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Date: Thu, 26 Nov 2009 19:18:41 -0700
To: Manolis Kiagias <sonicy@otenet.gr>
From: Brett Glass <brett@lariat.net>
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Cc: questions@freebsd.org
Subject: HTT on Atom (Was: FreeBSD 8.0 and Atheros AzureWave wireless
 chipset)
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At 04:33 PM 11/26/2009, Manolis Kiagias wrote:

>Though it seems hyperthreading is improved on the Atom and there is no
>penalty for leaving it on.

Is there really no penalty? With HZ=1000 there are double the clock 
interrupts to be serviced at least. And as I understand it the Atom 
has less redundant hardware, so there are less likely to be unused 
resources available to the second thread. I am seeing substantially 
faster compiles with the SMP option commented out of the kernel.

--Brett