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Fri, 17 Apr 2020 14:37:06 -0700 (PDT) From: Arnaldo Carvalho de Melo X-Google-Original-From: Arnaldo Carvalho de Melo Received: by quaco.ghostprotocols.net (Postfix, from userid 1000) id 50557409A3; Fri, 17 Apr 2020 18:37:04 -0300 (-03) Date: Fri, 17 Apr 2020 18:37:04 -0300 To: Andi Kleen , Adrian Hunter Cc: Arnaldo Carvalho de Melo , Jiri Olsa , linux-kernel@vger.kernel.org, Namhyung Kim , linux-perf-users@vger.kernel.org Subject: Re: [PATCH 11/16] perf intel-pt: Add support for synthesizing callchains for regular events Message-ID: <20200417213704.GB21512@kernel.org> References: <20200401101613.6201-1-adrian.hunter@intel.com> <20200401101613.6201-12-adrian.hunter@intel.com> <20200416151443.GA2650@kernel.org> <5b8f28f5-968f-bfff-68af-ed0350a90765@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5b8f28f5-968f-bfff-68af-ed0350a90765@intel.com> X-Url: http://acmel.wordpress.com Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Em Fri, Apr 17, 2020 at 04:50:00PM +0300, Adrian Hunter escreveu: > On 16/04/20 6:14 pm, Arnaldo Carvalho de Melo wrote: > > Em Wed, Apr 01, 2020 at 01:16:08PM +0300, Adrian Hunter escreveu: > >> Currently, callchains can be synthesized only for synthesized events. > >> Support also synthesizing callchains for regular events. > > > > This is super cool, I wonder if we shouldn't do it automatically or just > > adding a new type of callchains, i.e.: > > > > perf record --call-graph pt uname > > > > Should take care of all the details, i.e. do the extra steps below > > behind the scenes. > > > > Possibly even find out that the workload specified was built with > > -fomit-frame-pointers, that the hardware has Intel PT and do all behind > > the scenes for: > > > > perf record -g uname > > > > Alternatively we could take some less seemingly far fetched approach and > > make this configurable via: > > > > perf config call-graph.record-mode=pt > > > > What do you think? > > Adding a --call-graph option sounds reasonable, and config to define default > callgraph options. But this was done at Andi Kleen's request, so he may > want to comment. Andi? My concern is that if this is the optimal solution for a good subset of the machines out there, then we need to make it easy to use, even transparent, if possible and safe to take that path. - Arnaldo