On Thu, Mar 30, 2000 at 10:05:26AM -0800, Mike Smith wrote:
> > >> Just following on from this, one thing that I can see immediately being
> > >> very important to me at least is a spinlock in the timecounter structure.
> > >> Calcru and various other things call microtime(), and we're going to want
> > >> to lock out updates and parallel accesses to the timecounter. What
> > >> should we be using for an interrupt-disabling spinlock?
> > >
> > >Nothing. Accesses to the timecounter struct are already MP safe and fast.
> > >Only the i8254 timecounter hardware currently needs interrupt-disabling,
> > >but it is hopefully never used on SMP machines.
> >
> > Worse. It is used by default on SMP machines which don't sport the
> > PIIX timecounter.
>
> ie. anything using the PIIX3 or older (think 440FX dual P6 systems, etc.)
On the box below, a relative new dual PIII box, with a Intel
motherboard, does it use the i8254 or the PIIX timecounter ?
Copyright (c) 1992-2000 The FreeBSD Project.
Copyright (c) 1982, 1986, 1989, 1991, 1993
The Regents of the University of California. All rights reserved.
FreeBSD 4.0-STABLE #0: Mon Mar 27 17:02:42 CEST 2000
root@:/usr/src/sys/compile/REMIE
Timecounter "i8254" frequency 1193182 Hz
CPU: Pentium III/Pentium III Xeon (496.66-MHz 686-class CPU)
Origin = "GenuineIntel" Id = 0x672 Stepping = 2
Features=0x387fbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,PN,MMX,FXSR,XMM>
real memory = 268369920 (262080K bytes)
config> q
avail memory = 257515520 (251480K bytes)
Programming 24 pins in IOAPIC #0
IOAPIC #0 intpin 2 -> irq 0
FreeBSD/SMP: Multiprocessor motherboard
cpu0 (BSP): apic id: 1, version: 0x00040011, at 0xfee00000
cpu1 (AP): apic id: 0, version: 0x00040011, at 0xfee00000
io0 (APIC): apic id: 2, version: 0x00170011, at 0xfec00000
Preloaded elf kernel "kernel" at 0xc02c5000.
Preloaded userconfig_script "/boot/kernel.conf" at 0xc02c509c.
Pentium Pro MTRR support enabled
md0: Malloc disk
npx0: <math processor> on motherboard
npx0: INT 16 interface
pcib0: <Intel 82443BX host to PCI bridge (AGP disabled)> on motherboard
pci0: <PCI bus> on pcib0
[snip]
isab0: <Intel 82371AB PCI to ISA bridge> at device 18.0 on pci0
isa0: <ISA bus> on isab0
pci0: <Intel PIIX4 ATA controller> at 18.1
pci0: <Intel 82371AB/EB (PIIX4) USB controller> at 18.2 irq 10
Timecounter "PIIX" frequency 3579545 Hz
/Jesper
--
Jesper Skriver, jesper(at)skriver(dot)dk - CCIE #5456
Work: Network manager @ AS3292 (Tele Danmark DataNetworks)
Private: Geek @ AS2109 (A much smaller network ;-)
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