From: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
To: Giovanni Gherdovich <ggherdovich@suse.cz>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Borislav Petkov <bp@suse.de>, Len Brown <lenb@kernel.org>,
"Rafael J . Wysocki" <rjw@rjwysocki.net>
Cc: x86@kernel.org, linux-pm@vger.kernel.org,
linux-kernel@vger.kernel.org,
Mel Gorman <mgorman@techsingularity.net>,
Matt Fleming <matt@codeblueprint.co.uk>,
Viresh Kumar <viresh.kumar@linaro.org>,
Juri Lelli <juri.lelli@redhat.com>, Paul Turner <pjt@google.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Quentin Perret <qperret@qperret.net>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Doug Smythies <dsmythies@telus.net>
Subject: Re: [PATCH v4 5/6] x86,sched: Add support for frequency invariance on ATOM
Date: Wed, 13 Nov 2019 08:50:03 -0800 [thread overview]
Message-ID: <64baa18f7cd6066cc50360928d77504c1b68773e.camel@linux.intel.com> (raw)
In-Reply-To: <20191113124654.18122-6-ggherdovich@suse.cz>
On Wed, 2019-11-13 at 13:46 +0100, Giovanni Gherdovich wrote:
> The scheduler needs the ratio freq_curr/freq_max for frequency-
> invariant
> accounting. On all ATOM CPUs prior to Goldmont, set freq_max to the
> 1-core
> turbo ratio.
>
> We intended to perform tests validating that this patch doesn't
> regress in
> terms of energy efficiency, given that this is the primary concern on
> Atom
> processors. Alas, we found out that turbostat doesn't support reading
> RAPL
> interfaces on our test machine (Airmont), and we don't have external
> equipment
> to measure power consumption; all we have is the performance results
> of the
> benchmarks we ran.
>
I can run some benchmarks on this.
Thanks,
Srinivas
> Test machine:
>
> Platform : Dell Wyse 3040 Thin Client[1]
> CPU Model : Intel Atom x5-Z8350 (aka Cherry Trail, aka Airmont)
> Fam/Mod/Ste : 6:76:4
> Topology : 1 socket, 4 cores / 4 threads
> Memory : 2G
> Storage : onboard flash, XFS filesystem
>
> [1]
> https://www.dell.com/en-us/work/shop/wyse-endpoints-and-software/wyse-3040-thin-client/spd/wyse-3040-thin-client
>
> Base frequency and available turbo levels (MHz):
>
> Min Operating Freq 266 |***
> Low Freq Mode 800 |********
> Base Freq 2400 |************************
> 4 Cores 2800 |****************************
> 3 Cores 2800 |****************************
> 2 Cores 3200 |********************************
> 1 Core 3200 |********************************
>
> Tested kernels:
>
> Baseline : v5.4-rc1, intel_pstate
> passive, schedutil
> Comparison #1 : v5.4-rc1, intel_pstate active
> , powersave
> Comparison #2 : v5.4-rc1, this patch, intel_pstate
> passive, schedutil
>
> tbench, hackbench and kernbench performed the same under all three
> kernels;
> dbench ran faster with intel_pstate/powersave and the git unit tests
> were a
> lot faster with intel_pstate/powersave and invariant schedutil wrt
> the
> baseline. Not that any of this is terrbily interesting anyway, one
> doesn't buy
> an Atom system to go fast. Power consumption regressions aren't
> expected but
> we lack the equipment to make that measurement. Turbostat seems to
> think that
> reading RAPL on this machine isn't a good idea and we're trusting
> that
> decision.
