Author: alfred
Date: Tue Dec 4 05:28:20 2012
New Revision: 243853
URL: http://svnweb.freebsd.org/changeset/base/243853
Log:
replace bit shifting loop with 1<<fls(n), improve comments.
Reviewed by: davide
Modified:
head/sys/kern/kern_timeout.c
Modified: head/sys/kern/kern_timeout.c
==============================================================================
--- head/sys/kern/kern_timeout.c Tue Dec 4 04:37:42 2012
(r243852)
+++ head/sys/kern/kern_timeout.c Tue Dec 4 05:28:20 2012
(r243853)
@@ -84,7 +84,7 @@ SYSCTL_INT(_debug, OID_AUTO, to_avg_mpca
* TODO:
* allocate more timeout table slots when table overflows.
*/
-int callwheelsize, callwheelbits, callwheelmask;
+int callwheelsize, callwheelmask;
/*
* The callout cpu migration entity represents informations necessary for
@@ -218,12 +218,10 @@ kern_timeout_callwheel_alloc(caddr_t v)
timeout_cpu = PCPU_GET(cpuid);
cc = CC_CPU(timeout_cpu);
/*
- * Calculate callout wheel size
+ * Calculate callout wheel size, should be next power of two higher
+ * than 'ncallout'.
*/
- for (callwheelsize = 1, callwheelbits = 0;
- callwheelsize < ncallout;
- callwheelsize <<= 1, ++callwheelbits)
- ;
+ callwheelsize = 1 << fls(ncallout);
callwheelmask = callwheelsize - 1;
cc->cc_callout = (struct callout *)v;
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