The patch that I sent before had wrong numbers in it, it could result in
"Clocksource jiffies might overflow on 11% adjustment" message. This is
the patch with correct numbers.
> +#if HZ < 30
> +#define JIFFIES_SHIFT 6
> +#elif HZ < 60
> +#define JIFFIES_SHIFT 7
> +#else
> #define JIFFIES_SHIFT 8
> +#endif
From: Mikulas Patocka <mpato...@redhat.com>
Fix overflow when HZ is 32
When compiling for the IA-64 ski emulator, HZ is set to 32 because the
emulation is slow and we don't want to waste too many cycles processing
timers. Alpha also has an option to set HZ to 32.
This causes integer underflow in
kernel/time/jiffies.c:
kernel/time/jiffies.c:66:2: warning: large integer implicitly truncated to
unsigned type [-Woverflow]
.mult = NSEC_PER_JIFFY << JIFFIES_SHIFT, /* details above */
^
This patch reduces the JIFFIES_SHIFT value to avoid the overflow.
Signed-off-by: Mikulas Patocka <miku...@artax.karlin.mff.cuni.cz>
Cc: sta...@vger.kernel.org
---
kernel/time/jiffies.c | 6 ++++++
1 file changed, 6 insertions(+)
Index: linux-2.6-ia64/kernel/time/jiffies.c
===================================================================
--- linux-2.6-ia64.orig/kernel/time/jiffies.c 2014-01-24 22:34:17.000000000
+0100
+++ linux-2.6-ia64/kernel/time/jiffies.c 2014-01-24 22:36:56.000000000
+0100
@@ -51,7 +51,13 @@
* HZ shrinks, so values greater than 8 overflow 32bits when
* HZ=100.
*/
+#if HZ < 34
+#define JIFFIES_SHIFT 6
+#elif HZ < 67
+#define JIFFIES_SHIFT 7
+#else
#define JIFFIES_SHIFT 8
+#endif
static cycle_t jiffies_read(struct clocksource *cs)
{
--
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