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

[Karsten Wiese <annabellesgarden@yahoo.de>]

Am Donnerstag, 30. Juni 2005 22:50 schrieb Ingo Molnar:
> 
> * Karsten Wiese <annabellesgarden@yahoo.de> wrote:
> 
> > Here come some numbers to back up the usefullness of 
> > CONFIG_X86_UP_IOAPIC_FAST. (and to show that my patch actually works 
> > ;-)) All measurement where taken on an UP Athlon64 2Ghz running 32bit 
> > 2.6.12-RT-50-35 PREEMPT_RT on a K8T800 mobo.
> 
> thanks - the numbers are pretty convincing. I've applied most of your 
> patch (except the instrumentation bits), and it seems to work quite well 
> - one of my testsystems that had interrupt storms before can now run 
> IOAPIC_FAST. (i also enabled the option to be selectable for SMP kernels 
> too. If things work out fine we can make it default-on.) I've uploaded 
> the -50-39 patch with these changes included.
> 
Ooops, you didn't apply this part of the patch:

<snip>
--- 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);
</snip>

It provides the precalculation of the ioapics's virtual address.
Or does IO_APIC_BASE() compile to an indexed lookup?
 then io_apic_base[] wouldn't be needed...

Karsten

	

	
		
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