linux-kernel - [PATCH 4/6] KVM: selftests: Fix population stage in dirty_log_perf

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Date:   Tue, 12 Jan 2021 13:42:51 -0800
From:   Ben Gardon <bgardon@...gle.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        linux-kselftest@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>, Peter Xu <peterx@...hat.com>,
        Andrew Jones <drjones@...hat.com>,
        Peter Shier <pshier@...gle.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Thomas Huth <thuth@...hat.com>, Jacob Xu <jacobhxu@...gle.com>,
        Makarand Sonare <makarandsonare@...gle.com>,
        Ben Gardon <bgardon@...gle.com>
Subject: [PATCH 4/6] KVM: selftests: Fix population stage in dirty_log_perf_test

Currently the population stage in the dirty_log_perf_test does nothing
as the per-vCPU iteration counters are not initialized and the loop does
not wait for each vCPU. Remedy those errors.

Reviewed-by: Jacob Xu <jacobhxu@...gle.com>
Reviewed-by: Makarand Sonare <makarandsonare@...gle.com>

Signed-off-by: Ben Gardon <bgardon@...gle.com>
---
 tools/testing/selftests/kvm/dirty_log_perf_test.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/kvm/dirty_log_perf_test.c b/tools/testing/selftests/kvm/dirty_log_perf_test.c
index 3875f22d7283..fb6eb7fa0b45 100644
--- a/tools/testing/selftests/kvm/dirty_log_perf_test.c
+++ b/tools/testing/selftests/kvm/dirty_log_perf_test.c
@@ -139,14 +139,19 @@ static void run_test(enum vm_guest_mode mode, void *arg)
 
 	clock_gettime(CLOCK_MONOTONIC, &start);
 	for (vcpu_id = 0; vcpu_id < nr_vcpus; vcpu_id++) {
+		vcpu_last_completed_iteration[vcpu_id] = -1;
+
 		pthread_create(&vcpu_threads[vcpu_id], NULL, vcpu_worker,
 			       &perf_test_args.vcpu_args[vcpu_id]);
 	}
 
-	/* Allow the vCPU to populate memory */
+	/* Allow the vCPUs to populate memory */
 	pr_debug("Starting iteration %d - Populating\n", iteration);
-	while (READ_ONCE(vcpu_last_completed_iteration[vcpu_id]) != iteration)
-		;
+	for (vcpu_id = 0; vcpu_id < nr_vcpus; vcpu_id++) {
+		while (READ_ONCE(vcpu_last_completed_iteration[vcpu_id]) !=
+		       iteration)
+			;
+	}
 
 	ts_diff = timespec_elapsed(start);
 	pr_info("Populate memory time: %ld.%.9lds\n",
-- 
2.30.0.284.gd98b1dd5eaa7-goog