On Mon, 19 Aug 2013 14:23:40 +0200 Vlastimil Babka <vbabka@xxxxxxx> wrote:
> After introducing batching by pagevecs into munlock_vma_range(), we can further
> improve performance by bypassing the copying into per-cpu pagevec and the
> get_page/put_page pair associated with that. Instead we perform LRU putback
> directly from our pagevec. However, this is possible only for single-mapped
> pages that are evictable after munlock. Unevictable pages require rechecking
> after putting on the unevictable list, so for those we fallback to
> putback_lru_page(), hich handles that.
>
> After this patch, a 13% speedup was measured for munlocking a 56GB large memory
> area with THP disabled.
>
> ...
>
> +static void __putback_lru_fast(struct pagevec *pvec, int pgrescued)
> +{
> + count_vm_events(UNEVICTABLE_PGMUNLOCKED, pagevec_count(pvec));
> + /* This includes put_page so we don't call it explicitly */
This had me confused for a sec. __pagevec_lru_add() includes put_page,
so we don't call __pagevec_lru_add()? That's the problem with the word
"it" - one often doesn't know what it refers to.
Clarity:
--- a/mm/mlock.c~mm-munlock-bypass-per-cpu-pvec-for-putback_lru_page-fix
+++ a/mm/mlock.c
@@ -264,7 +264,10 @@ static bool __putback_lru_fast_prepare(s
static void __putback_lru_fast(struct pagevec *pvec, int pgrescued)
{
count_vm_events(UNEVICTABLE_PGMUNLOCKED, pagevec_count(pvec));
- /* This includes put_page so we don't call it explicitly */
+ /*
+ *__pagevec_lru_add() calls release_pages() so we don't call
+ * put_page() explicitly
+ */
__pagevec_lru_add(pvec);
count_vm_events(UNEVICTABLE_PGRESCUED, pgrescued);
}
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxx. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>