From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Cc: Steven Rostedt <rostedt@goodmis.org>,
Ingo Molnar <mingo@redhat.com>, Shuah Khan <shuah@kernel.org>,
linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-rt-users@vger.kernel.org, joseph.salisbury@canonical.com,
Shuah Khan <skhan@linuxfoundation.org>
Subject: Re: [PATCH v2] selftests/ftrace: Do not trace do_softirq because of PREEMPT_RT
Date: Thu, 10 Feb 2022 15:10:44 +0100 [thread overview]
Message-ID: <YgUc5HxfIdJ0Z5AN@linutronix.de> (raw)
In-Reply-To: <546f147d-1682-fb92-42e5-7247dc19dcf1@canonical.com>
On 2022-02-10 15:05:24 [+0100], Krzysztof Kozlowski wrote:
> On 10/02/2022 14:47, Sebastian Andrzej Siewior wrote:
> > On 2022-02-10 09:33:56 [+0100], Krzysztof Kozlowski wrote:
> >> The PREEMPT_RT patchset does not use soft IRQs thus trying to filter for
> >> do_softirq fails for such kernel:
> >
> > PREEMPT_RT does use soft IRQs.
>
> Correct. It does not use do_softirq() code, but follows different path
> with ksoftirqd.
> Shall I rephrase it towards something like this? Or maybe you have some
> more accurate description?
It would be good to describe what the purpose of the change in terms of
the actual problem and the aimed solution.
> The implementation detail is that do_softirq() is in ifndef.
So let me ask again. We have
FUNC1="schedule"
FUNC2="do_softirq"
What is the purpose of this? Do you need FUNC2 when ksoftirqd is run or
when softirqs are served? Not sure how scheduler_tick fits in all this.
> Best regards,
> Krzysztof
Sebastian
next prev parent reply other threads:[~2022-02-10 14:10 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-10 8:33 [PATCH v2] selftests/ftrace: Do not trace do_softirq because of PREEMPT_RT Krzysztof Kozlowski
2022-02-10 13:47 ` Sebastian Andrzej Siewior
2022-02-10 14:05 ` Krzysztof Kozlowski
2022-02-10 14:10 ` Sebastian Andrzej Siewior [this message]
2022-02-10 14:13 ` Krzysztof Kozlowski
2022-02-10 14:48 ` Sebastian Andrzej Siewior
2022-02-10 15:07 ` Steven Rostedt
2022-02-10 15:05 ` Steven Rostedt
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