linux/memblock.h +0
-0
include/linux/memblock.h static inline __init_memblock bool memblock_bottom_up(void) · line 489
Quoted 4 lines
include/linux/memblock.h +1
-0@@ -486,6 +486,7 @@ static inline __init_memblock bool memblock_bottom_up(void)phys_addr_t memblock_phys_mem_size (void );phys_addr_t memblock_reserved_size (void ); +unsigned long memblock_estimated_nr_pages (void );
^ stale name
Quoted 12 lines
include/linux/memblock.h +0
-0phys_addr_t memblock_start_of_DRAM (void );phys_addr_t memblock_end_of_DRAM (void );void memblock_enforce_memory_limit (phys_addr_t memory_limit);mm/memblock.c +1
-0@@ -1729,6 +1729,26 @@ phys_addr_t __init_memblock memblock_reserved_size(void)return memblock.reserved.total_size; } +/**
mm/memblock.c phys_addr_t __init_memblock memblock_reserved_size(void) · line 1742
Quoted 10 lines
mm/memblock.c +10
-0+* memblock_estimated_nr_free_pages - return estimated number of free pages +* from memblock point of view +* +* During bootup, subsystems might need a rough estimate of the number of free +* pages in the whole system, before precise numbers are available from the +* buddy. Especially with CONFIG_DEFERRED_STRUCT_PAGE_INIT, the numbers +* obtained from the buddy might be very imprecise during bootup. +* +* While we can get the estimated number of free pages from memblock, which is +* good enough for estimation.
I'd drop that sentence.
Apart form that LGTM
Signature · 3 lines
Cheers, David / dhildenb
Quoted 22 lines · David Hildenbrand
Quoted 21 lines · Wei Yang
During bootup, system may need the number of free pages in the whole system to do some calculation before all pages are freed to buddy system. Usually this number is get from
totalram_pages(). Since we plan to move the free pages accounting in__free_pages_core(), this value may not represent total free pages at the early stage, especially whenCONFIG_DEFERRED_STRUCT_PAGE_INITis enabled.Instead of using raw memblock api, let's introduce a new helper for user to get the estimated number of free pages from memblock point of view.
Signed-off-by Wei Yang <[email protected]>CC David Hildenbrand <[email protected]>Reviewed-by David Hildenbrand <[email protected]>---
v4: adjust comment per david's suggestion--- include/linux/memblock.h | 1 + mm/memblock.c | 20 ++++++++++++++++++++ 2 files changed, 21 insertions(+)
Quoted 10 lines
include/linux/memblock.h static inline __init_memblock bool memblock_bottom_up(void) · line 488
Quoted 8 lines
include/linux/memblock.h +1
-0@@ -486,6 +486,7 @@ static inline __init_memblock bool memblock_bottom_up(void)phys_addr_t memblock_phys_mem_size (void );phys_addr_t memblock_reserved_size (void ); +unsigned long memblock_estimated_nr_pages (void );^ stale name
My bad.
Quoted 16 lines
Quoted 16 lines
include/linux/memblock.h +0
-0phys_addr_t memblock_start_of_DRAM (void );phys_addr_t memblock_end_of_DRAM (void );void memblock_enforce_memory_limit (phys_addr_t memory_limit);mm/memblock.c +5
-0@@ -1729,6 +1729,26 @@ phys_addr_t __init_memblock memblock_reserved_size(void)return memblock.reserved.total_size; } +/** +* memblock_estimated_nr_free_pages - return estimated number of free pages +* from memblock point of view +* +* During bootup, subsystems might need a rough estimate of the number of free
Quoted 9 lines
mm/memblock.c phys_addr_t __init_memblock memblock_reserved_size(void) · line 1742
Quoted 6 lines
mm/memblock.c +6
-0+* pages in the whole system, before precise numbers are available from the +* buddy. Especially with CONFIG_DEFERRED_STRUCT_PAGE_INIT, the numbers +* obtained from the buddy might be very imprecise during bootup. +* +* While we can get the estimated number of free pages from memblock, which is +* good enough for estimation. I'd drop that sentence.
Will update it.
Quoted 7 lines
Apart form that LGTM
Signature · 3 lines
Cheers, David / dhildenb
Signature · 2 lines
Wei Yang Help you, Help me