Re: get_cycles() on i386

[Nick Piggin]

Linus Torvalds wrote:

> On 4 Nov 2003, john stultz wrote:
>
> > CONFIG_X86_TSC be the devil. Personally, I'd much prefer dropping the
> > compile time option and using dynamic detection. Something like (not
> > recently tested and i believe against 2.5.something, but you get the
> > idea):
>
> Some of the users are really timing-critical (eg scheduler).

The scheduler uses its own sched_clock which only gives jiffies
resolution if CONFIG_NUMA is defined. Unfortunate because I think
its interactive behaviour isn't so good with ms resolution.

The scheduler does not need to have synchronised TSCs though, I think.
It just means 2 more calls to sched_clock in a slow path (smp migration).


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/