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This test program tests the features of task isolation.
- Makes sure enabling task isolation fails if you are unaffinitized
or on a non-task-isolation cpu.
- Tests that /sys/devices/system/cpu/task_isolation works correctly.
- Validates that various synchronous exceptions are fatal in isolation
mode:
* Page fault
* System call
* TLB invalidation from another thread [1]
* Unaligned access [2]
- Tests that taking a user-defined signal for the above faults works.
- Tests that isolation in "no signal" mode works as expected: you can
perform multiple system calls without a signal, and if another
process bumps you, you return to userspace without any extra jitter.
[1] TLB invalidations do not cause IPIs on some platforms, e.g. arm64
[2] Unaligned access only causes exceptions on some platforms, e.g. tile
You must be running under a kernel configured with TASK_ISOLATION;
this is available from the "dataplane" branch at:
http://git.kernel.org/cgit/linux/kernel/git/cmetcalf/linux-tile.git/
You must either have configured with TASK_ISOLATION_ALL or else
booted with an argument like "task_isolation=1-15" to enable some
task-isolation cores. If you get interrupts, you can also add
the boot argument "task_isolation_debug" to learn more.
In addition, you must apply the one-line patch in
sched-tick-disable-hack.patch to disable the 1 Hz default tick.
To compile the test program, run "make".
Run the program as "./isolation" and if you want to run the
jitter-detection loop for longer than 10 giga-cycles, specify the
number of giga-cycles to run it for as a command-line argument.
Please send questions and comments to cmetcalf@kernel.org.
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