From 7dbc515f5ca4b7867e34c0c4379591cb8b47d64f Mon Sep 17 00:00:00 2001 From: Thomas Zimmermann Date: Wed, 23 Feb 2022 20:38:00 +0100 Subject: 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 Reviewed-by: Javier Martinez Canillas Reviewed-by: Sam Ravnborg Link: https://patchwork.freedesktop.org/patch/msgid/20220223193804.18636-2-tzimmermann@suse.de --- drivers/video/fbdev/core/sysfillrect.c | 16 +++------------- 1 file changed, 3 insertions(+), 13 deletions(-) (limited to 'drivers/video/fbdev/core/sysfillrect.c') 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); -- cgit v1.2.3