KVM: selftests: Introduce the dirty log perf test

The dirty log perf test will time verious dirty logging operations
(enabling dirty logging, dirtying memory, getting the dirty log,
clearing the dirty log, and disabling dirty logging) in order to
quantify dirty logging performance. This test can be used to inform
future performance improvements to KVM's dirty logging infrastructure.

This series was tested by running the following invocations on an Intel
Skylake machine:
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.

Signed-off-by: Ben Gardon <bgardon@google.com>
Message-Id: <20201027233733.1484855-6-bgardon@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/tools/testing/selftests/kvm/lib/test_util.c b/tools/testing/selftests/kvm/lib/test_util.c
index 1a46c2c48c7c..8e04c0b1608e 100644
--- a/tools/testing/selftests/kvm/lib/test_util.c
+++ b/tools/testing/selftests/kvm/lib/test_util.c
@@ -92,6 +92,13 @@ struct timespec timespec_diff_now(struct timespec start)
 	return timespec_sub(end, start);
 }
 
+struct timespec timespec_div(struct timespec ts, int divisor)
+{
+	int64_t ns = timespec_to_ns(ts) / divisor;
+
+	return timespec_add_ns((struct timespec){0}, ns);
+}
+
 void print_skip(const char *fmt, ...)
 {
 	va_list ap;