From: Quentin Perret <quentin.perret@arm.com>
To: Stephen Boyd <swboyd@chromium.org>
Cc: Amit Kucheria <amit.kucheria@linaro.org>,
Andy Gross <agross@kernel.org>,
Matthias Kaehlcke <mka@chromium.org>,
David Brown <david.brown@linaro.org>,
Rob Herring <robh+dt@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
linux-arm-msm <linux-arm-msm@vger.kernel.org>,
"open list:ARM/QUALCOMM SUPPORT" <linux-soc@vger.kernel.org>,
"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>,
Douglas Anderson <dianders@chromium.org>,
Rajendra Nayak <rnayak@codeaurora.org>
Subject: Re: [PATCH] arm64: dts: sdm845: Add CPU topology
Date: Wed, 5 Jun 2019 18:20:52 +0100 [thread overview]
Message-ID: <20190605172048.ahzusevvdxrpnebk@queper01-ThinkPad-T460s> (raw)
In-Reply-To: <5cdf2dc8.1c69fb81.521c8.9339@mx.google.com>
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 <swboyd@chromium.org> wrote:
> > >
> > > Quoting Amit Kucheria (2019-05-13 04:54:12)
> > > > On Mon, May 13, 2019 at 4:31 PM Amit Kucheria <amit.kucheria@linaro.org> wrote:
> > > > >
> > > > > On Tue, Jan 15, 2019 at 12:13 AM Matthias Kaehlcke <mka@chromium.org> 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 <mka@chromium.org>
> > > > >
> > > > > 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 hope that helps.
Thanks,
Quentin
next prev parent reply other threads:[~2019-06-05 17:21 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-14 18:42 [PATCH] arm64: dts: sdm845: Add CPU topology Matthias Kaehlcke
2019-01-18 2:50 ` Doug Anderson
2019-05-13 11:01 ` Amit Kucheria
2019-05-13 11:54 ` Amit Kucheria
2019-05-14 21:16 ` Stephen Boyd
2019-05-16 11:54 ` Amit Kucheria
2019-05-17 21:55 ` Stephen Boyd
2019-06-05 17:20 ` Quentin Perret [this message]
2019-06-06 7:05 ` Vincent Guittot
2019-06-06 7:49 ` Quentin Perret
2019-06-06 8:20 ` Vincent Guittot
2019-06-06 8:29 ` Quentin Perret
2019-06-06 8:34 ` Dietmar Eggemann
2019-06-06 8:44 ` Vincent Guittot
2019-06-06 10:50 ` Morten Rasmussen
2019-05-22 4:03 ` Bjorn Andersson
2019-05-16 13:22 ` Sudeep Holla
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