[PATCH v2 02/16] KVM: selftests: Add optional delay between consecutive clear-dirty-log calls

From: Vipin Sharma
Date: Fri Jun 02 2023 - 12:09:33 EST


In dirty_log_perf_test, add option "-l" to wait between consecutive
clear-dirty-log calls. Accept delay from user in milliseconds. If option
is not provided then fallback to no wait between clear calls.

This allows dirty_log_perf_test to mimic real world use where after
clearing dirty memory, some time is spent in transferring memory before
making a subsequeunt clear-dirty-log call.

Signed-off-by: Vipin Sharma <vipinsh@xxxxxxxxxx>
---
.../selftests/kvm/dirty_log_perf_test.c | 35 +++++++++++++++----
1 file changed, 29 insertions(+), 6 deletions(-)

diff --git a/tools/testing/selftests/kvm/dirty_log_perf_test.c b/tools/testing/selftests/kvm/dirty_log_perf_test.c
index 119ddfc7306e..2e31f13aaba6 100644
--- a/tools/testing/selftests/kvm/dirty_log_perf_test.c
+++ b/tools/testing/selftests/kvm/dirty_log_perf_test.c
@@ -135,6 +135,7 @@ struct test_params {
uint32_t random_seed;
bool random_access;
uint64_t clear_chunk_size;
+ int clear_chunk_wait_time_ms;
};

static void toggle_dirty_logging(struct kvm_vm *vm, int slots, bool enable)
@@ -173,8 +174,14 @@ static void get_dirty_log(struct kvm_vm *vm, unsigned long *bitmaps[], int slots
static void clear_dirty_log_in_chunks(struct kvm_vm *vm,
unsigned long *bitmaps[], int slots,
uint64_t pages_per_slot,
- uint64_t pages_per_clear)
+ uint64_t pages_per_clear, int wait_ms,
+ struct timespec *time_taken)
{
+ struct timespec wait = {
+ .tv_sec = wait_ms / 1000,
+ .tv_nsec = (wait_ms % 1000) * 1000000ull,
+ };
+ struct timespec start, end;
uint64_t from, clear_pages_count;
int i, slot;

@@ -186,12 +193,17 @@ static void clear_dirty_log_in_chunks(struct kvm_vm *vm,
while (from < pages_per_slot) {
if (from + clear_pages_count > pages_per_slot)
clear_pages_count = pages_per_slot - from;
+ clock_gettime(CLOCK_MONOTONIC, &start);
kvm_vm_clear_dirty_log(vm, slot, bitmaps[i], from,
clear_pages_count);
+ end = timespec_elapsed(start);
+ *time_taken = timespec_add(*time_taken, end);
from += clear_pages_count;
+ if (wait_ms)
+ nanosleep(&wait, NULL);
+
}
}
-
}

static unsigned long **alloc_bitmaps(int slots, uint64_t pages_per_slot)
@@ -329,11 +341,11 @@ static void run_test(enum vm_guest_mode mode, void *arg)
iteration, ts_diff.tv_sec, ts_diff.tv_nsec);

if (dirty_log_manual_caps) {
- clock_gettime(CLOCK_MONOTONIC, &start);
clear_dirty_log_in_chunks(vm, bitmaps, p->slots,
pages_per_slot,
- pages_per_clear);
- ts_diff = timespec_elapsed(start);
+ pages_per_clear,
+ p->clear_chunk_wait_time_ms,
+ &ts_diff);
clear_dirty_log_total = timespec_add(clear_dirty_log_total,
ts_diff);
pr_info("Iteration %d clear dirty log time: %ld.%.9lds\n",
@@ -435,6 +447,11 @@ static void help(char *name)
" the memslot size then whole memslot is cleared in one call.\n"
" Size must be aligned to the host page size. e.g. 10M or 3G\n"
" (default: UINT64_MAX, clears whole memslot in one call)\n");
+ printf(" -l: Specify time in milliseconds to wait after Clear-Dirty-Log\n"
+ " call. This allows to mimic use cases where flow is to get\n"
+ " dirty log followed by multiple clear dirty log calls and\n"
+ " sending corresponding memory to destination (in this test\n"
+ " sending will be just idle waiting)\n");
puts("");
exit(0);
}
@@ -451,6 +468,7 @@ int main(int argc, char *argv[])
.random_seed = 1,
.write_percent = 100,
.clear_chunk_size = UINT64_MAX,
+ .clear_chunk_wait_time_ms = 0,
};
int opt;

@@ -461,7 +479,7 @@ int main(int argc, char *argv[])

guest_modes_append_default();

- while ((opt = getopt(argc, argv, "ab:c:eghi:k:m:nop:r:s:v:x:w:")) != -1) {
+ while ((opt = getopt(argc, argv, "ab:c:eghi:k:l:m:nop:r:s:v:x:w:")) != -1) {
switch (opt) {
case 'a':
p.random_access = true;
@@ -488,6 +506,11 @@ int main(int argc, char *argv[])
case 'k':
p.clear_chunk_size = parse_size(optarg);
break;
+ case 'l':
+ p.clear_chunk_wait_time_ms =
+ atoi_non_negative("Clear dirty log chunks wait time",
+ optarg);
+ break;
case 'm':
guest_modes_cmdline(optarg);
break;
--
2.41.0.rc0.172.g3f132b7071-goog