[PATCH 24/26] staging/lustre/lprocfs: implement log2 using bitops

Peng Tao
2013-11-14T16:46:09Z

From: Andrew Perepechko <andrew_perepechko@xyratex.com>

This patch implements log2 using fls.

Reviewed-by: alexander_zarochentsev@xyratex.com
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-3496
Signed-off-by: Andrew Perepechko <andrew_perepechko@xyratex.com>
Reviewed-by: Alexander Boyko <Alexander_Boyko@xyratex.com>
Reviewed-by: Vitaly Fertman <Vitaly_Fertman@xyratex.com>
Lustre-change: http://review.whamcloud.com/6757
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Peng Tao <bergwolf@gmail.com>
Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
---
.../lustre/lustre/obdclass/lprocfs_status.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c b/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c
index 428a023..b2647c8 100644
--- a/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c
+++ b/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c
@@ -1961,10 +1961,10 @@ EXPORT_SYMBOL(lprocfs_oh_tally);

void lprocfs_oh_tally_log2(struct obd_histogram *oh, unsigned int value)
{
- unsigned int val;
+ unsigned int val = 0;

- for (val = 0; ((1 << val) < value) && (val <= OBD_HIST_MAX); val++)
- ;
+ if (likely(value != 0))
+ val = min(fls(value - 1), OBD_HIST_MAX);

lprocfs_oh_tally(oh, val);
}
--
1.7.9.5