README

  1This directory contains a mix of tests integrated with kselftest and
  2standalone stress tests.
  3
  4kselftest tests
  5===============
  6
  7sve-probe-vls - Checks the SVE vector length enumeration interface
  8sve-ptrace - Checks the SVE ptrace interface
  9
 10Running the non-kselftest tests
 11===============================
 12
 13sve-stress performs an SVE context switch stress test, as described
 14below.
 15
 16(The fpsimd-stress test works the same way; just substitute "fpsimd" for
 17"sve" in the following commands.)
 18
 19
 20The test runs until killed by the user.
 21
 22If no context switch error was detected, you will see output such as
 23the following:
 24
 25$ ./sve-stress
 26(wait for some time)
 27^C
 28Vector length:        512 bits
 29PID:    1573
 30Terminated by signal 15, no error, iterations=9467, signals=1014
 31Vector length:  512 bits
 32PID:    1575
 33Terminated by signal 15, no error, iterations=9448, signals=1028
 34Vector length:  512 bits
 35PID:    1577
 36Terminated by signal 15, no error, iterations=9436, signals=1039
 37Vector length:  512 bits
 38PID:    1579
 39Terminated by signal 15, no error, iterations=9421, signals=1039
 40Vector length:  512 bits
 41PID:    1581
 42Terminated by signal 15, no error, iterations=9403, signals=1039
 43Vector length:  512 bits
 44PID:    1583
 45Terminated by signal 15, no error, iterations=9385, signals=1036
 46Vector length:  512 bits
 47PID:    1585
 48Terminated by signal 15, no error, iterations=9376, signals=1039
 49Vector length:  512 bits
 50PID:    1587
 51Terminated by signal 15, no error, iterations=9361, signals=1039
 52Vector length:  512 bits
 53PID:    1589
 54Terminated by signal 15, no error, iterations=9350, signals=1039
 55
 56
 57If an error was detected, details of the mismatch will be printed
 58instead of "no error".
 59
 60Ideally, the test should be allowed to run for many minutes or hours
 61to maximise test coverage.
 62
 63
 64KVM stress testing
 65==================
 66
 67To try to reproduce the bugs that we have been observing, sve-stress
 68should be run in parallel in two KVM guests, while simultaneously
 69running on the host.
 70
 711) Start 2 guests, using the following command for each:
 72
 73$ lkvm run --console=virtio -pconsole=hvc0 --sve Image
 74
 75(Depending on the hardware GIC implementation, you may also need
 76--irqchip=gicv3.  New kvmtool defaults to that if appropriate, but I
 77can't remember whether my branch is new enough for that.  Try without
 78the option first.)
 79
 80Kvmtool occupies the terminal until you kill it (Ctrl+A x),
 81or until the guest terminates.  It is therefore recommended to run
 82each instance in separate terminal (use screen or ssh etc.)  This
 83allows multiple guests to be run in parallel while running other
 84commands on the host.
 85
 86Within the guest, the host filesystem is accessible, mounted on /host.
 87
 882) Run the sve-stress on *each* guest with the Vector-Length set to 32:
 89guest$ ./vlset --inherit 32 ./sve-stress
 90
 913) Run the sve-stress on the host with the maximum Vector-Length:
 92host$ ./vlset --inherit --max ./sve-stress
 93
 94
 95Again, the test should be allowed to run for many minutes or hours to
 96maximise test coverage.
 97
 98If no error is detected, you will see output from each sve-stress
 99instance similar to that illustrated above; otherwise details of the
100observed mismatches will be printed.