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[46.139.12.213]) by smtp.gmail.com with ESMTPSA id q25sm1342343wmj.22.2019.09.05.01.13.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 05 Sep 2019 01:13:13 -0700 (PDT) Date: Thu, 5 Sep 2019 10:13:10 +0200 From: Ingo Molnar To: Alexei Starovoitov Cc: Peter Zijlstra , Joel Fernandes , Qais Yousef , Valentin Schneider , Radim =?utf-8?B?S3LEjW3DocWZ?= , LKML , Ingo Molnar , Thomas Gleixner , Borislav Petkov , Dave Hansen , Steven Rostedt , "H. Peter Anvin" , Andy Lutomirski , Jirka =?iso-8859-1?Q?Hladk=FD?= , =?utf-8?B?SmnFmcOtIFZvesOhcg==?= , X86 ML Subject: Re: [PATCH 2/2] sched/debug: add sched_update_nr_running tracepoint Message-ID: <20190905081310.GA46285@gmail.com> References: <20190903154340.860299-3-rkrcmar@redhat.com> <20190904042310.GA159235@google.com> <20190904104332.ogsjtbtuadhsglxh@e107158-lin.cambridge.arm.com> <20190904130628.GE144846@google.com> <20190904154000.GJ240514@google.com> <20190904174707.GV2332@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Alexei Starovoitov wrote: > On Wed, Sep 4, 2019 at 10:47 AM Peter Zijlstra wrote: > > > > 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. > > powertop was a lesson learned, but it's not a relevant example anymore. > There are more widely used tools today. Like bcc tools. > And bpftrace is quickly gaining momentum and large user base. > bcc tools did break already several times and people fixed them. Are these tools using libtraceevents? Thanks, Ingo