HEADS UP [Re: thread+preemption stability improvement]

[Daniel Eriksson]

> I have set aside some time on the server (normally a busy 
> production-type
> server) to try a few different configs (SHED_ULE instead of SHED_4BSD,
> turning off apic, removing polling) to see if any of them 
> will have any
> impact.

I have just tried a number of different combinations of sheduler, acpi,
apic, polling, ...

No matter what I do, the only way to prevent errors like the one below seems
to be to run with preemption turned off.

Interrupt storm detected on "irq20: atapci4"; throttling interrupt source
ad20: FAILURE - already active DMA on this device
ad20: setting up DMA failed

See my recent mail on this list entitled "Kernel preemption leads to SATA
instability (how to debug?)" for machine configuration and further
information.

/Daniel Eriksson