linux-stable/tools/testing
Sean Christopherson 7b0035eaa7 KVM: selftests: Ensure all migrations are performed when test is affined
Rework the CPU selection in the migration worker to ensure the specified
number of migrations are performed when the test iteslf is affined to a
subset of CPUs.  The existing logic skips iterations if the target CPU is
not in the original set of possible CPUs, which causes the test to fail
if too many iterations are skipped.

  ==== Test Assertion Failure ====
  rseq_test.c:228: i > (NR_TASK_MIGRATIONS / 2)
  pid=10127 tid=10127 errno=4 - Interrupted system call
     1  0x00000000004018e5: main at rseq_test.c:227
     2  0x00007fcc8fc66bf6: ?? ??:0
     3  0x0000000000401959: _start at ??:?
  Only performed 4 KVM_RUNs, task stalled too much?

Calculate the min/max possible CPUs as a cheap "best effort" to avoid
high runtimes when the test is affined to a small percentage of CPUs.
Alternatively, a list or xarray of the possible CPUs could be used, but
even in a horrendously inefficient setup, such optimizations are not
needed because the runtime is completely dominated by the cost of
migrating the task, and the absolute runtime is well under a minute in
even truly absurd setups, e.g. running on a subset of vCPUs in a VM that
is heavily overcommited (16 vCPUs per pCPU).

Fixes: 61e52f1630 ("KVM: selftests: Add a test for KVM_RUN+rseq to detect task migration bugs")
Reported-by: Dongli Zhang <dongli.zhang@oracle.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210929234112.1862848-1-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2021-09-30 04:25:57 -04:00
..
fault-injection
ktest bootconfig/tracing/ktest: Update ktest example for boot-time tracing 2021-08-16 11:39:51 -04:00
kunit kunit: Print test statistics on failure 2021-08-13 13:38:31 -06:00
nvdimm tools/testing/nvdimm: Fix missing 'fallthrough' warning 2021-08-11 11:55:54 -07:00
radix-tree idr test suite: Improve reporting from idr_find_test_1 2021-04-01 07:50:42 -04:00
scatterlist Merge branch 'akpm' (patches from Andrew) 2021-09-03 10:08:28 -07:00
selftests KVM: selftests: Ensure all migrations are performed when test is affined 2021-09-30 04:25:57 -04:00
vsock vsock_test: update message bounds test for MSG_EOR 2021-09-06 02:25:16 -04:00