[DTrace-devel] [PATCH v2 2/2] unittest/sched: remove dtv2 xfail

[Alan Maguire]

On 17/08/2024 01:28, Kris Van Hees wrote:
> Problem found: the OL9 UEK7 kernel I am working with (and possibly all) does
> not allow an FBT probe on __perf_event_task_sched_in.  The failure is silent,
> causing the probe to simply never get enabled and no error reported, so the
> probe does not fire and causes the test to fail.
> 
> In other words... the approach in 1/2 of this series does *not* seem to work
> for OL7 kernels.  That is a problem.
>

Thanks for the report! I've root-caused the absence of the function from
available_filter_functions in UEK7 and earlier (upstream works fine).
Prior to

commit 79df45731da68772d2285265864a52c900b8c65f
Author: Song Liu <songliubraving at fb.com>
Date:   Wed Oct 6 14:07:32 2021 -0700

    perf/core: Allow ftrace for functions in kernel/event/core.c

    It is useful to trace functions in kernel/event/core.c. Allow ftrace for
    them by removing $(CC_FLAGS_FTRACE) from Makefile.

    Signed-off-by: Song Liu <songliubraving at fb.com>
    Signed-off-by: Peter Zijlstra (Intel) <peterz at infradead.org>
    Link:
https://lkml.kernel.org/r/20211006210732.2826289-1-songliubraving@fb.com


...kernel/events/Makefile removed the ftrace compile flags which mark
function entry for the code in kernel/events. In UEK7 we see

ifdef CONFIG_FUNCTION_TRACER
CFLAGS_REMOVE_core.o = $(CC_FLAGS_FTRACE)
endif

I'll try to find a workaround that doesn't rely on function boundary
tracing in these files to work..

Alan

> On Fri, Aug 16, 2024 at 03:33:00PM -0400, Kris Van Hees wrote:
>> Running a full testsuite run (and then also individual test) I found this
>> test to fail on my OL9 VM with 5.15.0-205.149.5.1.el9uek.x86_64 kernel
>> while it works on my Debian VM with a 6.5.0 kernel.
>>
>> On Fri, Aug 02, 2024 at 05:37:11PM -0400, Kris Van Hees wrote:
>>> On Fri, Jun 28, 2024 at 06:16:34PM +0100, Alan Maguire wrote:
>>>> ...since tst.oncpu.d test passes now.
>>>>
>>>> Signed-off-by: Alan Maguire <alan.maguire at oracle.com>
>>>
>>> Reviewed-by: Kris Van Hees <kris.van.hees at oracle.com>
>>>
>>>> ---
>>>>  test/unittest/sched/tst.oncpu.d | 3 +--
>>>>  1 file changed, 1 insertion(+), 2 deletions(-)
>>>>
>>>> diff --git a/test/unittest/sched/tst.oncpu.d b/test/unittest/sched/tst.oncpu.d
>>>> index d2c2ce57..7a33bab4 100644
>>>> --- a/test/unittest/sched/tst.oncpu.d
>>>> +++ b/test/unittest/sched/tst.oncpu.d
>>>> @@ -1,11 +1,10 @@
>>>>  /*
>>>>   * Oracle Linux DTrace.
>>>> - * Copyright (c) 2006, 2020, Oracle and/or its affiliates. All rights reserved.
>>>> + * Copyright (c) 2006, 2024, Oracle and/or its affiliates. All rights reserved.
>>>>   * Licensed under the Universal Permissive License v 1.0 as shown at
>>>>   * http://oss.oracle.com/licenses/upl.
>>>>   */
>>>>  
>>>> -/* @@xfail: dtv2 */
>>>>  /* @@timeout: 15 */
>>>>  
>>>>  #pragma D option switchrate=100hz
>>>> -- 
>>>> 2.43.5
>>>>