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Subject[PATCH 1/2] vgacon: optimize scrolling
Date
Join multiple scr_memcpyw into 1-3 calls (usually 2).
(benchmarked average speedup: 1%)

Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Cc: Antonino Daplas <adaplas@gmail.com>
Cc: linux-fbdev-devel@lists.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


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