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

From: Namhyung Kim
Date: Mon Oct 28 2013 - 01:52:39 EST

Hi Patrick,

On Fri, 25 Oct 2013 20:25:49 -0400, Patrick Palka wrote:
> 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 and pressing 'q' immediately.)

Acked-by: Namhyung Kim <namhyung@xxxxxxxxxx>

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