diff options
| author | Nick Piggin <nickpiggin@yahoo.com.au> | 2006-01-06 00:11:21 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-01-06 08:33:29 -0800 |
| commit | b09eb1c06a14641209e6b86e9a5b28ea8287f193 (patch) | |
| tree | 1a3adbf25c05d7f6a585331260c2cdd7287e8c36 | |
| parent | a74609fafa2e5cc31d558012abaaa55ec9ad9da4 (diff) | |
[PATCH] mm: page_state opt docs
Comment the new locking rules for page_state statistics.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
| -rw-r--r-- | include/linux/page-flags.h | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index dede8d412dc..d52999c4333 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -79,13 +79,23 @@ /* * Global page accounting. One instance per CPU. Only unsigned longs are * allowed. + * + * - Fields can be modified with xxx_page_state and xxx_page_state_zone at + * any time safely (which protects the instance from modification by + * interrupt. + * - The __xxx_page_state variants can be used safely when interrupts are + * disabled. + * - The __xxx_page_state variants can be used if the field is only + * modified from process context, or only modified from interrupt context. + * In this case, the field should be commented here. */ struct page_state { unsigned long nr_dirty; /* Dirty writeable pages */ unsigned long nr_writeback; /* Pages under writeback */ unsigned long nr_unstable; /* NFS unstable pages */ unsigned long nr_page_table_pages;/* Pages used for pagetables */ - unsigned long nr_mapped; /* mapped into pagetables */ + unsigned long nr_mapped; /* mapped into pagetables. + * only modified from process context */ unsigned long nr_slab; /* In slab */ #define GET_PAGE_STATE_LAST nr_slab |