On Tue, Apr 9, 2024 at 6:39 AM Oleg Nesterov <oleg@xxxxxxxxxx> wrote:
>
> Thomas says:
>
> The signal distribution test has a tendency to hang for a long
> time as the signal delivery is not really evenly distributed. In
> fact it might never be distributed across all threads ever in
> the way it is written.
>
> To me even the
>
> This primarily tests that the kernel does not favour any one.
>
> comment doesn't look right. The kernel does favour a thread which hits
> the timer interrupt when CLOCK_PROCESS_CPUTIME_ID expires.
>
> The new version simply checks that the group leader sleeping in join()
> never receives SIGALRM, cpu_timer_fire() should always send the signal
> to the thread which burns cpu.
>
> Without the commit bcb7ee79029d ("posix-timers: Prefer delivery of signals
> to the current thread") the test-case fails immediately, the very 1st tick
> wakes the leader up. Otherwise it quickly succeeds after 100 ticks.
>
> As Thomas suggested, the new version doesn't report the failure on the
> pre v6.3 kernels that do not have the commit bcb7ee79029d; this is a
> feature that obviously fails on the older kernels. So the patch adds the
> new simple ksft_ck_kernel_version() helper and uses ksft_test_result_skip()
> if check_timer_distribution() fails on the older kernel.
>
> Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
This is working great here (on both 6.6 and the older 6.1)! Thanks so
much for fixing this!
One nit below, but otherwise:
Tested-by: John Stultz <jstultz@xxxxxxxxxx>
> +err:
> + ksft_print_msg(errmsg);
This bit is causing the following warning:
posix_timers.c:250:2: warning: format not a string literal and no
format arguments [-Wformat-security]
250 | ksft_print_msg(errmsg);
| ^~~~~~~~~~~~~~
A simple fix is just to switch it to:
ksft_print_msg("%s", errmsg);
thanks
-john
