* [PATCH -rt] cycles_to_usecs rounding fix
[not found] <20071212201258.890003246@mvista.com>
@ 2007-12-12 20:15 ` Daniel Walker
0 siblings, 0 replies; only message in thread
From: Daniel Walker @ 2007-12-12 20:15 UTC (permalink / raw)
To: rostedt; +Cc: mingo, linux-kernel, linux-rt-users, johnstul
do_div() rounds down, so we add have the divisor to round up. This effected my
change to preempt_max_latency. Each time you read preempt_max_latency it gets
rounded lower.
Signed-off-by: Daniel Walker <dwalker@mvista.com>
---
kernel/time/timekeeping.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
Index: linux-2.6.23/kernel/time/timekeeping.c
===================================================================
--- linux-2.6.23.orig/kernel/time/timekeeping.c
+++ linux-2.6.23/kernel/time/timekeeping.c
@@ -144,7 +144,8 @@ unsigned long notrace cycles_to_usecs(cy
{
u64 ret = cyc2ns(clock, cycles);
- do_div(ret, 1000);
+ ret += NSEC_PER_USEC/2; /* For rounding in do_div() */
+ do_div(ret, NSEC_PER_USEC);
return ret;
}
--
--
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[not found] <20071212201258.890003246@mvista.com>
2007-12-12 20:15 ` [PATCH -rt] cycles_to_usecs rounding fix Daniel Walker
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