Messages in this thread Patch in this message | | | Date | Wed, 08 Sep 2004 21:08:43 +0900 | From | Hiroyuki KAMEZAWA <> | Subject | [RFC][PATCH] no bitmap buddy allocator : removing atomic ops (4/4) |
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This part is part (4/4) and replaces atomic ops with non-atomic ops. This micro optimization can improve the performance of the no-bitmap buddy system.
To check effects of this patch. I made a tiny test.
************** test-program ******************** for(i = 0; i < 1000; i++) { mmap(16 Mega bytes, MAP_ANON); touch all pages; munmap(16 Mega bytes); } ************************************************ Results of this program. Host : Intex Xeon 1.8GHz x2, Memory 8Gbytes. Multi-user mode.
Reference Kernel --- linux-2.6.9-rc1-mm4 Total 0:35.79 System 33.89 User 1.88 Total 0:35.44 System 33.58 User 1.85 Total 0:35.75 System 33.81 User 1.91 Total 0:35.89 System 34.03 User 1.82 Total 0:35.93 System 34.03 User 1.84
No-bitmap without this micro-optimization patch Total 0:37.58 System 35.69 User 1.89 Total 0:37.52 System 35.66 User 1.86 Total 0:37.56 System 35.68 User 1.88 Total 0:37.64 System 35.76 User 1.88 Total 0:37.72 System 35.89 User 1.82
No-bitmap with this micro-optimization patch. Total 0:35.28 System 33.45 User 1.81 Total 0:35.38 System 33.62 User 1.75 Total 0:35.44 System 33.58 User 1.84 Total 0:35.52 System 33.58 User 1.90 Total 0:35.79 System 33.92 User 1.81
Single-user-mode.
reference-kernel linux-2.6.9-rc1-mm4: Total 0:35.20 System 33.32 User 1.88 Total 0:35.23 System 33.37 User 1.85 Total 0:35.58 System 33.77 User 1.81 Total 0:35.49 System 33.60 User 1.90 Total 0:35.79 System 33.80 User 1.99
No-bitmap without this micro-optimization patch Total 0:36.83 System 35.16 User 1.67 Total 0:36.45 System 34.66 User 1.79 Total 0:36.81 System 35.10 User 1.70 Total 0:36.89 System 35.24 User 1.65 Total 0:36.82 System 35.14 User 1.68
No-bitmap with this micor-optimization patch: Total 0:34.97 System 33.07 User 1.89 Total 0:34.94 System 32.98 User 1.95 Total 0:34.99 System 33.11 User 1.87 Total 0:34.90 System 33.14 User 1.76 Total 0:34.92 System 33.02 User 1.90
Results with this patch is better than ones without this by 2 seconds. 2/1000 = 2ms per 1 iteration (for 16 Megabytes alloc/free).
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
---
test-kernel-kamezawa/include/linux/page-flags.h | 2 ++ test-kernel-kamezawa/mm/page_alloc.c | 8 ++++---- 2 files changed, 6 insertions(+), 4 deletions(-)
diff -puN include/linux/page-flags.h~eliminate-bitmap-opt include/linux/page-flags.h --- test-kernel/include/linux/page-flags.h~eliminate-bitmap-opt 2004-09-08 18:48:43.115922392 +0900 +++ test-kernel-kamezawa/include/linux/page-flags.h 2004-09-08 18:48:43.120921632 +0900 @@ -239,6 +239,8 @@ extern unsigned long __read_page_state(u #define SetPagePrivate(page) set_bit(PG_private, &(page)->flags) #define ClearPagePrivate(page) clear_bit(PG_private, &(page)->flags) #define PagePrivate(page) test_bit(PG_private, &(page)->flags) +#define __SetPagePrivate(page) __set_bit(PG_private, &(page)->flags) +#define __ClearPagePrivate(page) __clear_bit(PG_private, &(page)->flags)
#define PageWriteback(page) test_bit(PG_writeback, &(page)->flags) #define SetPageWriteback(page) \ diff -puN mm/page_alloc.c~eliminate-bitmap-opt mm/page_alloc.c --- test-kernel/mm/page_alloc.c~eliminate-bitmap-opt 2004-09-08 18:48:43.118921936 +0900 +++ test-kernel-kamezawa/mm/page_alloc.c 2004-09-08 18:48:43.123921176 +0900 @@ -242,11 +242,11 @@ static inline void __free_pages_bulk (st page_idx &= buddy_idx; list_del(&buddy->lru); /* for propriety of PG_private bit, we clear it */ - ClearPagePrivate(buddy); + __ClearPagePrivate(buddy); } /* record the final order of the page */ coalesced_page = base + page_idx; - SetPagePrivate(coalesced_page); + __SetPagePrivate(coalesced_page); set_page_order(coalesced_page,order); list_add(&coalesced_page->lru, &zone->free_area[order].free_list); } @@ -347,7 +347,7 @@ expand(struct zone *zone, struct page *p list_add(&page[size].lru, &area->free_list); /* Note: already have lock, we don't need to use atomic ops */ set_page_order(&page[size], high); - SetPagePrivate(&page[size]); + __SetPagePrivate(&page[size]); } return page; } @@ -410,7 +410,7 @@ static struct page *__rmqueue(struct zon page = list_entry(area->free_list.next, struct page, lru); list_del(&page->lru); /* Note: already have lock, we don't need to use atomic ops */ - ClearPagePrivate(page); + __ClearPagePrivate(page); zone->free_pages -= 1UL << order; return expand(zone, page, order, current_order, area); } _
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