From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: <ffmpeg-devel-bounces@ffmpeg.org> Received: from ffbox0-bg.ffmpeg.org (ffbox0-bg.ffmpeg.org [79.124.17.100]) by master.gitmailbox.com (Postfix) with ESMTPS id 6729D4CA89 for <ffmpegdev@gitmailbox.com>; Tue, 27 May 2025 08:52:03 +0000 (UTC) Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.ffmpeg.org (Postfix) with ESMTP id 470D568D546; Tue, 27 May 2025 11:52:00 +0300 (EEST) Received: from haasn.dev (haasn.dev [78.46.187.166]) by ffbox0-bg.ffmpeg.org (Postfix) with ESMTP id EDF7068D470 for <ffmpeg-devel@ffmpeg.org>; Tue, 27 May 2025 11:51:53 +0300 (EEST) Received: from haasn.dev (unknown [10.30.1.1]) by haasn.dev (Postfix) with UTF8SMTP id B17F34076C; Tue, 27 May 2025 10:51:53 +0200 (CEST) Date: Tue, 27 May 2025 10:51:53 +0200 Message-ID: <20250527105153.GF38697@haasn.xyz> From: Niklas Haas <ffmpeg@haasn.xyz> To: Kieran Kunhya via ffmpeg-devel <ffmpeg-devel@ffmpeg.org>, FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org> In-Reply-To: <CABGuwEmPupY2QBxX+qw4sW-S+efMR8OuLLMRFEbWczJQzZANZg@mail.gmail.com> References: <20250527081242.22892-1-ffmpeg@haasn.xyz> <CABGuwEmPupY2QBxX+qw4sW-S+efMR8OuLLMRFEbWczJQzZANZg@mail.gmail.com> MIME-Version: 1.0 Content-Disposition: inline Subject: Re: [FFmpeg-devel] (no subject) X-BeenThere: ffmpeg-devel@ffmpeg.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: FFmpeg development discussions and patches <ffmpeg-devel.ffmpeg.org> List-Unsubscribe: <https://ffmpeg.org/mailman/options/ffmpeg-devel>, <mailto:ffmpeg-devel-request@ffmpeg.org?subject=unsubscribe> List-Archive: <https://ffmpeg.org/pipermail/ffmpeg-devel> List-Post: <mailto:ffmpeg-devel@ffmpeg.org> List-Help: <mailto:ffmpeg-devel-request@ffmpeg.org?subject=help> List-Subscribe: <https://ffmpeg.org/mailman/listinfo/ffmpeg-devel>, <mailto:ffmpeg-devel-request@ffmpeg.org?subject=subscribe> Reply-To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org> Cc: Kieran Kunhya <kieran618@googlemail.com> Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" <ffmpeg-devel-bounces@ffmpeg.org> Archived-At: <https://master.gitmailbox.com/ffmpegdev/20250527105153.GF38697@haasn.xyz/> List-Archive: <https://master.gitmailbox.com/ffmpegdev/> List-Post: <mailto:ffmpegdev@gitmailbox.com> On Tue, 27 May 2025 16:29:20 +0800 Kieran Kunhya via ffmpeg-devel <ffmpeg-devel@ffmpeg.org> wrote: > > > > - adding vzeroupper: ~12% > > > > This seems quite suspicious. > Can you explain what you are doing here? I added a vzeroupper call whenever the code transitions from AVX to SSE. For example: Conversion pass for yuv444p -> rgba: [ u8 XXXX -> +++X] SWS_OP_READ : 3 elem(s) planar >> 0 [ u8 ...X -> +++X] SWS_OP_CONVERT : u8 -> f32 [f32 ...X -> ...X] SWS_OP_LINEAR : matrix3+off3 [[85/73 0 1.596027 0 -222.921566] [85/73 -0.391762 -0.812968 0 135.575295] [85/73 2.017232 0 0 -276.835851] [0 0 0 1 0]] [f32 ...X -> ...X] SWS_OP_DITHER : 16x16 matrix [f32 ...X -> ...X] SWS_OP_MAX : {0 0 0 0} <= x [f32 ...X -> ...X] SWS_OP_MIN : x <= {255 255 255 255} [f32 ...X -> +++X] SWS_OP_CONVERT : f32 -> u8 ^-------- vzeroupper call added here [ u8 ...X -> ++++] SWS_OP_CLEAR : {_ _ _ 255} [ u8 .... -> ++++] SWS_OP_WRITE : 4 elem(s) packed >> 0 yuv444p 1920x1080 -> rgba 1920x1080, flags=0x100000 dither=1, SSIM {Y=1.000000 U=0.999999 V=0.999997 A=1.000000} time=911 us, ref=4257 us, speedup=4.669x faster With the vzeroupper commented out: yuv444p 1920x1080 -> rgba 1920x1080, flags=0x100000 dither=1, SSIM {Y=1.000000 U=0.999999 V=0.999997 A=1.000000} time=1361 us, ref=4265 us, speedup=3.133x faster In most other cases, it does not matter, but in some cases like here, not having the vzeroupper call introduces false dependencies. Another example is grayf32 -> yuv444p, which goes from 268 us to 296 us if I remove the vzeroupper calls. In general, anything involving switching between 32-bit floats (512 bits per block) and 8-bit integers (128 bits per block) sees an effect. > > Kieran > > > > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel > > To unsubscribe, visit link above, or email > ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe". _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".