Con Kolivas wrote:
On Saturday 18 March 2006 00:26, Nick Piggin wrote:
Con Kolivas wrote:
-static inline void __activate_task(task_t *p, runqueue_t *rq)
+static void __activate_task(task_t *p, runqueue_t *rq)
{
- enqueue_task(p, rq->active);
+ if (batch_task(p))
+ enqueue_task(p, rq->expired);
+ else
+ enqueue_task(p, rq->active);
inc_nr_running(p, rq);
}
I prefer:
prio_array_t *target = rq->active;
if (batch_task(p))
target = rq->expired;
enqueue_task(p, target);
Because gcc can use things like predicated instructions for it.
But perhaps it is smart enough these days to recognise this?
At least in the past I have seen it start using cmov after doing
such a conversion.
At any rate, I think it looks nicer as well. IMO, of course.
Well on my one boring architecture here is a before and after, gcc 4.1.0 with
optimise for size kernel config:
I'm not attached to the style, just the feature. If you think it's warranted
I'll change it.
I guess it isn't doing the cmov because it doesn't want to do the
extra load in the common case, which is fair enough (are you compiling
for a pentiumpro+, without generic x86 support? what about if you
turn off optimise for size?)
At least other archtectures might be able to make better use of it,
and I agree even for i386 the code looks better (and slightly smaller).
--
SUSE Labs, Novell Inc.
Send instant messages to your online friends http://au.messenger.yahoo.com
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
