Messages in this thread | | | Date | Tue, 11 Dec 2007 16:53:07 +0100 | From | Rene Herman <> | Subject | Re: RFC: outb 0x80 in inb_p, outb_p harmful on some modern AMD64 with MCP51 laptops |
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On 11-12-07 16:37, Paul Rolland wrote:
Great, thanks for the quick replies.
That last one below especially is quite a bit more than 1. As said before, most hardware isn't in fact going to need anything but I suppose udelay(2) might be the "safer" replacement for the outb then...
> On Tue, 11 Dec 2007 16:28:56 +0100 > Rene Herman <rene.herman@keyaccess.nl> wrote: > >> On 11-12-07 15:15, Rene Herman wrote: >> >>> On 11-12-07 14:32, Paul Rolland wrote: >>> >> This might be a bit more constant, I suppose. This serialises with cpuid. >> Don't see a difference locally, but perhaps you do. > Well, yes, at least on the PIII and the Opteron... Core2 is still changing > a lot... > >> On a Duron 1300 with an actual ISA bus, "out" is between 1300 and 1600 for >> me and "in" between 1200 and 1500 with a few flukes above that which will I >> suppose be caused by the bus (ISA _or_ PCI) being momentarily busy or some >> such...
> The results : > > Core 2Duo 1.73 GHz : > [root@tux tmp]# ./in2 > out: 2777 > in : 2519 > [root@tux tmp]# ./in2 > out: 2440 > in : 2391 > [root@tux tmp]# ./in2 > out: 2460 > in : 2388
Okayish I guess, especially when subsequent runs stay near those values.
2500/1730 = 1.45 us
> Pentium III : > [root@www-dev /tmp]# ./in2 > out: 746 > in : 747 > [root@www-dev /tmp]# ./in2 > out: 746 > in : 747 > [root@www-dev /tmp]# ./in2 > out: 746 > in : 745
746/600 ~= 1.24 us
> AMD Opteron 150 : > -bash-3.1# ./in2 > out: 4846 > in : 4845 > -bash-3.1# ./in2 > out: 4846 > in : 4846 > -bash-3.1# ./in2 > out: 4846 > in : 4845
4846 / 2400 = 2.02 us
Rene.
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