Re: [PATCH 0/6] KVM: selftests: Perf test cleanups and memslot modification test

From: Paolo Bonzini
Date: Mon Jan 18 2021 - 13:20:44 EST

On 12/01/21 22:42, Ben Gardon wrote:
This series contains a few cleanups that didn't make it into previous
series, including some cosmetic changes and small bug fixes. The series
also lays the groundwork for a memslot modification test which stresses
the memslot update and page fault code paths in an attempt to expose races.

Tested: dirty_log_perf_test, memslot_modification_stress_test, and
demand_paging_test were run, with all the patches in this series
applied, on an Intel Skylake machine.

echo Y > /sys/module/kvm/parameters/tdp_mmu; \
./memslot_modification_stress_test -i 1000 -v 64 -b 1G; \
./memslot_modification_stress_test -i 1000 -v 64 -b 64M -o; \
./dirty_log_perf_test -v 64 -b 1G; \
./dirty_log_perf_test -v 64 -b 64M -o; \
./demand_paging_test -v 64 -b 1G; \
./demand_paging_test -v 64 -b 64M -o; \
echo N > /sys/module/kvm/parameters/tdp_mmu; \
./memslot_modification_stress_test -i 1000 -v 64 -b 1G; \
./memslot_modification_stress_test -i 1000 -v 64 -b 64M -o; \
./dirty_log_perf_test -v 64 -b 1G; \
./dirty_log_perf_test -v 64 -b 64M -o; \
./demand_paging_test -v 64 -b 1G; \
./demand_paging_test -v 64 -b 64M -o

The tests behaved as expected, and fixed the problem of the
population stage being skipped in dirty_log_perf_test. This can be
seen in the output, with the population stage taking about the time
dirty pass 1 took and dirty pass 1 falling closer to the times for
the other passes.

Note that when running these tests, the -o option causes the test to take
much longer as the work each vCPU must do increases proportional to the
number of vCPUs.

You can view this series in Gerrit at:

Ben Gardon (6):
KVM: selftests: Rename timespec_diff_now to timespec_elapsed
KVM: selftests: Avoid flooding debug log while populating memory
KVM: selftests: Convert iterations to int in dirty_log_perf_test
KVM: selftests: Fix population stage in dirty_log_perf_test
KVM: selftests: Add option to overlap vCPU memory access
KVM: selftests: Add memslot modification stress test

tools/testing/selftests/kvm/.gitignore | 1 +
tools/testing/selftests/kvm/Makefile | 1 +
.../selftests/kvm/demand_paging_test.c | 40 +++-
.../selftests/kvm/dirty_log_perf_test.c | 72 +++---
.../selftests/kvm/include/perf_test_util.h | 4 +-
.../testing/selftests/kvm/include/test_util.h | 2 +-
.../selftests/kvm/lib/perf_test_util.c | 25 ++-
tools/testing/selftests/kvm/lib/test_util.c | 2 +-
.../kvm/memslot_modification_stress_test.c | 211 ++++++++++++++++++
9 files changed, 307 insertions(+), 51 deletions(-)
create mode 100644 tools/testing/selftests/kvm/memslot_modification_stress_test.c

Queued, thanks.