linux/tools
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
..
accounting
arch KVM: selftests: Remove __NR_userfaultfd syscall fallback 2021-09-22 10:24:02 -04:00
bootconfig tools/bootconfig: Define memblock_free_ptr() to fix build error 2021-09-15 09:49:48 -07:00
bpf Merge https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2021-07-31 11:23:26 -07:00
build perf cs-etm: Update OpenCSD decoder for ETE 2021-09-03 08:16:00 -03:00
cgroup
debugging tools: Fix "the the" in a message in kernel-chktaint 2021-06-13 17:01:17 -06:00
edid
firewire
firmware
gpio
hv
iio
include tools: compiler-gcc.h: Guard error attribute use with __has_attribute 2021-09-13 15:51:41 -07:00
io_uring tools/io_uring/io_uring-cp: sync with liburing example 2021-08-13 08:58:11 -06:00
kvm/kvm_stat
laptop
leds
lib libperf evsel: Make use of FD robust. 2021-09-18 17:43:06 -03:00
memory-model tools/memory-model: Document data_race(READ_ONCE()) 2021-07-27 11:48:55 -07:00
objtool A single ELF format fix for a section flags mismatch bug that breaks 2021-06-28 11:35:55 -07:00
pci tools: PCI: Zero-initialize param 2021-08-05 11:01:30 +01:00
pcmcia
perf perf bpf: Ignore deprecation warning when using libbpf's btf__get_from_id() 2021-09-18 17:47:02 -03:00
power tools/power/x86/intel-speed-select: v1.10 release 2021-06-18 15:29:32 +02:00
rcu
scripts tools build: Fix quiet cmd indentation 2021-05-17 12:10:03 +09:00
spi
testing KVM: selftests: Ensure all migrations are performed when test is affined 2021-09-30 04:25:57 -04:00
thermal/tmon tools/thermal/tmon: Add cross compiling support 2021-08-14 15:33:19 +02:00
time
tracing
usb
virtio tools/virtio: fix build 2021-08-11 06:44:24 -04:00
vm tools/vm/page_owner_sort.c: check malloc() return 2021-06-29 10:53:47 -07:00
wmi
Makefile