Messages in this thread |  | | Date | Sun, 22 Oct 2000 11:49:47 +1100 | From | Andrew Morton <> | Subject | Re: lowish-lat for 2.4.0-test10-pre3 |
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Andi Kleen wrote: > > On Sun, Oct 22, 2000 at 12:58:00AM +1100, Andrew Morton wrote: > > reschedule: > > + sti > > call SYMBOL_NAME(schedule) # test > > The sti can be removed because one of the first things schedule() does is a > sti [forgot to mention that earlier]
Yup. But it's the rare path and I was being paranoid :)
schedule() actually does *two* sti's. One is open-coded in the tq scheduler code and the other is subtly buried inside release_kernel_lock(). It should be hoisted right up to the start of the function.
BTW: regarding this comment:
> On the Mendocino the `cli' adds ~15 cycles to system calls. The > cunning removal of a conditional jump from the syscall and interrupt > fastpath reduces this to 13 cycles. > > So `getpid()' now takes 1.005x as long as it used to. So shoot me.
The arithmetic was wrong. 22nSec on 530nSec is 1.04x. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/
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