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author | 2014-01-21 15:49:07 -0800 | |
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committer | 2014-01-21 16:19:44 -0800 | |
commit | b35f1819acd9243a3ff7ad25b1fa8bd6bfe80fb2 (patch) | |
tree | 140f810d09226caa12531e0a02126af64e71e314 /include/linux/mm.h | |
parent | mm: get rid of unnecessary pageblock scanning in setup_zone_migrate_reserve (diff) | |
download | linux-b35f1819acd9243a3ff7ad25b1fa8bd6bfe80fb2.tar.gz linux-b35f1819acd9243a3ff7ad25b1fa8bd6bfe80fb2.tar.bz2 linux-b35f1819acd9243a3ff7ad25b1fa8bd6bfe80fb2.zip |
mm: create a separate slab for page->ptl allocation
If DEBUG_SPINLOCK and DEBUG_LOCK_ALLOC are enabled spinlock_t on x86_64
is 72 bytes. For page->ptl they will be allocated from kmalloc-96 slab,
so we loose 24 on each. An average system can easily allocate few tens
thousands of page->ptl and overhead is significant.
Let's create a separate slab for page->ptl allocation to solve this.
To make sure that it really works this time, some numbers from my test
machine (just booted, no load):
Before:
# grep '^\(kmalloc-96\|page->ptl\)' /proc/slabinfo
kmalloc-96 31987 32190 128 30 1 : tunables 120 60 8 : slabdata 1073 1073 92
After:
# grep '^\(kmalloc-96\|page->ptl\)' /proc/slabinfo
page->ptl 27516 28143 72 53 1 : tunables 120 60 8 : slabdata 531 531 9
kmalloc-96 3853 5280 128 30 1 : tunables 120 60 8 : slabdata 176 176 0
Note that the patch is useful not only for debug case, but also for
PREEMPT_RT, where spinlock_t is always bloated.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/mm.h')
-rw-r--r-- | include/linux/mm.h | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h index 58202c26c559..fc4415256ec3 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1350,6 +1350,7 @@ static inline pmd_t *pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long a #if USE_SPLIT_PTE_PTLOCKS #if ALLOC_SPLIT_PTLOCKS +void __init ptlock_cache_init(void); extern bool ptlock_alloc(struct page *page); extern void ptlock_free(struct page *page); @@ -1358,6 +1359,10 @@ static inline spinlock_t *ptlock_ptr(struct page *page) return page->ptl; } #else /* ALLOC_SPLIT_PTLOCKS */ +static inline void ptlock_cache_init(void) +{ +} + static inline bool ptlock_alloc(struct page *page) { return true; @@ -1410,10 +1415,17 @@ static inline spinlock_t *pte_lockptr(struct mm_struct *mm, pmd_t *pmd) { return &mm->page_table_lock; } +static inline void ptlock_cache_init(void) {} static inline bool ptlock_init(struct page *page) { return true; } static inline void pte_lock_deinit(struct page *page) {} #endif /* USE_SPLIT_PTE_PTLOCKS */ +static inline void pgtable_init(void) +{ + ptlock_cache_init(); + pgtable_cache_init(); +} + static inline bool pgtable_page_ctor(struct page *page) { inc_zone_page_state(page, NR_PAGETABLE); |