only one logical CPU used in Xeon

Oliver Fromme olli at
Tue Mar 17 05:31:18 PDT 2009

won.derick at wrote:
 > John Baldwin wrote:
 > > in the ULE case (though the sysctl doesn't work).  If
 > > you use 4BSD on 7.1 
 > > then the tunable and sysctl will work fine.
 > > 
 > I tried this, but I can't see the variable being displayed.

Then your machine doesn't support hyperthreading.

The machdep.hyperthreading_allowed sysctl is only present
if your machine actually has multiple logical CPUs.
If you don't see that sysctl, then your processor doesn't
have multiple hyperthreaded CPUs.

If you're interested how this is done in the source, see the
function cpu_hlt_setup() in src/sys/amd64/amd64/mp_machdep.c
or src/sys/i386/i386/mp_machdep.c, respectively.

Best regards

Oliver Fromme, secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing b. M.
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secnetix Verwaltungsgesellsch. mbH, Handelsregister: Registergericht Mün-
chen, HRB 125758,  Geschäftsführer: Maik Bachmann, Olaf Erb, Ralf Gebhart

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