diff options
| author | Thomas Zimmermann | 2022-02-23 20:38:00 +0100 |
|---|---|---|
| committer | Thomas Zimmermann | 2022-03-02 20:20:34 +0100 |
| commit | 7dbc515f5ca4b7867e34c0c4379591cb8b47d64f (patch) | |
| tree | 7448c0f6dbb30b0cc90faf88fab968c59db0bc56 /drivers | |
| parent | 81d9d7f8bb8bacd96b2e0e5779e3fba9e86da73f (diff) | |
fbdev: Improve performance of sys_fillrect()
Improve the performance of sys_fillrect() by using word-aligned
32/64-bit mov instructions. While the code tried to implement this,
the compiler failed to create fast instructions. The resulting
binary instructions were even slower than cfb_fillrect(), which
uses the same algorithm, but operates on I/O memory.
A microbenchmark measures the average number of CPU cycles
for sys_fillrect() after a stabilizing period of a few minutes
(i7-4790, FullHD, simpledrm, kernel with debugging). The value
for CFB is given as a reference.
sys_fillrect(), new: 26586 cycles
sys_fillrect(), old: 166603 cycles
cfb_fillrect(): 41012 cycles
In the optimized case, sys_fillrect() is now ~6x faster than before
and ~1.5x faster than the CFB implementation.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20220223193804.18636-2-tzimmermann@suse.de
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/video/fbdev/core/sysfillrect.c | 16 |
1 files changed, 3 insertions, 13 deletions
diff --git a/drivers/video/fbdev/core/sysfillrect.c b/drivers/video/fbdev/core/sysfillrect.c index 33ee3d34f9d2..bcdcaeae6538 100644 --- a/drivers/video/fbdev/core/sysfillrect.c +++ b/drivers/video/fbdev/core/sysfillrect.c @@ -50,19 +50,9 @@ bitfill_aligned(struct fb_info *p, unsigned long *dst, int dst_idx, /* Main chunk */ n /= bits; - while (n >= 8) { - *dst++ = pat; - *dst++ = pat; - *dst++ = pat; - *dst++ = pat; - *dst++ = pat; - *dst++ = pat; - *dst++ = pat; - *dst++ = pat; - n -= 8; - } - while (n--) - *dst++ = pat; + memset_l(dst, pat, n); + dst += n; + /* Trailing bits */ if (last) *dst = comp(pat, *dst, last); |