[PATCH rebase] perf/ui/tui: don't force a refresh during progress update

From: Patrick Palka
Date: Fri Oct 25 2013 - 20:26:03 EST

Each call to tui_progress__update() would forcibly refresh the entire
screen. This is somewhat inefficient and causes noticable flickering
during the startup of perf-report, especially on large/slow terminals.

It looks like the force-refresh in tui_progress__update() serves no
purpose other than to clear the screen so that the progress bar of a
previous operation does not subsume that of a subsequent operation.
But we can do just that in a much more efficient manner by clearing only
the region that a previous progress bar may have occupied before
repainting the new progress bar. Then the force-refresh could be
removed with no change in visuals.

This patch disables the slow force-refresh in tui_progress__update() and
instead calls SLsmg_fill_region() on the entire area that the progress
bar may occupy before repainting it. This change makes the startup of
perf-report much faster and appear much "smoother".

It turns out that this was a big bottleneck in the startup speed of
perf-report -- with this patch, perf-report starts up ~2x faster (1.1s
vs 0.55s) on my machines. (These numbers were measured by running
"time perf report" on an 8MB perf.data and pressing 'q' immediately.)

Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Acked-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Patrick Palka <patrick@xxxxxxxxxxxx>
Rebased against
git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git perf/core

And also CC'd two more relevant persons.

tools/perf/ui/tui/progress.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/perf/ui/tui/progress.c b/tools/perf/ui/tui/progress.c
index 3e2d936..c61d14b 100644
--- a/tools/perf/ui/tui/progress.c
+++ b/tools/perf/ui/tui/progress.c
@@ -18,13 +18,14 @@ static void tui_progress__update(struct ui_progress *p)
if (p->total == 0)

- ui__refresh_dimensions(true);
+ ui__refresh_dimensions(false);
y = SLtt_Screen_Rows / 2 - 2;
SLsmg_draw_box(y, 0, 3, SLtt_Screen_Cols);
SLsmg_gotorc(y++, 1);
SLsmg_write_string((char *)p->title);
+ SLsmg_fill_region(y, 1, 1, SLtt_Screen_Cols - 2, ' ');
bar = ((SLtt_Screen_Cols - 2) * p->curr) / p->total;
SLsmg_fill_region(y, 1, 1, bar, ' ');

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