md/raid456: distribute raid processing over multiple cores

Now that the resources to handle stripe_head operations are allocated
percpu it is possible for raid5d to distribute stripe handling over
multiple cores.  This conversion also adds a call to cond_resched() in
the non-multicore case to prevent one core from getting monopolized for
raid operations.

Cc: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
index abb8636bfde..09c0c6e49ab 100644
--- a/drivers/md/Kconfig
+++ b/drivers/md/Kconfig
@@ -154,6 +154,17 @@ config MD_RAID456
 
           If unsure, say Y.
 
+config MULTICORE_RAID456
+        bool "RAID-4/RAID-5/RAID-6 Multicore processing (EXPERIMENTAL)"
+        depends on MD_RAID456
+        depends on SMP
+        depends on EXPERIMENTAL
+        ---help---
+          Enable the raid456 module to dispatch per-stripe raid operations to a
+          thread pool.
+
+          If unsure, say N.
+
 config MD_RAID6_PQ
         tristate