On Tue, Jan 12, 2021, Ben Gardon wrote:
> 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 <[email protected]>
> Reviewed-by: Makarand Sonare <[email protected]>
> 
> Signed-off-by: Ben Gardon <[email protected]>
> ---
>  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)

Same comment as earlier.  I vote to let this poke out, or shorten the variables
so that the lines aren't so long.

> +                     ;
> +     }
>  
>       ts_diff = timespec_elapsed(start);
>       pr_info("Populate memory time: %ld.%.9lds\n",
> -- 
> 2.30.0.284.gd98b1dd5eaa7-goog
> 

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