[Linux-ia64] [PATCH] fix timer interrupts getting lost

[Alex Williamson <alex_williamson@attbi.com>]

[-- Attachment #1: Type: text/plain, Size: 402 bytes --]


    This patch fixes the issue of some CPUs not showing timer interrupts
going off.  Seems during the process of sync'ing the itc, we jumped over
the next timer value.  This patch is against 2.5.67 + ia64.  I haven't
seen the problem on 2.4, but a quick looks seems like it's potentially
an issue there too.  Thanks,

	Alex

--
Alex Williamson                             HP Linux and Open Source Lab

[-- Attachment #2: smp_timer_fix.diff --]
[-- Type: text/plain, Size: 523 bytes --]

--- linux-2.5.67.clean/arch/ia64/kernel/smpboot.c	2003-04-22 13:58:09.000000000 -0600
+++ linux-2.5.67/arch/ia64/kernel/smpboot.c	2003-04-23 20:25:00.000000000 -0600
@@ -311,6 +311,15 @@
 		 */
 		Dprintk("Going to syncup ITC with BP.\n");
 		ia64_sync_itc(0);
+
+		/*
+		 * Make sure we didn't sync the itc ahead of the next
+		 * timer interrupt, if so, just reset it.
+		 */
+		if (time_after(ia64_get_itc(),local_cpu_data->itm_next)) {
+			Dprintk("oops, jumped a timer.\n");
+			ia64_cpu_local_tick();
+		}
 	}
 
 	/*