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

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Date:	Mon, 28 Oct 2013 14:52:33 +0900
From:	Namhyung Kim <namhyung@...nel.org>
To:	Patrick Palka <patrick@...cs.ath.cx>
Cc:	linux-kernel@...r.kernel.org,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>,
	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	Ingo Molnar <mingo@...nel.org>
Subject: Re: [PATCH rebase] perf/ui/tui: don't force a refresh during progress update

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 perf.data and pressing 'q' immediately.)

Acked-by: Namhyung Kim <namhyung@...nel.org>

Thanks,
Namhyung
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