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-rw-r--r--arch/ia64/kernel/time.c16
1 files changed, 15 insertions, 1 deletions
diff --git a/arch/ia64/kernel/time.c b/arch/ia64/kernel/time.c
index 6c0e9e2e1b82..98cfc90cab1d 100644
--- a/arch/ia64/kernel/time.c
+++ b/arch/ia64/kernel/time.c
@@ -240,7 +240,21 @@ ia64_init_itm (void)
if (!nojitter)
itc_jitter_data.itc_jitter = 1;
#endif
- }
+ } else
+ /*
+ * ITC is drifty and we have not synchronized the ITCs in smpboot.c.
+ * ITC values may fluctuate significantly between processors.
+ * Clock should not be used for hrtimers. Mark itc as only
+ * useful for boot and testing.
+ *
+ * Note that jitter compensation is off! There is no point of
+ * synchronizing ITCs since they may be large differentials
+ * that change over time.
+ *
+ * The only way to fix this would be to repeatedly sync the
+ * ITCs. Until that time we have to avoid ITC.
+ */
+ clocksource_itc.rating = 50;
/* Setup the CPU local timer tick */
ia64_cpu_local_tick();