Currently KVM lacks a simple, userspace agnostic, performance benchmark for dirty logging. Such a benchmark will be beneficial for ensuring that dirty logging performance does not regress, and to give a common baseline for validating performance improvements. The dirty log perf test introduced in this series builds on aspects of the existing demand paging perf test and provides time-based performance metrics for enabling and disabling dirty logging, getting the dirty log, and dirtying memory.
While the test currently only has a build target for x86, I expect it will work on, or be easily modified to support other architectures.
This series was tested by running the following invocations on an Intel Skylake machine after apply all commits in the series: dirty_log_perf_test -b 20m -i 100 -v 64 dirty_log_perf_test -b 20g -i 5 -v 4 dirty_log_perf_test -b 4g -i 5 -v 32 demand_paging_test -b 20m -v 64 demand_paging_test -b 20g -v 4 demand_paging_test -b 4g -v 32 All behaved as expected.
v1 -> v2 changes: (in response to comments from Peter Xu) - Removed pr_debugs from main test thread while waiting on vCPUs to reduce log spam - Fixed a bug in iteration counting that caused the population stage to be counted as part of the first dirty logging pass - Fixed a bug in which the test failed to wait for the population stage for all but the first vCPU. - Refactored the common code in perf_test_util.c/h - Moved testing description to cover letter - Renamed timespec_diff_now to timespec_elapsed
Ben Gardon (5): KVM: selftests: Remove address rounding in guest code KVM: selftests: Factor code out of demand_paging_test KVM: selftests: Simplify demand_paging_test with timespec_diff_now KVM: selftests: Add wrfract to common guest code KVM: selftests: Introduce the dirty log perf test
tools/testing/selftests/kvm/.gitignore | 1 + tools/testing/selftests/kvm/Makefile | 7 +- .../selftests/kvm/demand_paging_test.c | 231 ++--------- .../selftests/kvm/dirty_log_perf_test.c | 381 ++++++++++++++++++ .../selftests/kvm/include/perf_test_util.h | 51 +++ .../testing/selftests/kvm/include/test_util.h | 2 + .../selftests/kvm/lib/perf_test_util.c | 166 ++++++++ tools/testing/selftests/kvm/lib/test_util.c | 22 +- 8 files changed, 661 insertions(+), 200 deletions(-) create mode 100644 tools/testing/selftests/kvm/dirty_log_perf_test.c create mode 100644 tools/testing/selftests/kvm/include/perf_test_util.h create mode 100644 tools/testing/selftests/kvm/lib/perf_test_util.c