sparc64: Set VDS workqueue max_active argument to 0

Orabug: 23565322

Based on

https://www.kernel.org/doc/Documentation/workqueue.txt

The recommended value for max_active is 0:

max_active:

max_active determines the maximum number of execution contexts per
CPU which can be assigned to the work items of a wq.  For example,
with @max_active of 16, at most 16 work items of the wq can be
executing at the same time per CPU.

Currently, for a bound wq, the maximum limit for @max_active is 512
and the default value used when 0 is specified is 256.  For an unbound
wq, the limit is higher of 512 and 4 * num_possible_cpus().  These
values are chosen sufficiently high such that they are not the
limiting factor while providing protection in runaway cases.

The number of active work items of a wq is usually regulated by the
users of the wq, more specifically, by how many work items the users
may queue at the same time.  Unless there is a specific need for
throttling the number of active work items, specifying '0' is
recommended.

Signed-off-by: Bijan Mottahedeh <bijan.mottahedeh@oracle.com>
Reviewed-by: Liam Merwick <Liam.Merwick@oracle.com>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
(cherry picked from commit b584786e611e8e8a28830386e8b3db8874d794c5)
(cherry picked from commit f2559a96b70562267f01d5bb62ef44aa9f0c0cd8)
Signed-off-by: Allen Pais <allen.pais@oracle.com>

diff --git a/drivers/block/vds/vds_main.c b/drivers/block/vds/vds_main.c
index e67553a91475ab9c842ed5cfc3883738d6318538..9a467acd552906587ceefce22404a3fa52f99104 100644 (file)
--- a/drivers/block/vds/vds_main.c
+++ b/drivers/block/vds/vds_main.c
@@ -56,12 +56,10 @@ MODULE_VERSION(DRV_MOD_VERSION);
  * conceivably block when the backend is closed.  The serialization should
  * ensure that a following handshake initiates only after the reset is done.
  *
- * XXX The recommended value for the size of the kernel workqueue is 0 but
- * that creates threads which scale with ncpu and because of some apparent
- * flow control issues cause intermittent scsi timeouts and LDC aborts so
- * limit to 1 thread for now.
+ * The recommended value for the size of the kernel workqueue is 0;
+ * it creates threads which scale with ncpu.
  */
-int vds_wq = 1;
+int vds_wq;
 int vds_dbg;
 int vds_dbg_ldc;
 int vds_dbg_vio;