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Date:   Wed, 4 Sep 2019 19:47:07 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc:     Joel Fernandes <joel@joelfernandes.org>,
        Qais Yousef <qais.yousef@arm.com>,
        Valentin Schneider <valentin.schneider@arm.com>,
        Radim =?utf-8?B?S3LEjW3DocWZ?= <rkrcmar@redhat.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Ingo Molnar <mingo@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>,
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        Andy Lutomirski <luto@kernel.org>,
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        X86 ML <x86@kernel.org>
Subject: Re: [PATCH 2/2] sched/debug: add sched_update_nr_running tracepoint
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On Wed, Sep 04, 2019 at 08:51:21AM -0700, Alexei Starovoitov wrote:
> Anything in tracing can be deleted.
> Tracing is about debugging and introspection.
> When underlying kernel code changes the introspection points change as well.

Right; except when it breaks widely used tools; like say powertop. Been
there, done that.