		  Linux Interrupt Latency benchmark

	--| Description |--

This Linux kernel module measure the latency of the interrupt handler.
It generate an interrupt and account how many CPU tick Linux eat in order
to launch the irq handler.

	--| Compilation |--

-  Edit `./Makefile' and set the KERNEL variable to point to a writable linux
   source tree. You need a writable copy of it since the compilation stage
   need to only `touch` something.
-  Run `make`.

	--| Running |--

To run the benchmark you must `insmod` the module specifying as module
parameter the number of the hardware irq line in which generate the hardware
interrupt. For example something like this:

	# insmod ./lil.o irq=3

will generate an irq on the line 3. The irq number _must_ be >=0 and <= 15
since the irq is generated playing with the 8259 that handle only the first
16 interrupt. To read the benchmark results you must run `dmesg`.

	--| Technical details |--

The trick I use to generate the hardware interrupt is to trigger the
edge/level register of the 8259 irq controller so this module is really
i386 specific and not portable. Also the accounting of the time is not
portable due the use of the `rdtsc' asm instruction.

	--| $Id: README,v 1.5 1998/08/17 13:18:27 andrea Exp $ |--
