From owner-freebsd-arm@FreeBSD.ORG Fri Mar 7 14:32:40 2014 Return-Path: Delivered-To: freebsd-arm@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 52EC24B1 for ; Fri, 7 Mar 2014 14:32:40 +0000 (UTC) Received: from mail-pa0-f54.google.com (mail-pa0-f54.google.com [209.85.220.54]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id 2623577F for ; Fri, 7 Mar 2014 14:32:39 +0000 (UTC) Received: by mail-pa0-f54.google.com with SMTP id lf10so4270566pab.27 for ; Fri, 07 Mar 2014 06:32:39 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:sender:content-type:mime-version:subject:from :in-reply-to:date:cc:content-transfer-encoding:message-id:references :to; bh=pzW5RET2Kj0AtxZZ6K0nwVr+w20ru+zQ2jomWCvyVJg=; b=Rg1j1Mw1NCshqPXSi/PVi04RqGQGW4OjKmepQeNev8er72r5BsaYVw1LmV0dMcZLRK 7Vp1r9ghPLr+SKUgRrqQJEGslafsv75o6hBGUA0PdabvNilf/jtggXoxKZ8Gu52ZRGqR 5g7QOiyjnzHQXDXWMe5x6ynb+UAsr+z/uBCJ1nS+++Ji3lGTMKDGV2B92rqRc2bVlt41 Tc01gfKgCJePuMglY4k+3sromOn/QWrbFmqL5G5QAUEIQaKIZ+u6XLfd66bdeVOF5XKo InRith6LYXguybPTZVX4Zjchez7WyUiZLlYdgcSiP8hRyTKjmNiIFjFp47YvMKzp9wlk 6WeA== X-Gm-Message-State: ALoCoQnLOCHiaeATFsOaiZQ6mIYuraCwuCd9WL7eBQeY39OjPAPzLxIqEKv23Of1WhAELO4CpN4V X-Received: by 10.66.66.66 with SMTP id d2mr22389528pat.80.1394202759338; Fri, 07 Mar 2014 06:32:39 -0800 (PST) Received: from netflix-mac.bsdimp.com (50-78-194-198-static.hfc.comcastbusiness.net. [50.78.194.198]) by mx.google.com with ESMTPSA id g6sm8585105pat.2.2014.03.07.06.32.38 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Fri, 07 Mar 2014 06:32:38 -0800 (PST) Sender: Warner Losh Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 7.2 \(1874\)) Subject: Re: ULE on ARM From: Warner Losh In-Reply-To: <1394202304.1149.373.camel@revolution.hippie.lan> Date: Fri, 7 Mar 2014 07:32:36 -0700 Content-Transfer-Encoding: 7bit Message-Id: <3BE23B6A-900C-4104-A398-30D5B2A282DB@bsdimp.com> References: <20140307141406.GA79223@machdep.com> <1394202304.1149.373.camel@revolution.hippie.lan> To: Ian Lepore X-Mailer: Apple Mail (2.1874) Cc: freebsd-arm , Ruslan Bukin X-BeenThere: freebsd-arm@freebsd.org X-Mailman-Version: 2.1.17 Precedence: list List-Id: "Porting FreeBSD to ARM processors." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 07 Mar 2014 14:32:40 -0000 On Mar 7, 2014, at 7:25 AM, Ian Lepore wrote: > On Fri, 2014-03-07 at 18:14 +0400, Ruslan Bukin wrote: >> I discovered just a couple of ARM kernel configs >> uses SCHED_ULE, but all other uses SCHED_4BSD >> >> any disadvantages to use ULE scheduler on ARM? >> or it is just because of historical reasons? >> >> I enabled ULE on Freescale Vybrid and running >> it for a long time just fine. >> >> according to my subjective impressions ULE >> works better on ARM in sound applications >> >> -Ruslan > > The widespread advice from a few years ago was that ULE was better for > SMP and 4BSD was better for UP. I don't know whether that's still true > (or whether it was ever true). I do know that there are fewer responses > on mailing lists of "try switching the scheduler to 4BSD" as a way of > fixing problems these days. I switched imx6 to ULE when adding SMP > support for it. It all depends on the workload. 4BSD is better for some SMP workloads, while ULE is better for others. But as a general rule, Ian is right: 4BSD tends to be better at UP interactive workloads, while ULE tends to be better at MP work loads that have a larger compute element to them (complex transactions). Warner