Make time-backwarsd warning a run-time configurable option.

Signed-off-by: Keir Fraser <keir@xensource.com>

diff --git a/linux-2.6-xen-sparse/arch/i386/kernel/time-xen.c b/linux-2.6-xen-sparse/arch/i386/kernel/time-xen.c
index fd3c627045aaa158e12d071fff96846cef240611..ee5bbe160fc79029e2ca5c5a4b657f42ef9cbbce 100644 (file)
--- a/linux-2.6-xen-sparse/arch/i386/kernel/time-xen.c
+++ b/linux-2.6-xen-sparse/arch/i386/kernel/time-xen.c
@@ -157,6 +157,15 @@ static int __init __independent_wallclock(char *str)
 }
 __setup("independent_wallclock", __independent_wallclock);
 
+/* Permitted clock jitter, in usecs, beyond which a warning will be printed. */
+static unsigned long permitted_clock_jitter = 10000UL;
+static int __init __permitted_clock_jitter(char *str)
+{
+       permitted_clock_jitter = simple_strtoul(str, NULL, 0);
+       return 1;
+}
+__setup("permitted_clock_jitter=", __permitted_clock_jitter);
+
 int tsc_disable __devinitdata = 0;
 
 static void delay_tsc(unsigned long loops)
@@ -632,7 +641,8 @@ irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
                } while (sched_time != runstate->state_entry_time);
        } while (!time_values_up_to_date(cpu));
 
-       if ((unlikely(delta < -1000000LL) || unlikely(delta_cpu < 0))
+       if ((unlikely(delta < -(s64)permitted_clock_jitter) ||
+            unlikely(delta_cpu < -(s64)permitted_clock_jitter))
            && printk_ratelimit()) {
                printk("Timer ISR/%d: Time went backwards: "
                       "delta=%lld cpu_delta=%lld shadow=%lld "
@@ -1037,13 +1047,31 @@ void local_teardown_timer(unsigned int cpu)
  * now however.
  */
 static ctl_table xen_subtable[] = {
-       {1, "independent_wallclock", &independent_wallclock,
-        sizeof(independent_wallclock), 0644, NULL, proc_dointvec},
-       {0}
+       {
+               .ctl_name       = 1,
+               .procname       = "independent_wallclock",
+               .data           = &independent_wallclock,
+               .maxlen         = sizeof(independent_wallclock),
+               .mode           = 0644,
+               .proc_handler   = proc_dointvec
+       },
+       {
+               .ctl_name       = 2,
+               .procname       = "permitted_clock_jitter",
+               .data           = &permitted_clock_jitter,
+               .maxlen         = sizeof(permitted_clock_jitter),
+               .mode           = 0644,
+               .proc_handler   = proc_doulongvec_minmax
+       },
+       { 0 }
 };
 static ctl_table xen_table[] = {
-       {123, "xen", NULL, 0, 0555, xen_subtable},
-       {0}
+       {
+               .ctl_name       = 123,
+               .procname       = "xen",
+               .mode           = 0555,
+               .child          = xen_subtable},
+       { 0 }
 };
 static int __init xen_sysctl_init(void)
 {