Author: jkim
Date: Wed Dec 8 23:40:41 2010
New Revision: 216312
URL: http://svn.freebsd.org/changeset/base/216312
Log:
Do not subtract 0.5% from estimated frequency if DELAY(9) is driven by TSC.
Remove a confusing comment about converting to MHz as we never did.
Modified:
head/sys/amd64/amd64/machdep.c
head/sys/i386/i386/machdep.c
head/sys/pc98/pc98/machdep.c
Modified: head/sys/amd64/amd64/machdep.c
==============================================================================
--- head/sys/amd64/amd64/machdep.c Wed Dec 8 22:54:18 2010
(r216311)
+++ head/sys/amd64/amd64/machdep.c Wed Dec 8 23:40:41 2010
(r216312)
@@ -563,13 +563,7 @@ cpu_est_clockrate(int cpu_id, uint64_t *
thread_unlock(curthread);
#endif
- /*
- * Calculate the difference in readings, convert to Mhz, and
- * subtract 0.5% of the total. Empirical testing has shown that
- * overhead in DELAY() works out to approximately this value.
- */
- tsc2 -= tsc1;
- *rate = tsc2 * 1000 - tsc2 * 5;
+ *rate = (tsc2 - tsc1) * 1000;
return (0);
}
Modified: head/sys/i386/i386/machdep.c
==============================================================================
--- head/sys/i386/i386/machdep.c Wed Dec 8 22:54:18 2010
(r216311)
+++ head/sys/i386/i386/machdep.c Wed Dec 8 23:40:41 2010
(r216312)
@@ -1157,12 +1157,16 @@ cpu_est_clockrate(int cpu_id, uint64_t *
thread_unlock(curthread);
#endif
+ tsc2 -= tsc1;
+ if (tsc_freq != 0 && !tsc_is_broken) {
+ *rate = tsc2 * 1000;
+ return (0);
+ }
+
/*
- * Calculate the difference in readings, convert to Mhz, and
- * subtract 0.5% of the total. Empirical testing has shown that
+ * Subtract 0.5% of the total. Empirical testing has shown that
* overhead in DELAY() works out to approximately this value.
*/
- tsc2 -= tsc1;
*rate = tsc2 * 1000 - tsc2 * 5;
return (0);
}
Modified: head/sys/pc98/pc98/machdep.c
==============================================================================
--- head/sys/pc98/pc98/machdep.c Wed Dec 8 22:54:18 2010
(r216311)
+++ head/sys/pc98/pc98/machdep.c Wed Dec 8 23:40:41 2010
(r216312)
@@ -1092,12 +1092,16 @@ cpu_est_clockrate(int cpu_id, uint64_t *
thread_unlock(curthread);
#endif
+ tsc2 -= tsc1;
+ if (tsc_freq != 0 && !tsc_is_broken) {
+ *rate = tsc2 * 1000;
+ return (0);
+ }
+
/*
- * Calculate the difference in readings, convert to Mhz, and
- * subtract 0.5% of the total. Empirical testing has shown that
+ * Subtract 0.5% of the total. Empirical testing has shown that
* overhead in DELAY() works out to approximately this value.
*/
- tsc2 -= tsc1;
*rate = tsc2 * 1000 - tsc2 * 5;
return (0);
}
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