Dual Xeon 2.8 with HT - How is the support in FreeBSD 5.3

Achim Patzner ap at bnc.net
Thu Jan 6 13:40:34 PST 2005

Am 06.01.2005 um 22:26 schrieb Julian Elischer:
>> then i wiill try it with HT enabled  and hope for the best.
> The biggest problem is that it will slow your system down..

I'd not agree on this for every available CPU; I just finished some 
extensive test using XEON 3,6 GHz and there is no noticeable difference 
between running the Intel SE7520BD2 with two processors enabled (and HT 
disabled) or one processor and HT. Ok, maybe the board isn't that good 
(it was a severe mistake ordering it as the second NIC (Intel Yukon) is 
wasted space)...

> one of them should be doing Floating Point ops while the other is
> doing integer.. (they share the integer ALU I believe).

Not anymore; the latest XEONs finally have enough brains in their skull.

> There are apps that do ok, but for example compiles get slowed down
> as the virtual CPUs flush each other's cache entries out and contest 
> for the ALU.

Especially doing a "make buildworld" was faster with HT turned on while 
ubench was suffering quite a bit.


PS: I would by those machines again - this time with an SE7520AF 
PPS: Of course they are doing much better runnig an amd64 kernel.

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