From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vincent Guittot Subject: Re: [PATCH] arm64: dts: sdm845: Add CPU topology Date: Thu, 6 Jun 2019 09:05:16 +0200 Message-ID: References: <20190114184255.258318-1-mka@chromium.org> <155786856719.14659.2902538189660269078@swboyd.mtv.corp.google.com> <5cdf2dc8.1c69fb81.521c8.9339@mx.google.com> <20190605172048.ahzusevvdxrpnebk@queper01-ThinkPad-T460s> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Return-path: In-Reply-To: <20190605172048.ahzusevvdxrpnebk@queper01-ThinkPad-T460s> Sender: linux-kernel-owner@vger.kernel.org To: Quentin Perret Cc: Stephen Boyd , Amit Kucheria , Andy Gross , Matthias Kaehlcke , David Brown , Rob Herring , Mark Rutland , linux-arm-msm , "open list:ARM/QUALCOMM SUPPORT" , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , LKML , Douglas Anderson , Rajendra Nayak List-Id: devicetree@vger.kernel.org Hi Quentin, On Wed, 5 Jun 2019 at 19:21, Quentin Perret wrote: > > On Friday 17 May 2019 at 14:55:19 (-0700), Stephen Boyd wrote: > > Quoting Amit Kucheria (2019-05-16 04:54:45) > > > (cc'ing Andy's correct email address) > > > > > > On Wed, May 15, 2019 at 2:46 AM Stephen Boyd wrote: > > > > > > > > Quoting Amit Kucheria (2019-05-13 04:54:12) > > > > > On Mon, May 13, 2019 at 4:31 PM Amit Kucheria wrote: > > > > > > > > > > > > On Tue, Jan 15, 2019 at 12:13 AM Matthias Kaehlcke wrote: > > > > > > > > > > > > > > The 8 CPU cores of the SDM845 are organized in two clusters of 4 big > > > > > > > ("gold") and 4 little ("silver") cores. Add a cpu-map node to the DT > > > > > > > that describes this topology. > > > > > > > > > > > > This is partly true. There are two groups of gold and silver cores, > > > > > > but AFAICT they are in a single cluster, not two separate ones. SDM845 > > > > > > is one of the early examples of ARM's Dynamiq architecture. > > > > > > > > > > > > > Signed-off-by: Matthias Kaehlcke > > > > > > > > > > > > I noticed that this patch sneaked through for this merge window but > > > > > > perhaps we can whip up a quick fix for -rc2? > > > > > > > > > > > > > > > > And please find attached a patch to fix this up. Andy, since this > > > > > hasn't landed yet (can we still squash this into the original patch?), > > > > > I couldn't add a Fixes tag. > > > > > > > > > > > > > I had the same concern. Thanks for catching this. I suspect this must > > > > cause some problem for IPA given that it can't discern between the big > > > > and little "power clusters"? > > > > > > Both EAS and IPA, I believe. It influences the scheduler's view of the > > > the topology. > > > > And EAS and IPA are OK with the real topology? I'm just curious if > > changing the topology to reflect reality will be a problem for those > > two. > > FWIW, neither EAS nor IPA depends on this. Not the upstream version of > EAS at least (which is used in recent Android kernels -- 4.19+). > > But doing this is still required for other things in the scheduler (the > so-called 'capacity-awareness' code). So until we have a better > solution, this patch is doing the right thing. I'm not sure to catch what you mean ? Which so-called 'capacity-awareness' code are you speaking about ? and what is the problem ? Regards, Vincent > > I hope that helps. > > Thanks, > Quentin