dri-devel.lists.freedesktop.org archive mirror
 help / color / mirror / Atom feed
From: Thomas Zimmermann <tzimmermann@suse.de>
To: daniel@ffwll.ch, deller@gmx.de, javierm@redhat.com,
	geert@linux-m68k.org, sam@ravnborg.org, kraxel@redhat.com
Cc: linux-fbdev@vger.kernel.org,
	Thomas Zimmermann <tzimmermann@suse.de>,
	dri-devel@lists.freedesktop.org
Subject: [PATCH v2 1/5] fbdev: Improve performance of sys_fillrect()
Date: Mon, 21 Feb 2022 20:54:06 +0100	[thread overview]
Message-ID: <20220221195410.9172-2-tzimmermann@suse.de> (raw)
In-Reply-To: <20220221195410.9172-1-tzimmermann@suse.de>

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>
---
 drivers/video/fbdev/core/sysfillrect.c | 16 +++-------------
 1 file 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);
-- 
2.35.1


  reply	other threads:[~2022-02-21 19:54 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-21 19:54 [PATCH v2 0/5] fbdev: Improve performance of fbdev console Thomas Zimmermann
2022-02-21 19:54 ` Thomas Zimmermann [this message]
2022-02-21 19:54 ` [PATCH v2 2/5] fbdev: Improve performance of sys_imageblit() Thomas Zimmermann
2022-02-21 19:54 ` [PATCH v2 3/5] fbdev: Remove trailing whitespaces from cfbimgblt.c Thomas Zimmermann
2022-02-21 19:54 ` [PATCH v2 4/5] fbdev: Improve performance of cfb_imageblit() Thomas Zimmermann
2022-02-22 13:01   ` Pekka Paalanen
2022-02-22 18:48     ` Thomas Zimmermann
2022-02-21 19:54 ` [PATCH v2 5/5] drm: Add TODO item for optimizing format helpers Thomas Zimmermann

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20220221195410.9172-2-tzimmermann@suse.de \
    --to=tzimmermann@suse.de \
    --cc=daniel@ffwll.ch \
    --cc=deller@gmx.de \
    --cc=dri-devel@lists.freedesktop.org \
    --cc=geert@linux-m68k.org \
    --cc=javierm@redhat.com \
    --cc=kraxel@redhat.com \
    --cc=linux-fbdev@vger.kernel.org \
    --cc=sam@ravnborg.org \
    --subject='Re: [PATCH v2 1/5] fbdev: Improve performance of sys_fillrect()' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).