Re: [PATCH v3 3/4] powercap: Add AMD Fam17h RAPL support

From: Victor Ding <victording@google.com>
To: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Cc: Zhang Rui <rui.zhang@intel.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Daniel Lezcano <daniel.lezcano@linaro.org>,
	Kim Phillips <kim.phillips@amd.com>,
	linux-pm@vger.kernel.org, Borislav Petkov <bp@alien8.de>,
	"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
	Joerg Roedel <jroedel@suse.de>,
	Kan Liang <kan.liang@linux.intel.com>,
	Pawan Gupta <pawan.kumar.gupta@linux.intel.com>,
	"Peter Zijlstra (Intel)" <peterz@infradead.org>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Sean Christopherson <sean.j.christopherson@intel.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Tony Luck <tony.luck@intel.com>,
	Vineela Tummalapalli <vineela.tummalapalli@intel.com>,
	x86@kernel.org
Subject: Re: [PATCH v3 3/4] powercap: Add AMD Fam17h RAPL support
Date: Wed, 4 Nov 2020 12:43:30 +1100	[thread overview]
Message-ID: <CANqTbdaePLt-kYdihFzZ1Bjns=OfKwWxiYp5-JwfONm7Ujqi+Q@mail.gmail.com> (raw)
In-Reply-To: <f7562a2492aa83afa8a3a511428ed1959b8e8c72.camel@linux.intel.com>

On Wed, Nov 4, 2020 at 4:09 AM Srinivas Pandruvada
<srinivas.pandruvada@linux.intel.com> wrote:
>
> On Tue, 2020-11-03 at 17:10 +1100, Victor Ding wrote:
> > On Mon, Nov 2, 2020 at 12:39 PM Zhang Rui <rui.zhang@intel.com>
> > wrote:
> > > On Tue, 2020-10-27 at 07:23 +0000, Victor Ding wrote:
> > > > This patch enables AMD Fam17h RAPL support for the power capping
> > > > framework. The support is as per AMD Fam17h Model31h (Zen2) and
> > > > model 00-ffh (Zen1) PPR.
> > > >
> > > > Tested by comparing the results of following two sysfs entries
> > > > and
> > > > the
> > > > values directly read from corresponding MSRs via
> > > > /dev/cpu/[x]/msr:
> > > >   /sys/class/powercap/intel-rapl/intel-rapl:0/energy_uj
> > > >   /sys/class/powercap/intel-rapl/intel-rapl:0/intel-
> > > > rapl:0:0/energy_uj
>
> Is this for just energy reporting? No capping of power?
Correct, the hardware does not support capping of power.
>
> Thanks,
> Srinivas
>
>
> > > >
> > > > Signed-off-by: Victor Ding <victording@google.com>
> > > > Acked-by: Kim Phillips <kim.phillips@amd.com>
> > > >
> > > >
> > > > ---
> > > >
> > > > Changes in v3:
> > > > By Victor Ding <victording@google.com>
> > > >  - Rebased to the latest code.
> > > >  - Created a new rapl_defaults for AMD CPUs.
> > > >  - Removed redundant setting to zeros.
> > > >  - Stopped using the fake power limit domain 1.
> > > >
> > > > Changes in v2:
> > > > By Kim Phillips <kim.phillips@amd.com>:
> > > >  - Added Kim's Acked-by.
> > > >  - Added Daniel Lezcano to Cc.
> > > >  - (No code change).
> > > >
> > > >  arch/x86/include/asm/msr-index.h     |  1 +
> > > >  drivers/powercap/intel_rapl_common.c |  6 ++++++
> > > >  drivers/powercap/intel_rapl_msr.c    | 20 +++++++++++++++++++-
> > > >  3 files changed, 26 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/arch/x86/include/asm/msr-index.h
> > > > b/arch/x86/include/asm/msr-index.h
> > > > index 21917e134ad4..c36a083c8ec0 100644
> > > > --- a/arch/x86/include/asm/msr-index.h
> > > > +++ b/arch/x86/include/asm/msr-index.h
> > > > @@ -327,6 +327,7 @@
> > > >  #define MSR_PP1_POLICY                       0x00000642
> > > >
> > > >  #define MSR_AMD_RAPL_POWER_UNIT              0xc0010299
> > > > +#define MSR_AMD_CORE_ENERGY_STATUS           0xc001029a
> > > >  #define MSR_AMD_PKG_ENERGY_STATUS    0xc001029b
> > > >
> > > >  /* Config TDP MSRs */
> > > > diff --git a/drivers/powercap/intel_rapl_common.c
> > > > b/drivers/powercap/intel_rapl_common.c
> > > > index 0b2830efc574..bedd780bed12 100644
> > > > --- a/drivers/powercap/intel_rapl_common.c
> > > > +++ b/drivers/powercap/intel_rapl_common.c
> > > > @@ -1011,6 +1011,10 @@ static const struct rapl_defaults
> > > > rapl_defaults_cht = {
> > > >       .compute_time_window = rapl_compute_time_window_atom,
> > > >  };
> > > >
> > > > +static const struct rapl_defaults rapl_defaults_amd = {
> > > > +     .check_unit = rapl_check_unit_core,
> > > > +};
> > > > +
> > >
> > > why do we need power_unit and time_unit if we only want to expose
> > > the
> > > energy counter?
