From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f67.google.com (mail-wm0-f67.google.com [74.125.82.67]) by mail.openembedded.org (Postfix) with ESMTP id 3F5E76FEE0 for ; Mon, 11 Jan 2016 23:18:18 +0000 (UTC) Received: by mail-wm0-f67.google.com with SMTP id l65so28451021wmf.3 for ; Mon, 11 Jan 2016 15:18:19 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=IOlLxFl3aC1cS213cf2SqujtYRvRTS+/Q7xHM4v+aBE=; b=vpKT6Katu5Y/HtTlXIY2JJRdBlgIghmSud+H4e/OPOBfJdJkB+4uBLX8rRObtR96n+ 1Wj1UxojpER8JHtKHwiquCoDbOzVXFU4NT+MmJ64kjdeQXxj4YJswXXpKSg07KB7tGt/ OIbzc6b9JpcEgFaEZbYjaJDzpNC6O8NQQfPbehFlJKArTItdAKloD4gIAHz2MI8GRjbk EvsyS57hDLkZn7+YS5yvrTSVc1jGjr126DIoUpFNJw927EI5b2qcGEZ0ycWjN14fdk/a mfNxQqkZT6jNU1ViM71NaATkAY0M6jNYzYW38j5yhcygF7sZKEbCTdxmuPlK9yDtLNIr uUSw== MIME-Version: 1.0 X-Received: by 10.194.203.99 with SMTP id kp3mr137609482wjc.3.1452554298813; Mon, 11 Jan 2016 15:18:18 -0800 (PST) Received: by 10.194.209.131 with HTTP; Mon, 11 Jan 2016 15:18:18 -0800 (PST) In-Reply-To: <1452553655.7598.206.camel@linuxfoundation.org> References: <1452205752-6353-1-git-send-email-armccurdy@gmail.com> <1452205752-6353-4-git-send-email-armccurdy@gmail.com> <1452210004.2002.129.camel@pbcl.net> <4E2CA517-1339-416B-832B-AB2EFF04CEE6@gmail.com> <1452553655.7598.206.camel@linuxfoundation.org> Date: Mon, 11 Jan 2016 15:18:18 -0800 Message-ID: From: Andre McCurdy To: Richard Purdie Cc: OE Core mailing list Subject: Re: [PATCH v2 3/4] libav.inc: duplicate armv7a over-rides for armv7ve X-BeenThere: openembedded-core@lists.openembedded.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Patches and discussions about the oe-core layer List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 11 Jan 2016 23:18:19 -0000 Content-Type: text/plain; charset=UTF-8 On Mon, Jan 11, 2016 at 3:07 PM, Richard Purdie wrote: > On Mon, 2016-01-11 at 14:58 -0800, Khem Raj wrote: >> > On Jan 7, 2016, at 3:40 PM, Phil Blundell wrote: >> > >> > On Thu, 2016-01-07 at 14:29 -0800, Andre McCurdy wrote: >> > > FULL_OPTIMIZATION_armv7a = "-fexpensive-optimizations -fomit >> > > -frame-pointer -O4 -ffast-math" >> > > +FULL_OPTIMIZATION_armv7ve = "-fexpensive-optimizations -fomit >> > > -frame-pointer -O4 -ffast-math" >> >> O4 ? may be just replace this whole thing with -Ofast now a days >> -fexpensive-optimizations is enabled at -O2,-O3 anyway same for fomit >> -frame-pointer and -Ofast turns on >> feast-match on top of -O3 >> >> > I wonder if this would be better as just FULL_OPTIMIZATION_arm. >> > That >> > said, the OPTIMIZATION variables are primarily distro knobs and >> > it's not >> > entirely clear that individual packages ought to be overriding them >> > at >> > all. >> > >> > Does anybody know whether there is any actual science behind the >> > use of >> > those flags on armv7a specifically? >> >> it came into ffmpeg circa 2008 and proliferated into related >> components primarily to support vectorization and neon >> which was quite nascent for ARM architecture in those days in gcc. >> Today if you were to configure libav with default options >> then it uses mainly -fomit-frame-pointer-O3 -fno-math-errno -fno >> -signed-zeros -fno-tree-vectorize >> >> which is primarily -Ofast -fno-tree-vectorize > > I have to admit that my personal instinct on these is simply to remove > them. I doubt they're buying much now and if people really want to tune > specific recipes by hand they still can do so from their local/distro > config. It's the other armv7a over-ride which probably needs more careful consideration, ie: EXTRA_FFCONF_armv7a = "--cpu=cortex-a8" Khem, did you look into that? What happens to libav if we don't configure for a suitable CPU? > Cheers, > > Richard > > -- > _______________________________________________ > Openembedded-core mailing list > Openembedded-core@lists.openembedded.org > http://lists.openembedded.org/mailman/listinfo/openembedded-core