Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932952AbbDILWa (ORCPT ); Thu, 9 Apr 2015 07:22:30 -0400 Received: from arroyo.ext.ti.com ([192.94.94.40]:49441 "EHLO arroyo.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755029AbbDILW2 (ORCPT ); Thu, 9 Apr 2015 07:22:28 -0400 Message-ID: <552660C7.4020805@ti.com> Date: Thu, 9 Apr 2015 14:21:43 +0300 From: Tomi Valkeinen User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.6.0 MIME-Version: 1.0 To: Pavel Machek CC: Geert Uytterhoeven , Marek Vasut , kernel list , Dinh Nguyen , Jean-Christophe PLAGNIOL-VILLARD , Grant Likely , Rob Herring , Jingoo Han , Rob Clark , Linux Fbdev development list , "devicetree@vger.kernel.org" , , , , Archit Taneja Subject: Re: simple framebuffer slower by factor of 20, on socfpga (arm) platform References: <20150407121247.GA29497@amd> <20150409110634.GA27407@amd> In-Reply-To: <20150409110634.GA27407@amd> Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="3klL8TUgUQAx1OM5PUfjFXGi7sabpi9XR" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3661 Lines: 108 --3klL8TUgUQAx1OM5PUfjFXGi7sabpi9XR Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable On 09/04/15 14:06, Pavel Machek wrote: > On Tue 2015-04-07 14:19:33, Geert Uytterhoeven wrote: >> Hi Pavel, >> >> On Tue, Apr 7, 2015 at 2:12 PM, Pavel Machek wrote: >>> I have an socfpga board, which uses has simple framebuffer implemente= d >>> in the FPGA. On 3.15, framebuffer is fast: >>> >>> root@wagabuibui:~# time cat /dev/fb0 > /dev/null >>> real 0m 0.00s >>> user 0m 0.00s >>> sys 0m 0.00s >>> >>> on 3.18, this takes 220msec. Similar slowdown exists for >>> writes. Simple framebuffer did not change at all between 3.15 and >>> 3.18; resource flags of the framebuffer are still same (0x200). >>> >>> If I enable caching on 3.18, it speeds up a bit, to 70msec or >>> so... Which means problem is not only in caching. >>> >>> Any ideas? >> >> My first guess was commit 67dc0d4758e5 ("vt_buffer: drop console buff= er >> copying optimisations"), but this was introduced only in v4.0-rc1. >> >> Just in case you encounter another performance regression after upgrad= ing >> to a more modern kernel ;-) >=20 > :-). I did a git bisect, and it pointed to this. And reverting it > indeed fixes the problem in 3.18. Problem is still there in 4.0. Interesting. I can reproduce this also on TI's AM437x board, on 3.14 kernel. Without the patch: # time cat /dev/fb0 > /dev/null real 0m 0.01s user 0m 0.00s sys 0m 0.01s With the patch: # time cat /dev/fb0 > /dev/null real 0m 0.19s user 0m 0.01s sys 0m 0.17s > Archit do you know what is going on there? Should the revert be filled > for 4.0? (Cc'ing Archit's new email) >=20 > Pavel >=20 > commit 981409b25e2a99409b26daa67293ca1cfd5ea0a0 > Author: Archit Taneja > Date: Fri Nov 16 14:46:04 2012 +0530 >=20 > fbdev: arm has __raw I/O accessors, use them in fb.h >=20 > This removes the sparse warnings on arm platforms: >=20 > warning: cast removes address space of expression >=20 > Signed-off-by: Archit Taneja > Signed-off-by: Tomi Valkeinen > Cc: H Hartley Sweeten > Cc: Alexander Shiyan > Cc: Russell King --3klL8TUgUQAx1OM5PUfjFXGi7sabpi9XR Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (GNU/Linux) iQIcBAEBAgAGBQJVJmDIAAoJEPo9qoy8lh7162wP/1X12Y94WLtpvOX6zuG35m4K sKl9lyefh8hBGrSYXGjLrgYVaAAwZjzCTJDGdz83h5DGV2g0Uytie4bArxFR3ipf h9ju/RB9O6TvLmUhybZG8T5PLpunCzAVo7776oCtlTx7UgwfVCa1exqDL4/DeFVA nncxUynFdiPGB+VRTC3hiuoqGQz+I14YM0V0FcTdNDV61W5SQ5Rzh4kJon0B+4hB mH0e2uKbmB2DFBU5tq/Jckq04E8vhAk/IiwRgsdrEmpwDvrKGbNgN03sjwBht1sy UHU/x7+2xeprXdGonQ9G1/6XmN3U/QKcB47NToeoBm98JSiXLUl7o04+TVYE6IHP gOQldjMqrh75E0FfUrwRlAzO/TZcXn32nLhB6RoIWmn+HcBGJdhsgz5aty93JJDO byE150Yh1SQxsIpm8D1KjRyywcsA3GgHh7vQUJyE/AqBNJIqvBo7PibaZy4PUcUg BpYPYAUgKv3lQ2qyCI1orIv3KHI6Za42Zlmx/FHQAiUYKm0I2Rb4s/us5XjJdYI6 W1tqRvatK45SKaIG3mAGbH7cLPN5QVQ2E0i1wgJ8jpqWIq4pRTYIqUYsmSuyPLw+ EYUPRIarkm36fyV7QHV3aQEL5p409HSwzReT6ncMjltuW302jYOju5upI33ctKU/ OhXPY4eOyuUcsShNC9Th =dgVT -----END PGP SIGNATURE----- --3klL8TUgUQAx1OM5PUfjFXGi7sabpi9XR-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/