Hi Laura,
On Tuesday, June 05, 2012 9:27 PM Laura Abbott wrote:
Currently, when freeing 0 order pages, CMA pages are treated the same as regular movable pages, which means they end up on the per-cpu page list. This means that the CMA pages are likely to be allocated for something other than contigous memory. This increases the chance that the next alloc_contig_range will fail because pages can't be migrated.
Given the size of the CMA region is typically limited, it is best to optimize for success of alloc_contig_range as much as possible. Do this by freeing CMA pages directly instead of putting them on the per-cpu page lists.
Signed-off-by: Laura Abbott lauraa@codeaurora.org
mm/page_alloc.c | 3 ++- 1 files changed, 2 insertions(+), 1 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 0e1c6f5..c9a6483 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1310,7 +1310,8 @@ void free_hot_cold_page(struct page *page, int cold) * excessively into the page allocator */ if (migratetype >= MIGRATE_PCPTYPES) {
if (unlikely(migratetype == MIGRATE_ISOLATE)) {
if (unlikely(migratetype == MIGRATE_ISOLATE)|| is_migrate_cma(migratetype)) { free_one_page(zone, page, 0, migratetype); goto out;--
Well this patch has some side effects, in some cases it might force kernel to consume regular movable pages which should be left as a fallback for critical non-movable allocations. Do you have any statistics for the change introduced by this patch?
Best regards