Messages in this thread | | | Subject | Re: [patch] prefer TSC over PM Timer | From | john stultz <> | Date | Tue, 16 Nov 2004 01:50:44 -0800 |
| |
On Mon, 2004-11-15 at 19:21 -0800, dean gaudet wrote: > On Mon, 15 Nov 2004, john stultz wrote: > > With your patch, ACPI PM would never be selected (as TSC always wins > > when available, and it will be available on all ACPI enabled i386 > > systems). So its just the same as disabling CONFIG_X86_PM_TIMER, so why > > not just do that? > > my patch lets you use "clock=pmtmr" if you want it.
Yea, but at that point you have to enable it in the config and then pass a boot parameter to use it. I dunno. If you want to go with that you should def include a comment in the pmtmr code as well as in the config help.
> > Do note, using the "clock=tsc" boot option, you can easily force the > > system to use the TSC. > > right -- except i think the default is the opposite of what it should be > for a generic kernel. i think more systems are served better by using tsc > than those that need clock=pm... NUMA systems are rare (with custom > kernels/etc), and if my experience with the centrino is valid then newer > laptops aren't having this tsc/cpufreq problem. > > > I would however, support a patch that selected the TSC over the ACPI PM > > time source when CONFIG_CPUFREQ and CONFIG_SMP were N. That's fairly > > safe. > > i'm looking for a solution that generic distribution kernels can use... > > honestly my selfish motivation is to get efficeon/crusoe treated properly > -- they support a fixed TSC rate which does not vary with frequency (which > many people fault us for, but the reality is that fixed TSC is the only > viable solution for a processor which can vary power consumption without > the involvement of the kernel).
Yea, I just wish we could get away from the TSC and have a well defined and hardware guaranteed timebase register like PPC.
> i'd advocate a patch like the one > below... but it feels wrong.
Yea, no, I definitely don't like that. I know how these tricks work, send out a worse patch to make the first look better ;) But alas, you've worn me down! Add the comments I mentioned above and I'd go along with it.
Dominik: are you cool with this?
thanks -john
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |