New interrupt code slows hyperthreading down

Jens Rehsack rehsack at
Fri Nov 7 07:53:48 PST 2003


I recompiled my system today and when it came up again,
it was terrible slow. Using top I've seen, that there're
around 25% cpu-time is used to handle interrupts.
The kernel was configured using SMP ('cause it's a HTT
enabled CPU) and APIC. Setting machdep.hlt_logical_cpus
to 1 didn't change anything. Simply getting a few mails
(around 30) takes about 20 minutes. Most of time while
getting the mails my mozilla was in "*Giant" state,
what shouldn't be good, should it?

I've recompiled the kernel without SMP and APIC and
now the system's behaviour is more "normal". Is the
behaviour of the new interrupt code better on real
multiprocessor systems?

Jens Rehsack

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