Messages in this thread | | | Date | Tue, 20 Nov 2018 12:41:44 +0100 | From | Jiri Olsa <> | Subject | Re: [PATCH 05/12] perf top: Moving lost events warning to helpline |
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On Tue, Nov 20, 2018 at 11:04:21AM +0900, Namhyung Kim wrote: > On Mon, Nov 19, 2018 at 01:20:09PM +0100, Jiri Olsa wrote: > > We can't display the UI box saying that we are slow in reader > > thread. That will make perf top even slower and user even more > > angry ;-) > > > > Moving the UI box message out of the reader thread into UI thread > > and changing it into helpline, so there's no 'press any key' > > necessary. > > > > Link: http://lkml.kernel.org/n/tip-0rpmmt3omlait889ewp1cl61@git.kernel.org > > Signed-off-by: Jiri Olsa <jolsa@kernel.org> > > --- > > tools/perf/builtin-top.c | 16 +++++----------- > > 1 file changed, 5 insertions(+), 11 deletions(-) > > > > diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c > > index 047e99de09f3..1d77aa7650da 100644 > > --- a/tools/perf/builtin-top.c > > +++ b/tools/perf/builtin-top.c > > @@ -553,8 +553,6 @@ static void perf_top__sort_new_samples(void *arg) > > struct perf_evsel *evsel = t->sym_evsel; > > struct hists *hists; > > > > - perf_top__reset_sample_counters(t); > > - > > if (t->evlist->selected != NULL) > > t->sym_evsel = t->evlist->selected; > > > > @@ -571,6 +569,11 @@ static void perf_top__sort_new_samples(void *arg) > > > > hists__collapse_resort(hists, NULL); > > perf_evsel__output_resort(evsel, NULL); > > + > > + if (t->lost) > > + ui_helpline__fpush("Too slow to read ring buffer (change period (-c/-F) or limit CPUs (-C)\n"); > > In general, ui_helpline__[f]push() requires corresponding __pop() > which handles timeout logic (or something can dismiss the message). > The ui_helpline__show() is to show the message and overwrite the old > one. > > But we don't use it strictly and I think just pr_err() or pr_warning() > is ok here (which call ui_helpline__show() internally). > > Anyway, I found that tui_helpline__push() should use ui__lock. > Otherwise it could race with display thread and break rendering. > A bug from the beginning but no one reported... :) > > Thanks, > Namhyung > > > From a5c3a0c88b9d13fedc65b61a45d99fc3abef0089 Mon Sep 17 00:00:00 2001 > From: Namhyung Kim <namhyung@kernel.org> > Date: Tue, 20 Nov 2018 10:56:03 +0900 > Subject: [PATCH] perf ui/tui: Fix possible UI rendering breakage > > The tui_helpline__push() should acquire/release the ui__lock when it > deals with screen setting. Otherwise it could race with display thread > and screen rendering would not be handled properly. > > Fixes: e6e904687949 ("perf ui: Introduce struct ui_helpline") > Signed-off-by: Namhyung Kim <namhyung@kernel.org> > --- > tools/perf/ui/tui/helpline.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/tools/perf/ui/tui/helpline.c b/tools/perf/ui/tui/helpline.c > index 4ca799aadb4e..ff38b997f457 100644 > --- a/tools/perf/ui/tui/helpline.c > +++ b/tools/perf/ui/tui/helpline.c > @@ -20,11 +20,13 @@ static void tui_helpline__push(const char *msg) > { > const size_t sz = sizeof(ui_helpline__current); > > + pthread_mutex_lock(&ui__lock);
hum, I haven't tested but in ui_browser__show there's ui_helpline__push call under locked ui__lock
jirka
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