Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934399AbeAKO0m (ORCPT + 1 other); Thu, 11 Jan 2018 09:26:42 -0500 Received: from mx1.redhat.com ([209.132.183.28]:58984 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933378AbeAKO0k (ORCPT ); Thu, 11 Jan 2018 09:26:40 -0500 Date: Thu, 11 Jan 2018 15:26:26 +0100 From: Jiri Olsa To: kan.liang@intel.com Cc: acme@kernel.org, peterz@infradead.org, mingo@redhat.com, linux-kernel@vger.kernel.org, wangnan0@huawei.com, jolsa@kernel.org, namhyung@kernel.org, ak@linux.intel.com, yao.jin@linux.intel.com Subject: Re: [PATCH V3 10/12] perf top: add overwrite fall back Message-ID: <20180111142626.GH16655@krava> References: <1513879734-237492-1-git-send-email-kan.liang@intel.com> <1513879734-237492-11-git-send-email-kan.liang@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1513879734-237492-11-git-send-email-kan.liang@intel.com> User-Agent: Mutt/1.9.1 (2017-09-22) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Thu, 11 Jan 2018 14:26:40 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: On Thu, Dec 21, 2017 at 10:08:52AM -0800, kan.liang@intel.com wrote: > From: Kan Liang > > Switch to non-overwrite mode if kernel doesnot support overwrite > ringbuffer. > > It's only effect when overwrite mode is supported. > No change to current behavior. > > Signed-off-by: Kan Liang > --- > tools/perf/builtin-top.c | 36 ++++++++++++++++++++++++++++++++++++ > 1 file changed, 36 insertions(+) > > diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c > index 4b85e7b..8d19ef7 100644 > --- a/tools/perf/builtin-top.c > +++ b/tools/perf/builtin-top.c > @@ -931,6 +931,27 @@ static int perf_top_overwrite_check(struct perf_top *top) > return 0; > } > > +static int perf_top_overwrite_fallback(struct perf_top *top, > + struct perf_evsel *evsel) > +{ > + struct record_opts *opts = &top->record_opts; > + struct perf_evlist *evlist = top->evlist; > + struct perf_evsel *counter; > + > + if (!opts->overwrite) > + return 0; > + > + /* only fall back when first event fails */ > + if (evsel != perf_evlist__first(evlist)) > + return 0; > + > + evlist__for_each_entry(evlist, counter) > + counter->attr.write_backward = false; > + opts->overwrite = false; > + ui__warning("fall back to non-overwrite mode\n"); > + return 1; > +} we already do that for evsel in perf_evsel__open.. could we make this fallback on one place only? checking the code, why don't we follow the perf_missing_features.write_backward like we do for other features in the perf_evsel__open and set write_backward accordingly, like in attached patch. jirka --- diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c index dbd80268de54..89253f4ff9ee 100644 --- a/tools/perf/util/evsel.c +++ b/tools/perf/util/evsel.c @@ -1683,9 +1683,6 @@ int perf_evsel__open(struct perf_evsel *evsel, struct cpu_map *cpus, int pid = -1, err; enum { NO_CHANGE, SET_TO_MAX, INCREASED_MAX } set_rlimit = NO_CHANGE; - if (perf_missing_features.write_backward && evsel->attr.write_backward) - return -EINVAL; - if (cpus == NULL) { static struct cpu_map *empty_cpu_map; @@ -1725,6 +1722,8 @@ int perf_evsel__open(struct perf_evsel *evsel, struct cpu_map *cpus, } fallback_missing_features: + if (perf_missing_features.write_backward) + evsel->attr.write_backward = false; if (perf_missing_features.clockid_wrong) evsel->attr.clockid = CLOCK_MONOTONIC; /* should always work */ if (perf_missing_features.clockid) {