>
> comparison ratio of performance with baseline; 1.00 means neutral,
> lower is better:
>
> I_PSTATE FREQ-INV
> ----------------------------------------
> dbench 0.90 ~
> kernbench 0.98 0.97
> gitsource 0.63 0.43
>
> Signed-off-by: Giovanni Gherdovich <ggherdovich@suse.cz>
> ---
> arch/x86/kernel/smpboot.c | 29 +++++++++++++++++++++--------
> 1 file changed, 21 insertions(+), 8 deletions(-)
>
> diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
> index 4d192abf337d..8988177064be 100644
> --- a/arch/x86/kernel/smpboot.c
> +++ b/arch/x86/kernel/smpboot.c
> @@ -1821,6 +1821,24 @@ static bool turbo_disabled(void)
> return (misc_en & MSR_IA32_MISC_ENABLE_TURBO_DISABLE);
> }
>
> +static bool slv_set_cpu_max_freq(u64 *ratio, u64 *turbo_ratio)
> +{
> + int err;
> +
> + err = rdmsrl_safe(MSR_ATOM_CORE_RATIOS, ratio);
> + if (err)
> + return false;
> +
> + err = rdmsrl_safe(MSR_ATOM_CORE_TURBO_RATIOS, turbo_ratio);
> + if (err)
> + return false;
> +
> + *ratio = (*ratio >> 16) & 0x3F; /* max P state ratio */
> + *turbo_ratio = *turbo_ratio & 0x3F; /* 1C turbo ratio */
> +
> + return true;
> +}
> +
> #include <asm/cpu_device_id.h>
> #include <asm/intel-family.h>
>
> @@ -1984,19 +2002,14 @@ static bool core_set_cpu_max_freq(u64 *ratio,
> u64 *turbo_ratio)
>
> static void intel_set_cpu_max_freq(void)
> {
> - /*
> - * TODO: add support for:
> - *
> - * - Atom Silvermont
> - *
> - * which all now get by default arch_max_freq =
> SCHED_CAPACITY_SCALE
> - */
> -
> u64 ratio = 1, turbo_ratio = 1;
>
> if (turbo_disabled())
> return;
>
> + if (slv_set_cpu_max_freq(&ratio, &turbo_ratio))
> + goto set_value;
> +
> if (glm_set_cpu_max_freq(&ratio, &turbo_ratio))
> goto set_value;
>
next prev parent reply other threads:[~2019-11-13 16:50 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-13 12:46 [PATCH v4 0/6] Add support for frequency invariance for (some) x86 Giovanni Gherdovich
2019-11-13 12:46 ` [PATCH v4 1/6] x86,sched: Add support for frequency invariance Giovanni Gherdovich
2019-11-24 7:49 ` Doug Smythies
2019-11-25 8:16 ` Doug Smythies
2019-11-25 9:16 ` Mel Gorman
2019-11-25 16:06 ` Giovanni Gherdovich
2019-11-26 5:59 ` Doug Smythies
2019-11-26 15:20 ` Giovanni Gherdovich
2019-11-27 7:32 ` Doug Smythies
2019-11-28 22:48 ` Doug Smythies
2019-12-19 10:48 ` Qais Yousef
2019-12-23 7:47 ` Doug Smythies
2019-12-23 14:07 ` Qais Yousef
2019-12-23 14:40 ` Qais Yousef
2019-12-23 16:34 ` Doug Smythies
2019-12-23 19:10 ` Qais Yousef
2019-12-24 1:16 ` Doug Smythies
2019-12-24 11:08 ` Qais Yousef
2019-12-02 16:34 ` Ionela Voinescu
2019-12-06 11:57 ` Giovanni Gherdovich
2019-12-18 19:34 ` Peter Zijlstra
2019-12-19 20:27 ` Giovanni Gherdovich
2019-11-13 12:46 ` [PATCH v4 2/6] x86,sched: Add support for frequency invariance on SKYLAKE_X Giovanni Gherdovich
2019-12-18 20:06 ` Peter Zijlstra
2019-12-19 20:29 ` Giovanni Gherdovich
2019-11-13 12:46 ` [PATCH v4 3/6] x86,sched: Add support for frequency invariance on XEON_PHI_KNL/KNM Giovanni Gherdovich
2019-12-18 20:22 ` Peter Zijlstra
2019-12-19 20:32 ` Giovanni Gherdovich
2019-11-13 12:46 ` [PATCH v4 4/6] x86,sched: Add support for frequency invariance on ATOM_GOLDMONT* Giovanni Gherdovich
2019-11-13 12:46 ` [PATCH v4 5/6] x86,sched: Add support for frequency invariance on ATOM Giovanni Gherdovich
2019-11-13 16:50 ` Srinivas Pandruvada [this message]
2019-11-15 10:34 ` Giovanni Gherdovich
2019-11-13 12:46 ` [PATCH v4 6/6] x86: intel_pstate: handle runtime turbo disablement/enablement in freq. invariance Giovanni Gherdovich
2019-12-18 20:37 ` [PATCH v4 0/6] Add support for frequency invariance for (some) x86 Peter Zijlstra
2019-12-19 20:33 ` Giovanni Gherdovich
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