Con Kolivas wrote:
On Saturday 04 March 2006 17:50, Mike Galbraith wrote:
On Sat, 2006-03-04 at 16:54 +1100, Con Kolivas wrote:
On Saturday 04 March 2006 16:40, Randy.Dunlap wrote:
On Sat, 04 Mar 2006 06:29:47 +0100 Mike Galbraith wrote:
On Sat, 2006-03-04 at 16:24 +1100, Con Kolivas wrote:
On Saturday 04 March 2006 16:20, Mike Galbraith wrote:
On Sat, 2006-03-04 at 13:33 +1100, Peter Williams wrote:
include/linux/sched.h | 3 -
kernel/sched.c | 136
+++++++++++++++++++++++++++++--------------------- 2 files
changed, 82 insertions(+), 57 deletions(-)
--- linux-2.6.16-rc5-mm2/include/linux/sched.h.org 2006-03-01
15:06:22.000000000 +0100 +++
linux-2.6.16-rc5-mm2/include/linux/sched.h 2006-03-02
08:33:12.000000000 +0100 @@ -720,7 +720,8 @@
unsigned long policy;
cpumask_t cpus_allowed;
- unsigned int time_slice, first_time_slice;
+ int time_slice;
Can you guarantee that int is big enough to hold a time slice
in nanoseconds on all systems? I think that you'll need more
than 16 bits.
Nope, that's a big fat bug.
Most ints are 32bit anyway, but even a 32 bit unsigned int
overflows with nanoseconds at 4.2 seconds. A signed one at about
half that. Our timeslices are never that large, but then int isn't
always 32bit either.
Yup. I just didn't realize that there were 16 bit integers out
there.
LDD 3rd ed. doesn't know about them either. Same for me.
Alright I made that up, but it might not be one day :P
Well Fudgecicles. Now you guys have gotten me aaaaall confused. Are
there cpus out there (in generic linux land) that have 16 bit integers
or not? 16 bit integers existing in a 32 bit cpu OS seems like an alien
concept to me, but I'm not a twisted cpu designer... I'll just go with
the flow ;-)
All supported architectures on linux currently use 32bits for int. That should
give you 2.1 seconds in nanoseconds. Sorry my legacy of remembering when ints
were 8 bits coloured me.
Cheers,
Con
The size of int isn't just a function of the architecture it's also a
function of the C compiler used. C requires that longs be at least 32
bits but only requires that ints be at least 16 bits. If the
architecture supports 16 bit integer operations there's nothing to stop
a VALID compiler from make ints only 16 bits. Since everyone uses gcc
(at the moment) it's probably not an (urgent) issue but it seems to me
that the safe option is to use longs when you want to ensure that you
get at least 32 bits.
Peter
--
Peter Williams [email protected]
"Learning, n. The kind of ignorance distinguishing the studious."
-- Ambrose Bierce
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