Re: Real-Time Preemption, -RT-2.6.12-final-V0.7.50-24

William Weston
2005-07-01T01:02:00Z

On Thu, 30 Jun 2005, William Weston wrote:
> On Fri, 1 Jul 2005, Karsten Wiese wrote:
> > --- linux-2.6.12-RT-50-35/arch/i386/kernel/mpparse.c 2005-06-30 16:38:00.000000000 +0200
> > +++ linux-2.6.12-RT/arch/i386/kernel/mpparse.c 2005-06-29 20:30:50.000000000 +0200
> > @@ -263,6 +263,7 @@
> > return;
> > }
> > mp_ioapics[nr_ioapics] = *m;
> > + io_apic_base[nr_ioapics] = IO_APIC_BASE(nr_ioapics);
> > nr_ioapics++;
> > }
> >
> > @@ -914,6 +915,7 @@
> > mp_ioapics[idx].mpc_apicaddr = address;
> >
> > set_fixmap_nocache(FIX_IO_APIC_BASE_0 + idx, address);
> > + io_apic_base[idx] = IO_APIC_BASE(idx);
> > mp_ioapics[idx].mpc_apicid = io_apic_get_unique_id(idx, id);
> > mp_ioapics[idx].mpc_apicver = io_apic_get_version(idx);
>
> Thanks, Karsten. This patch was needed to get my Xeon/HT (i865) to boot
> -50-39. Next I'll see if IOAPIC_FAST will work. I'll keep you posted.

After applying this patch to -50-39, IOAPIC_FAST now works on both the
Xeon/HT and the non-HT Xeon boxes (i865 and i845 respectively). Wakeup
latencies are looking better, especially on the Xeon/HT (max of 53us so
far, as compared to 183us with -50-37 without IOAPIC_FAST).

I'll test this out on the Athlon box (which hasn't done well with
IOAPIC_FAST previously) when I get home.

--ww