ZX1 Interrupt latency
Hi Folks,
I've been trying to measure the interrupt latency from PCI bus to
device driver. I've been using a PCI device with a timer that can
trigger an interrupt; I set the timer to go off every 20
microseconds, and measure the pulse width on the interrupt pin.
I'm seeing pulses around 10 microseconds, implying that from the time
the interrupt is asserted to the time the device driver clears the
interrupt on the PCI card is around 10 microseconds.
This seems awfully long to me -- it's a 66MHz PCI bus, and context switch
time on a 900MHz I2 is around 2 microseconds, so I'd expect a latency
around 1 to 2 microseconds.
Does anyone have any ideas of what the minimum latency though the ZX1
chipset *should* be?
2003.12.04- Posted by Peter Chubb
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