Attachment 317538 Details for Bug 463573 – Fix false softlockup warnings

[patch] Fix false softlockup warnings

fix-lockup-warnings-for64bit.patch (text/plain), 2.50 KB, created by Alok Kataria on 2008-09-23 21:38:07 UTC

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Creator: Alok Kataria

Created: 2008-09-23 21:38:07 UTC

Size: 2.50 KB

patch

obsolete

>Fix false softlockups.
>
>From: Alok N Kataria <akataria@vmware.com>
>
>With the new clocksource driver on a hypervisor, we can see time and
>jiffies jumping around by more than 10secs, depending on the time the vcpu
>was descheduled. As a result we may see spurious softlockups.
>This patch fixes those by touching the softlockup time stamps whenever
>there are such time jumps.
>
>Signed-off-by: Alok N Kataria <akataria@vmware.com>
>---
>
> arch/x86_64/kernel/time.c |   23 ++++++++++++++++++++++-
> 1 files changed, 22 insertions(+), 1 deletions(-)
>
>
>diff --git a/arch/x86_64/kernel/time.c b/arch/x86_64/kernel/time.c
>index 3bf6012..9dcf36f 100644
>--- a/arch/x86_64/kernel/time.c
>+++ b/arch/x86_64/kernel/time.c
>@@ -95,6 +95,7 @@ struct timezone __sys_tz __section_sys_tz;
> /* -1=>disabled, 0=>autoconfigure, 1=>enabled */
> static int timekeeping_use_tsc;
> static cycles_t cycles_per_jiffy, cycles_accounted_limit;
>+static cycles_t cycles_softlockup_limit;
> 
> extern unsigned long preset_lpj;
> /*
>@@ -451,8 +452,9 @@ static void do_timer_account_lost_ticks(struct pt_regs *regs)
>  */
> static void do_timer_tsc_timekeeping(struct pt_regs *regs)
> {
>-	int i;
>+	int i, reset_softlockup = 0;
> 	cycles_t tsc, tsc_accounted, tsc_not_accounted;
>+	cycles_t tsc_softlockup_accounted = 0;
> 
> 	tsc = get_cycles_sync();
> 	tsc_accounted = vxtime.last_tsc;
>@@ -468,11 +470,26 @@ static void do_timer_tsc_timekeeping(struct pt_regs *regs)
> 		tsc_not_accounted = cycles_accounted_limit;
> 	}
> 
>+#ifdef CONFIG_DETECT_SOFTLOCKUP
>+	if (tsc_not_accounted >= cycles_softlockup_limit) {
>+		reset_softlockup = 1;
>+		tsc_softlockup_accounted = cycles_softlockup_limit;
>+		touch_all_softlockup_watchdogs();
>+	}
>+#endif
>+
> 	while (tsc_not_accounted >= cycles_per_jiffy) {
> 		for (i = 0; i < tick_divider; i++)
> 			do_timer(regs);
> 		tsc_not_accounted -= cycles_per_jiffy;
> 		tsc_accounted += cycles_per_jiffy;
>+		if (unlikely(reset_softlockup)) {
>+			tsc_softlockup_accounted -= cycles_per_jiffy;
>+			if (!tsc_softlockup_accounted) {
>+				touch_all_softlockup_watchdogs();
>+				tsc_softlockup_accounted = cycles_softlockup_limit;
>+			}
>+		}
> 	}
> 
> 	monotonic_base += ((tsc_accounted - vxtime.last_tsc) *
>@@ -1086,6 +1103,10 @@ void __init time_init(void)
> 		 * timer interrupt is 10 minutes.
> 		 */
> 		cycles_accounted_limit = cycles_per_jiffy * HZ * 60 * 10;
>+#ifdef CONFIG_DETECT_SOFTLOCKUP
>+		cycles_softlockup_limit = cycles_per_jiffy * HZ *
>+					  (softlockup_thresh - 1);
>+#endif
> 		tick_nsec = NSEC_PER_SEC / HZ;
> 		printk(KERN_INFO
> 			"time.c: Using tsc for timekeeping HZ %d\n", HZ);

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