Patchwork [Open-FCoE,03/13] libfc: Micro-optimize fc_setup_exch_mgr()

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Submitter Bart Van Assche
Date Aug. 14, 2013, 7:33 a.m.
Message ID <520B32CF.7080904@acm.org>
Download mbox | patch
Permalink /patch/87/
State Accepted
Headers show

Comments

Bart Van Assche - Aug. 14, 2013, 7:33 a.m.
Convert a loop into an ilog2() call. Although this code is not performance
sensitive this conversion makes this code easier to read.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Cc: Robert Love <robert.w.love@intel.com>
Cc: Neil Horman <nhorman@tuxdriver.com>
---
 drivers/scsi/libfc/fc_exch.c |   10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

Patch

diff --git a/drivers/scsi/libfc/fc_exch.c b/drivers/scsi/libfc/fc_exch.c
index cb2b900..d0be52a 100644
--- a/drivers/scsi/libfc/fc_exch.c
+++ b/drivers/scsi/libfc/fc_exch.c
@@ -27,6 +27,7 @@ 
 #include <linux/slab.h>
 #include <linux/err.h>
 #include <linux/export.h>
+#include <linux/log2.h>
 
 #include <scsi/fc/fc_fc2.h>
 
@@ -2530,13 +2531,8 @@  int fc_setup_exch_mgr(void)
 	 * cpu on which exchange originated by simple bitwise
 	 * AND operation between fc_cpu_mask and exchange id.
 	 */
-	fc_cpu_mask = 1;
-	fc_cpu_order = 0;
-	while (fc_cpu_mask < nr_cpu_ids) {
-		fc_cpu_mask <<= 1;
-		fc_cpu_order++;
-	}
-	fc_cpu_mask--;
+	fc_cpu_order = ilog2(roundup_pow_of_two(nr_cpu_ids));
+	fc_cpu_mask = (1 << fc_cpu_order) - 1;
 
 	fc_exch_workqueue = create_singlethread_workqueue("fc_exch_workqueue");
 	if (!fc_exch_workqueue)