Hi,
Followings are patches for removing bitmaps from buddy allocator, against 2.6.9-rc3.
I think this version is much clearer than ones I posted a month ago.
The problem I was worried about was how to deal with memmap's holes in a zone.
and I decided to use pfn_valid() simply. Now, there is no messy codes :)
pfn_valid() is used when macro "HOLES_IN_ZONE" is defined.
It is defined only in ia64 now.
Here is kernbench result on my tiger4 (Itanium2 1.3GHz x2, 8 Gbytes memory)
Average Optimal -j 8 Load Run (Perfroming 5 run of make -j 8 on linux-2.6.8 source tree):
Elapsed Time User Time System Time Percent CPU Context Switches Sleeps
2.6.9-rc3 699.906 1322.01 39.336 194 64390 74416.8
no-bitmap 698.334 1321.79 38.58 194.2 64435.4 74622.2
If there is unclear point, please tell me.
Thanks.
Kame <[email protected]>
=== patch for include files ===
This patch removes bitmap from zone->free_area[] in include/linux/mmzone.h,
and adds some comments on page->private field in include/linux/mm.h.
non-atomic ops for changing PG_private bit is added in include/page-flags.h.
zone->lock is always acquired when PG_private of "a free page" is changed.
Signed-off-by: KAMEZAWA Hiroyuki <[email protected]>
---
test-kernel-kamezawa/include/linux/mm.h | 2 ++
test-kernel-kamezawa/include/linux/mmzone.h | 1 -
test-kernel-kamezawa/include/linux/page-flags.h | 2 ++
3 files changed, 4 insertions(+), 1 deletion(-)
diff -puN include/linux/mm.h~eliminate-bitmap-includes include/linux/mm.h
--- test-kernel/include/linux/mm.h~eliminate-bitmap-includes 2004-10-07 17:18:34.062982800 +0900
+++ test-kernel-kamezawa/include/linux/mm.h 2004-10-07 17:18:34.070981584 +0900
@@ -209,6 +209,8 @@ struct page {
* usually used for buffer_heads
* if PagePrivate set; used for
* swp_entry_t if PageSwapCache
+ * When page is free, this indicates
+ * order in the buddy system.
*/
struct address_space *mapping; /* If low bit clear, points to
* inode address_space, or NULL.
diff -puN include/linux/mmzone.h~eliminate-bitmap-includes include/linux/mmzone.h
--- test-kernel/include/linux/mmzone.h~eliminate-bitmap-includes 2004-10-07 17:18:34.065982344 +0900
+++ test-kernel-kamezawa/include/linux/mmzone.h 2004-10-07 17:18:34.071981432 +0900
@@ -22,7 +22,6 @@
struct free_area {
struct list_head free_list;
- unsigned long *map;
};
struct pglist_data;
diff -puN include/linux/page-flags.h~eliminate-bitmap-includes include/linux/page-flags.h
--- test-kernel/include/linux/page-flags.h~eliminate-bitmap-includes 2004-10-07 17:18:34.067982040 +0900
+++ test-kernel-kamezawa/include/linux/page-flags.h 2004-10-07 17:18:34.071981432 +0900
@@ -238,6 +238,8 @@ 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) \
_
> Followings are patches for removing bitmaps from buddy allocator, against 2.6.9-rc3.
> I think this version is much clearer than ones I posted a month ago.
...
> If there is unclear point, please tell me.
What was the purpose behind this, again? Sorry, has been too long since
I last looked.
M.
--On Thursday, October 07, 2004 07:45:21 -0700 "Martin J. Bligh"
<[email protected]> wrote:
>> Followings are patches for removing bitmaps from buddy allocator,
>> against 2.6.9-rc3. I think this version is much clearer than ones I
>> posted a month ago.
> ...
>> If there is unclear point, please tell me.
>
> What was the purpose behind this, again? Sorry, has been too long since
> I last looked.
The memory allocator bitmaps are the main remaining reason we need the
concept of linear memory. If we can get rid of them, it's one step closer
to managing memory as a set of sections.
Dave McCracken