Allocate additional space for latency samples. This has been separated
out to call attention to the additional VM memory allocation. The test
runs out of physical pages without the additional allocation. The 100
multiple for pages was determined by trial and error. A more
well-reasoned calculation would be preferable.
Signed-off-by: Colton Lewis <coltonlewis@xxxxxxxxxx>
---
tools/testing/selftests/kvm/lib/perf_test_util.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/kvm/lib/perf_test_util.c b/tools/testing/selftests/kvm/lib/perf_test_util.c
index 137be359b09e..a48904b64e19 100644
--- a/tools/testing/selftests/kvm/lib/perf_test_util.c
+++ b/tools/testing/selftests/kvm/lib/perf_test_util.c
@@ -38,6 +38,12 @@ static bool all_vcpu_threads_running;
static struct kvm_vcpu *vcpus[KVM_MAX_VCPUS];
+#define SAMPLES_PER_VCPU 1000
+#define SAMPLE_CAPACITY (SAMPLES_PER_VCPU * KVM_MAX_VCPUS)
+
+/* Store all samples in a flat array so they can be easily sorted later. */
+uint64_t latency_samples[SAMPLE_CAPACITY];
+
/*
* Continuously write to the first 8 bytes of each page in the
* specified region.
@@ -122,7 +128,7 @@ struct kvm_vm *perf_test_create_vm(enum vm_guest_mode mode, int nr_vcpus,
{
struct perf_test_args *pta = &perf_test_args;
struct kvm_vm *vm;
- uint64_t guest_num_pages, slot0_pages = 0;
+ uint64_t guest_num_pages, sample_pages, slot0_pages = 0;
uint64_t backing_src_pagesz = get_backing_src_pagesz(backing_src);
uint64_t region_end_gfn;
int i;
@@ -161,7 +167,9 @@ struct kvm_vm *perf_test_create_vm(enum vm_guest_mode mode, int nr_vcpus,
* The memory is also added to memslot 0, but that's a benign side
* effect as KVM allows aliasing HVAs in meslots.
*/
- vm = __vm_create_with_vcpus(mode, nr_vcpus, slot0_pages + guest_num_pages,
+ sample_pages = 100 * sizeof(latency_samples) / pta->guest_page_size;
+ vm = __vm_create_with_vcpus(mode, nr_vcpus,
+ slot0_pages + guest_num_pages + sample_pages,
perf_test_guest_code, vcpus);
pta->vm = vm;
--
2.38.1.431.g37b22c650d-goog