> > AMD's Power Unit MSR provides identical information as Intel's,
> > including
> > time units, power units, and energy status units. By reusing the
> > check unit
> > method, we could avoid code duplication as well as easing future
> > enhance-
> > ment when AMD starts to support power limits.
> > > Plus, in rapl_init_domains(), PL1 is enabled for every RAPL Domain
> > > blindly, I'm not sure how this is handled on the AMD CPUs.
> > > Is PL1 invalidated by rapl_detect_powerlimit()? or is it still
> > > registered as a valid constraint into powercap sysfs I/F?
> > AMD's CORE_ENERGY_STAT MSR is like Intel's PP0_ENERGY_STATUS;
> > therefore, PL1 also always exists on AMD. rapl_detect_powerlimit()
> > correctly
> > markes the domain as monitoring-only after finding power limit MSRs
> > do not
> > exist.
> > > Currently, the code makes the assumption that there is only on
> > > power
> > > limit if priv->limits[domain_id] not set, we probably need to
> > > change
> > > this if we want to support RAPL domains with no power limit.
> > The existing code already supports RAPL domains with no power limit:
> > PL1 is
> > enabled when there is zero or one power limit,
> > rapl_detect_powerlimit() will then
> > mark if PL1 is monitoring-only if power limit MSRs do not exist. Both
> > AMD's RAPL
> > domains are monitoring-only and are correctly marked and handled.
> > > thanks,
> > > rui
> > > >  static const struct x86_cpu_id rapl_ids[] __initconst = {
> > > >       X86_MATCH_INTEL_FAM6_MODEL(SANDYBRIDGE,         &rapl_defau
> > > > lt
> > > > s_core),
> > > >       X86_MATCH_INTEL_FAM6_MODEL(SANDYBRIDGE_X,       &rapl_defau
> > > > lts_core),
> > > > @@ -1061,6 +1065,8 @@ static const struct x86_cpu_id rapl_ids[]
> > > > __initconst = {
> > > >
> > > >       X86_MATCH_INTEL_FAM6_MODEL(XEON_PHI_KNL,        &rapl_defau
> > > > lts_hsw_se
> > > > rver),
> > > >       X86_MATCH_INTEL_FAM6_MODEL(XEON_PHI_KNM,        &rapl_defau
> > > > lts_hsw_se
> > > > rver),
> > > > +
> > > > +     X86_MATCH_VENDOR_FAM(AMD, 0x17, &rapl_defaults_amd),
> > > >       {}
> > > >  };
> > > >  MODULE_DEVICE_TABLE(x86cpu, rapl_ids);
> > > > diff --git a/drivers/powercap/intel_rapl_msr.c
> > > > b/drivers/powercap/intel_rapl_msr.c
> > > > index a819b3b89b2f..78213d4b5b16 100644
> > > > --- a/drivers/powercap/intel_rapl_msr.c
> > > > +++ b/drivers/powercap/intel_rapl_msr.c
> > > > @@ -49,6 +49,14 @@ static struct rapl_if_priv rapl_msr_priv_intel
> > > > = {
> > > >       .limits[RAPL_DOMAIN_PLATFORM] = 2,
> > > >  };
> > > >
> > > > +static struct rapl_if_priv rapl_msr_priv_amd = {
> > > > +     .reg_unit = MSR_AMD_RAPL_POWER_UNIT,
> > > > +     .regs[RAPL_DOMAIN_PACKAGE] = {
> > > > +             0, MSR_AMD_PKG_ENERGY_STATUS, 0, 0, 0 },
> > > > +     .regs[RAPL_DOMAIN_PP0] = {
> > > > +             0, MSR_AMD_CORE_ENERGY_STATUS, 0, 0, 0 },
> > > > +};
> > > > +
> > > >  /* Handles CPU hotplug on multi-socket systems.
> > > >   * If a CPU goes online as the first CPU of the physical package
> > > >   * we add the RAPL package to the system. Similarly, when the
> > > > last
> > > > @@ -138,7 +146,17 @@ static int rapl_msr_probe(struct
> > > > platform_device
> > > > *pdev)
> > > >       const struct x86_cpu_id *id =
> > > > x86_match_cpu(pl4_support_ids);
> > > >       int ret;
> > > >
> > > > -     rapl_msr_priv = &rapl_msr_priv_intel;
> > > > +     switch (boot_cpu_data.x86_vendor) {
> > > > +     case X86_VENDOR_INTEL:
> > > > +             rapl_msr_priv = &rapl_msr_priv_intel;
> > > > +             break;
> > > > +     case X86_VENDOR_AMD:
> > > > +             rapl_msr_priv = &rapl_msr_priv_amd;
> > > > +             break;
> > > > +     default:
> > > > +             pr_err("intel-rapl does not support CPU vendor
> > > > %d\n",
> > > > boot_cpu_data.x86_vendor);
> > > > +             return -ENODEV;
> > > > +     }
> > > >       rapl_msr_priv->read_raw = rapl_msr_read_raw;
> > > >       rapl_msr_priv->write_raw = rapl_msr_write_raw;
> > > >
> > Best regards,
> > Victor Ding
>
Best regards,
Victor Ding