Linear access through all pages does not seem to replicate performance
problems with realistic dirty logging workloads. Make the test more
sophisticated through random access. Each vcpu has its own sequence of
random numbers that are refilled after every iteration. Having the
main thread fill the table for every vcpu is less efficient than
having each vcpu generate its own numbers, but this ensures threading
nondeterminism won't destroy reproducibility with a given random seed.
Signed-off-by: Colton Lewis <coltonlewis@xxxxxxxxxx>
---
.../selftests/kvm/dirty_log_perf_test.c | 13 ++++-
.../selftests/kvm/include/perf_test_util.h | 4 ++
.../selftests/kvm/lib/perf_test_util.c | 47 +++++++++++++++++++
3 files changed, 63 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/kvm/dirty_log_perf_test.c b/tools/testing/selftests/kvm/dirty_log_perf_test.c
index f99e39a672d3..80a1cbe7fbb0 100644
--- a/tools/testing/selftests/kvm/dirty_log_perf_test.c
+++ b/tools/testing/selftests/kvm/dirty_log_perf_test.c
@@ -132,6 +132,7 @@ struct test_params {
bool partition_vcpu_memory_access;
enum vm_mem_backing_src_type backing_src;
int slots;
+ uint32_t random_seed;
};
static void toggle_dirty_logging(struct kvm_vm *vm, int slots, bool enable)
@@ -243,6 +244,10 @@ static void run_test(enum vm_guest_mode mode, void *arg)
/* Start the iterations */
iteration = 0;
host_quit = false;
+ srandom(p->random_seed);
+ pr_info("Random seed: %d\n", p->random_seed);
+ alloc_random_table(nr_vcpus, guest_percpu_mem_size >> vm->page_shift);
+ fill_random_table(nr_vcpus, guest_percpu_mem_size >> vm->page_shift);
clock_gettime(CLOCK_MONOTONIC, &start);
for (i = 0; i < nr_vcpus; i++)
@@ -270,6 +275,7 @@ static void run_test(enum vm_guest_mode mode, void *arg)
ts_diff.tv_sec, ts_diff.tv_nsec);
while (iteration < p->iterations) {
+ fill_random_table(nr_vcpus, guest_percpu_mem_size >> vm->page_shift);
/*
* Incrementing the iteration number will start the vCPUs
* dirtying memory again.
@@ -380,6 +386,7 @@ static void help(char *name)
printf(" -v: specify the number of vCPUs to run.\n");
printf(" -o: Overlap guest memory accesses instead of partitioning\n"
" them into a separate region of memory for each vCPU.\n");
+ printf(" -r: specify the starting random seed.\n");
backing_src_help("-s");
printf(" -x: Split the memory region into this number of memslots.\n"
" (default: 1)\n");
@@ -396,6 +403,7 @@ int main(int argc, char *argv[])
.partition_vcpu_memory_access = true,
.backing_src = DEFAULT_VM_MEM_SRC,
.slots = 1,
+ .random_seed = time(NULL),
};
int opt;
@@ -406,7 +414,7 @@ int main(int argc, char *argv[])
guest_modes_append_default();
- while ((opt = getopt(argc, argv, "eghi:p:m:nb:f:v:os:x:")) != -1) {
+ while ((opt = getopt(argc, argv, "eghi:p:m:nb:f:v:or:s:x:")) != -1) {
switch (opt) {
case 'e':
/* 'e' is for evil. */
@@ -442,6 +450,9 @@ int main(int argc, char *argv[])
case 'o':
p.partition_vcpu_memory_access = false;
break;
+ case 'r':
+ p.random_seed = atoi(optarg);
+ break;
case 's':
p.backing_src = parse_backing_src_type(optarg);
break;
diff --git a/tools/testing/selftests/kvm/include/perf_test_util.h b/tools/testing/selftests/kvm/include/perf_test_util.h
index eaa88df0555a..597875d0c3db 100644
--- a/tools/testing/selftests/kvm/include/perf_test_util.h
+++ b/tools/testing/selftests/kvm/include/perf_test_util.h
@@ -44,6 +44,10 @@ struct perf_test_args {
};
extern struct perf_test_args perf_test_args;
+extern uint32_t **random_table;
+
+void alloc_random_table(uint32_t nr_vcpus, uint32_t nr_randoms);
+void fill_random_table(uint32_t nr_vcpus, uint32_t nr_randoms);
struct kvm_vm *perf_test_create_vm(enum vm_guest_mode mode, int nr_vcpus,
uint64_t vcpu_memory_bytes, int slots,
diff --git a/tools/testing/selftests/kvm/lib/perf_test_util.c b/tools/testing/selftests/kvm/lib/perf_test_util.c
index 9618b37c66f7..b04e8d2c0f37 100644
--- a/tools/testing/selftests/kvm/lib/perf_test_util.c
+++ b/tools/testing/selftests/kvm/lib/perf_test_util.c
@@ -9,6 +9,10 @@
#include "processor.h"
struct perf_test_args perf_test_args;
+/* This pointer points to guest memory and must be converted with
+ * addr_gva2hva to be accessed from the host.
+ */
+uint32_t **random_table;
/*
* Guest virtual memory offset of the testing memory slot.
@@ -70,6 +74,49 @@ void perf_test_guest_code(uint32_t vcpu_idx)
}
}
+void alloc_random_table(uint32_t nr_vcpus, uint32_t nr_randoms)
+{
+ struct perf_test_args *pta = &perf_test_args;
+ uint32_t **host_random_table;
+
+ random_table = (uint32_t **)vm_vaddr_alloc(
+ pta->vm,
+ nr_vcpus * sizeof(uint32_t *),
+ (vm_vaddr_t)0);
+ host_random_table = addr_gva2hva(pta->vm, (vm_vaddr_t)random_table);
+ pr_debug("Random start addr: %p %p.\n", random_table, host_random_table);
+
+ for (uint32_t i = 0; i < nr_vcpus; i++) {
+ host_random_table[i] = (uint32_t *)vm_vaddr_alloc(
+ pta->vm,
+ nr_randoms * sizeof(uint32_t),
+ (vm_vaddr_t)0);
+ pr_debug("Random row addr: %p %p.\n",
+ host_random_table[i],
+ addr_gva2hva(pta->vm, (vm_vaddr_t)host_random_table[i]));
+ }
+}
+
+void fill_random_table(uint32_t nr_vcpus, uint32_t nr_randoms)
+{
+ struct perf_test_args *pta = &perf_test_args;
+ uint32_t **host_random_table = addr_gva2hva(pta->vm, (vm_vaddr_t)random_table);
+ uint32_t *host_row;
+
+ pr_debug("Random start addr: %p %p.\n", random_table, host_random_table);
+
+ for (uint32_t i = 0; i < nr_vcpus; i++) {
+ host_row = addr_gva2hva(pta->vm, (vm_vaddr_t)host_random_table[i]);
+ pr_debug("Random row addr: %p %p.\n", host_random_table[i], host_row);
+
+ for (uint32_t j = 0; j < nr_randoms; j++)
+ host_row[j] = random();
+
+ pr_debug("New randoms row %d: %d, %d, %d...\n",
+ i, host_row[0], host_row[1], host_row[2]);
+ }
+}
+
void perf_test_setup_vcpus(struct kvm_vm *vm, int nr_vcpus,
struct kvm_vcpu *vcpus[],
uint64_t vcpu_memory_bytes,
--
2.37.1.559.g78731f0fdb-goog
