Merge master.kernel.org:/pub/scm/linux/kernel/git/jejb/scsi-rc-fixes-2.6

[linux-2.6] / arch / ia64 / kernel / time.c

diff --git a/arch/ia64/kernel/time.c b/arch/ia64/kernel/time.c
index 6c0e9e2e1b82004ba8a9ba70586b76fbb1982899..98cfc90cab1d4916e9664fa01cca00bb41801662 100644 (file)
--- 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();