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Date: Sun, 21 Sep 2008 23:22:17 +0200 From: Marcin Slusarz <marcin.slusarz@...il.com> To: Krzysztof Helt <krzysztof.h1@...zta.fm> Cc: LKML <linux-kernel@...r.kernel.org>, linux-fbdev-devel@...ts.sourceforge.net, Antonino Daplas <adaplas@...il.com> Subject: Re: [Linux-fbdev-devel] [PATCH 1/2] vgacon: optimize scrolling On Sun, Sep 21, 2008 at 08:37:57PM +0200, Krzysztof Helt wrote: > On Sun, 21 Sep 2008 18:00:08 +0200 > Marcin Slusarz <marcin.slusarz@...il.com> wrote: > > > Join multiple scr_memcpyw into 1-3 calls (usually 2). > > (benchmarked average speedup: 1%) > > > > The scr_memcpyw is an inline function so there is no real call here. ... or it's defined to memcpy > However, have you tested the patch with scroll range > 2 * vgacon_scrollback_size? > > It seems that your patch only handles scrolling if it is not bigger than 2 * vgacon_scrollback_size. No. count is always within range <0, c->vc_rows> (look how it's computed just before this loop). Second copy is needed only when end of screen crosses end/beginning of scrollback (it's a circular buffer). > Regards, > Krzysztof > > > Signed-off-by: Marcin Slusarz <marcin.slusarz@...il.com> > > Cc: Antonino Daplas <adaplas@...il.com> > > Cc: linux-fbdev-devel@...ts.sourceforge.net > > --- > > drivers/video/console/vgacon.c | 28 ++++++++++++++++------------ > > 1 files changed, 16 insertions(+), 12 deletions(-) > > > > diff --git a/drivers/video/console/vgacon.c b/drivers/video/console/vgacon.c > > index bd1f57b..de4f66c 100644 > > --- a/drivers/video/console/vgacon.c > > +++ b/drivers/video/console/vgacon.c > > @@ -292,23 +292,27 @@ static int vgacon_scrolldelta(struct vc_data *c, int lines) > > d = (void *) c->vc_origin; > > s = (void *) c->vc_screenbuf; > > > > - while (count--) { > > - scr_memcpyw(d, vgacon_scrollback + soff, c->vc_size_row); > > - d += c->vc_size_row; > > - soff += c->vc_size_row; > > - > > - if (soff >= vgacon_scrollback_size) > > - soff = 0; > > + if (count) { > > + int copysize; > > + count *= c->vc_size_row; > > + /* how much memory to end of buffer left? */ > > + copysize = min(count, vgacon_scrollback_size - soff); > > + scr_memcpyw(d, vgacon_scrollback + soff, copysize); > > + d += copysize; > > + count -= copysize; > > + > > + if (count) { > > + copysize = min(count, vgacon_scrollback_size); > > + scr_memcpyw(d, vgacon_scrollback, copysize); > > + d += copysize; > > + } > > } > > > > if (diff == c->vc_rows) { > > vgacon_cursor(c, CM_MOVE); > > } else { > > - while (diff--) { > > - scr_memcpyw(d, s, c->vc_size_row); > > - d += c->vc_size_row; > > - s += c->vc_size_row; > > - } > > + if (diff) > > + scr_memcpyw(d, s, diff * c->vc_size_row); > > } > > > > return 1; > > -- > > 1.5.6.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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