Messages in this thread Patch in this message | | | Date | Tue, 20 Nov 2018 11:04:21 +0900 | From | Namhyung Kim <> | Subject | Re: [PATCH 05/12] perf top: Moving lost events warning to helpline |
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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); SLsmg_gotorc(SLtt_Screen_Rows - 1, 0); SLsmg_set_color(0); SLsmg_write_nstring((char *)msg, SLtt_Screen_Cols); SLsmg_refresh(); strncpy(ui_helpline__current, msg, sz)[sz - 1] = '\0'; + pthread_mutex_unlock(&ui__lock); } static int tui_helpline__show(const char *format, va_list ap) -- 2.19.0
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