KVM: selftests: Simplify demand_paging_test with timespec_diff_now

Add a helper function to get the current time and return the time since
a given start time. Use that function to simplify the timekeeping in the
demand paging test.

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: <20201027233733.1484855-4-bgardon@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/tools/testing/selftests/kvm/demand_paging_test.c b/tools/testing/selftests/kvm/demand_paging_test.c
index 4251e98..7de6feb 100644 (file)
--- a/tools/testing/selftests/kvm/demand_paging_test.c
+++ b/tools/testing/selftests/kvm/demand_paging_test.c
@@ -50,7 +50,8 @@ static void *vcpu_worker(void *data)
        int vcpu_id = vcpu_args->vcpu_id;
        struct kvm_vm *vm = perf_test_args.vm;
        struct kvm_run *run;
-       struct timespec start, end, ts_diff;
+       struct timespec start;
+       struct timespec ts_diff;
 
        vcpu_args_set(vm, vcpu_id, 1, vcpu_id);
        run = vcpu_state(vm, vcpu_id);
@@ -66,8 +67,7 @@ static void *vcpu_worker(void *data)
                            exit_reason_str(run->exit_reason));
        }
 
-       clock_gettime(CLOCK_MONOTONIC, &end);
-       ts_diff = timespec_sub(end, start);
+       ts_diff = timespec_diff_now(start);
        PER_VCPU_DEBUG("vCPU %d execution time: %ld.%.9lds\n", vcpu_id,
                       ts_diff.tv_sec, ts_diff.tv_nsec);
 
@@ -78,7 +78,7 @@ static int handle_uffd_page_request(int uffd, uint64_t addr)
 {
        pid_t tid;
        struct timespec start;
-       struct timespec end;
+       struct timespec ts_diff;
        struct uffdio_copy copy;
        int r;
 
@@ -98,10 +98,10 @@ static int handle_uffd_page_request(int uffd, uint64_t addr)
                return r;
        }
 
-       clock_gettime(CLOCK_MONOTONIC, &end);
+       ts_diff = timespec_diff_now(start);
 
        PER_PAGE_DEBUG("UFFDIO_COPY %d \t%ld ns\n", tid,
-                      timespec_to_ns(timespec_sub(end, start)));
+                      timespec_to_ns(ts_diff));
        PER_PAGE_DEBUG("Paged in %ld bytes at 0x%lx from thread %d\n",
                       perf_test_args.host_page_size, addr, tid);
 
@@ -123,7 +123,8 @@ static void *uffd_handler_thread_fn(void *arg)
        int pipefd = uffd_args->pipefd;
        useconds_t delay = uffd_args->delay;
        int64_t pages = 0;
-       struct timespec start, end, ts_diff;
+       struct timespec start;
+       struct timespec ts_diff;
 
        clock_gettime(CLOCK_MONOTONIC, &start);
        while (!quit_uffd_thread) {
@@ -192,8 +193,7 @@ static void *uffd_handler_thread_fn(void *arg)
                pages++;
        }
 
-       clock_gettime(CLOCK_MONOTONIC, &end);
-       ts_diff = timespec_sub(end, start);
+       ts_diff = timespec_diff_now(start);
        PER_VCPU_DEBUG("userfaulted %ld pages over %ld.%.9lds. (%f/sec)\n",
                       pages, ts_diff.tv_sec, ts_diff.tv_nsec,
                       pages / ((double)ts_diff.tv_sec + (double)ts_diff.tv_nsec / 100000000.0));
@@ -257,7 +257,8 @@ static void run_test(enum vm_guest_mode mode, bool use_uffd,
        pthread_t *vcpu_threads;
        pthread_t *uffd_handler_threads = NULL;
        struct uffd_handler_args *uffd_args = NULL;
-       struct timespec start, end, ts_diff;
+       struct timespec start;
+       struct timespec ts_diff;
        int *pipefds = NULL;
        struct kvm_vm *vm;
        int vcpu_id;
@@ -335,9 +336,9 @@ static void run_test(enum vm_guest_mode mode, bool use_uffd,
                PER_VCPU_DEBUG("Joined thread for vCPU %d\n", vcpu_id);
        }
 
-       pr_info("All vCPU threads joined\n");
+       ts_diff = timespec_diff_now(start);
 
-       clock_gettime(CLOCK_MONOTONIC, &end);
+       pr_info("All vCPU threads joined\n");
 
        if (use_uffd) {
                char c;
@@ -351,7 +352,6 @@ static void run_test(enum vm_guest_mode mode, bool use_uffd,
                }
        }
 
-       ts_diff = timespec_sub(end, start);
        pr_info("Total guest execution time: %ld.%.9lds\n",
                ts_diff.tv_sec, ts_diff.tv_nsec);
        pr_info("Overall demand paging rate: %f pgs/sec\n",

diff --git a/tools/testing/selftests/kvm/include/test_util.h b/tools/testing/selftests/kvm/include/test_util.h
index 5eb01bf..1cc036d 100644 (file)
--- a/tools/testing/selftests/kvm/include/test_util.h
+++ b/tools/testing/selftests/kvm/include/test_util.h
@@ -64,5 +64,6 @@ int64_t timespec_to_ns(struct timespec ts);
 struct timespec timespec_add_ns(struct timespec ts, int64_t ns);
 struct timespec timespec_add(struct timespec ts1, struct timespec ts2);
 struct timespec timespec_sub(struct timespec ts1, struct timespec ts2);
+struct timespec timespec_diff_now(struct timespec start);
 
 #endif /* SELFTEST_KVM_TEST_UTIL_H */

diff --git a/tools/testing/selftests/kvm/lib/test_util.c b/tools/testing/selftests/kvm/lib/test_util.c
index 689e97c..1a46c2c 100644 (file)
--- a/tools/testing/selftests/kvm/lib/test_util.c
+++ b/tools/testing/selftests/kvm/lib/test_util.c
@@ -4,10 +4,13 @@
  *
  * Copyright (C) 2020, Google LLC.
  */
-#include <stdlib.h>
+
+#include <assert.h>
 #include <ctype.h>
 #include <limits.h>
-#include <assert.h>
+#include <stdlib.h>
+#include <time.h>
+
 #include "test_util.h"
 
 /*
@@ -81,6 +84,14 @@ struct timespec timespec_sub(struct timespec ts1, struct timespec ts2)
        return timespec_add_ns((struct timespec){0}, ns1 - ns2);
 }
 
+struct timespec timespec_diff_now(struct timespec start)
+{
+       struct timespec end;
+
+       clock_gettime(CLOCK_MONOTONIC, &end);
+       return timespec_sub(end, start);
+}
+
 void print_skip(const char *fmt, ...)
 {
        va_list ap;