mm: pass readahead info down to the i/o scheduler
Some i/o schedulers (i.e. row-iosched, cfq-iosched) deploy an idling
algorithm in order to be better synced with the readahead algorithm.
Idling is a prediction algorithm for incoming read requests.
In this patch we mark pages which are part of a readahead window, by
setting a newly introduced flag. With this flag, the i/o scheduler can
identify a request which is associated with a readahead page. This
enables the i/o scheduler's idling mechanism to be en-sync with the
readahead mechanism and, in turn, can increase read throughput.
Change-Id: I0654f23315b6d19d71bcc9cc029c6b281a44b196
Signed-off-by: Lee Susman <lsusman@codeaurora.org>
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 5148c1a..9cc2f45 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6093,6 +6093,7 @@
#ifdef CONFIG_MEMORY_FAILURE
{1UL << PG_hwpoison, "hwpoison" },
#endif
+ {1UL << PG_readahead, "PG_readahead" },
{-1UL, NULL },
};