Message-ID: <1395f577409bb7928dc1d9dc954e1af039253111.camel@linux.intel.com>
Subject: Re: [PATCH v2 0/2] intel_powerclamp: New module parameter
From:   srinivas pandruvada <srinivas.pandruvada@linux.intel.com>
To:     Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Cc:     "Zhang, Rui" <rui.zhang@intel.com>,
        "rafael@kernel.org" <rafael@kernel.org>,
        "Neri, Ricardo" <ricardo.neri@intel.com>,
        "linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "daniel.lezcano@linaro.org" <daniel.lezcano@linaro.org>
Date:   Tue, 07 Feb 2023 05:51:59 -0800
In-Reply-To: <20230207134237.GA13076@ranerica-svr.sc.intel.com>
References: <20230205025902.2899734-1-srinivas.pandruvada@linux.intel.com>
         <a68a6f8c76cb719cd4865bd6aa726306772d4ee3.camel@intel.com>
         <60514763753f572f854f1bbf287c3c16fbbc12c3.camel@linux.intel.com>
         <468eedb9d8a839d22ffd18125d3104f8c014965c.camel@intel.com>
         <f33bc346d8d4ae086ddf59db2670ce9a8f80a250.camel@linux.intel.com>
         <20230207134237.GA13076@ranerica-svr.sc.intel.com>
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On Tue, 2023-02-07 at 05:42 -0800, Ricardo Neri wrote:
> On Mon, Feb 06, 2023 at 02:02:28AM -0800, srinivas pandruvada wrote:
> > On Mon, 2023-02-06 at 08:05 +0000, Zhang, Rui wrote:
> > > On Sun, 2023-02-05 at 18:45 -0800, srinivas pandruvada wrote:
> > > > Hi Rui,
> > > >=20
> > > > On Sun, 2023-02-05 at 15:57 +0000, Zhang, Rui wrote:
> > > > > Hi, Srinivas,
> > > > >=20
> > > > > First of all, the previous build error is gone.
> > > > >=20
> > > > > Second, I found something strange, which may be related with
> > > > > the
> > > > > scheduler asym-packing, so CC Ricardo.
> > > > >=20
> > > > I thought you disable ITMT before idle injection and reenebale
> > > > after
> > > > removal.
> > >=20
> > > No.
> > >=20
> > > I can reproduce this by playing with raw intel_powerclamp sysfs
> > > knobs
> > > and ITMT enabled.
> > >=20
> >=20
> > This issue is happening even if ITMT disabled. If the module mask
> > is
> > composed of P-cores it works or even on servers as expected.
> > Also if you offline all P-cores then select mask among E-cores, it
> > is
> > working. Somehow P-core influences E-cores.
> >=20
> > Since this patch is module mask related, that is functioning
> > correctly.
> > We have to debug this interaction with P and E cores separately.
>=20
> Currently, when doing asym_packing, ECores will only pull tasks from
> a
> PCore only if both SMT siblings are busy. It will only pull from the
> lower-priority sibling. These patches [1] let ECores pull from either
> sibling, if both are busy.
>=20
> I presume that by injecting idle, the scheduler thinks that the CPU
> is
> idle (i.e., idle_cpu() returns true) and it will not do asym_packing
> from
> lower-priority CPUs.
>=20
> However, in your experiment you have 16 threads. If a Pcore is
> overloaded,
> an ECore should be able to help.
This issue happens with or without ITMT and also without any idle
injection active.

Thanks,
Srinivas


>=20
> [1].
> https://lore.kernel.org/lkml/20230207045838.11243-1-ricardo.neri-calderon=
@linux.intel.com/
> =C2=A0