Re: FreeBSD Security Advisory FreeBSD-SA-05:09.htt [REVISED]

"Poul-Henning Kamp" <phk@phk.freebsd.dk> writes:
> The correct (technical) workaround (IMO) is to restrict HTT to be
> used only for threads from the same process.
>
> The political problem is that if all operating systems do that,
> Intel has a pretty dud feature on their hands, and they are not
> particularly eager to accept that fact.

No.  Intel themselves recommend only scheduling threads from the same
address space on the same physical core, simply because it improves
cache efficiency.  Scheduling threads from separate processes on the
same physical core can actually *reduce* performance due to cache
churn.  Fixing our scheduler to avoid scheduling threads from
different processes on the same physical core is likely to increase
performance across the board, because heavily multithreaded software
will get a bigger boost and single-threaded software will be penalized
less than it is today.

DES
--=20
Dag-Erling Sm=F8rgrav - des@des.no
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