On 2023-12-20 06:50, Haibo Xu wrote:
On Wed, Dec 20, 2023 at 2:22 AM Marc Zyngier <maz@xxxxxxxxxx> wrote:
On Tue, 12 Dec 2023 09:31:20 +0000,
Haibo Xu <haibo1.xu@xxxxxxxxx> wrote:
> > @@ -216,6 +221,9 @@ static bool parse_args(int argc, char *argv[])
> case 'm':
> test_args.migration_freq_ms = atoi_non_negative("Frequency", optarg);
> break;
> + case 'e':
> + test_args.timer_err_margin_us = atoi_non_negative("Error Margin", optarg);
> + break;
So your error margin is always unsigned...
The error margin was supposed to be a non-negative [0, INT_MAX].
(May be need to define a Max for the input, instead of INT_MAX)
> case 'o':
> test_args.counter_offset = strtol(optarg, NULL, 0);
> test_args.reserved = 0;
> diff --git a/tools/testing/selftests/kvm/include/timer_test.h b/tools/testing/selftests/kvm/include/timer_test.h
> index 968257b893a7..b1d405e7157d 100644
> --- a/tools/testing/selftests/kvm/include/timer_test.h
> +++ b/tools/testing/selftests/kvm/include/timer_test.h
> @@ -22,6 +22,7 @@ struct test_args {
> int nr_iter;
> int timer_period_ms;
> int migration_freq_ms;
> + int timer_err_margin_us;
... except that you are storing it as a signed value. Some consistency
wouldn't hurt, really, and would avoid issues when passing large
values.
Yes, it's more proper to use an unsigned int for the non-negative error
margin.
Storing as signed here is just to keep the type consistent with that
of timer_period_ms
since there will be '+' operation in other places.
tools/testing/selftests/kvm/aarch64/arch_timer.c
/* Setup a timeout for the interrupt to arrive */
udelay(msecs_to_usecs(test_args.timer_period_ms) +
test_args.timer_err_margin_us);
But that's exactly why using a signed quantity is wrong.
What does it mean to have a huge *negative* margin?
I don't see how you can justify this.
M.
--
Jazz is not dead. It just smells funny...
