On 10/02/2022 06:00, Steven Rostedt wrote:
> On Wed, 9 Feb 2022 17:24:30 +0100
> Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxxxxx> wrote:
>
>> The PREEMPT_RT patchset does not use soft IRQs thus trying to filter for
>> do_softirq fails for such kernel:
>>
>> echo do_softirq
>> ftracetest: 81: echo: echo: I/O error
>>
>> Choose some other externally visible function for the test.
>>
>> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxxxxx>
>>
>> ---
>>
>> I understand that the failure does not exist on mainline kernel (only
>> with PREEMPT_RT patchset) but the change does not harm it.
>>
>> If it is not suitable alone, please consider it for RT patchset.
>> ---
>> .../selftests/ftrace/test.d/ftrace/func_set_ftrace_file.tc | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/tools/testing/selftests/ftrace/test.d/ftrace/func_set_ftrace_file.tc b/tools/testing/selftests/ftrace/test.d/ftrace/func_set_ftrace_file.tc
>> index e96e279e0533..1d0c7601865f 100644
>> --- a/tools/testing/selftests/ftrace/test.d/ftrace/func_set_ftrace_file.tc
>> +++ b/tools/testing/selftests/ftrace/test.d/ftrace/func_set_ftrace_file.tc
>> @@ -19,7 +19,7 @@ fail() { # mesg
>>
>> FILTER=set_ftrace_filter
>> FUNC1="schedule"
>> -FUNC2="do_softirq"
>> +FUNC2="_printk"
>
> The problem with the above, is that it is not guaranteed to trigger (and
> probably will not), where as the do_softirq is. The filtering is suppose to
> trace something that actually happens.
>
> How about using: scheduler_tick ?
>
This works as well. I had impression that the test is only about
filtering interface and actual function does not have to hit/trigger.
I'll send v2 with scheduler_tick.
Best regards,
Krzysztof
