From: Peter Zijlstra <peterz@infradead.org>
To: Giovanni Gherdovich <ggherdovich@suse.cz>
Cc: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@suse.de>,
Len Brown <lenb@kernel.org>,
"Rafael J . Wysocki" <rjw@rjwysocki.net>,
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 2/6] x86,sched: Add support for frequency invariance on SKYLAKE_X
Date: Wed, 18 Dec 2019 21:06:24 +0100 [thread overview]
Message-ID: <20191218200624.GI11457@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <20191113124654.18122-3-ggherdovich@suse.cz>
On Wed, Nov 13, 2019 at 01:46:50PM +0100, Giovanni Gherdovich wrote:
> The scheduler needs the ratio freq_curr/freq_max for frequency-invariant
> accounting. On SKYLAKE_X CPUs set freq_max to the highest frequency that can
> be sustained by a group of at least 4 cores.
>
> From the changelog of commit 31e07522be56 ("tools/power turbostat: fix
> decoding for GLM, DNV, SKX turbo-ratio limits"):
>
> > Newer processors do not hard-code the the number of cpus in each bin
> > to {1, 2, 3, 4, 5, 6, 7, 8} Rather, they can specify any number
> > of CPUS in each of the 8 bins:
> >
> > eg.
> >
> > ...
> > 37 * 100.0 = 3600.0 MHz max turbo 4 active cores
> > 38 * 100.0 = 3700.0 MHz max turbo 3 active cores
> > 39 * 100.0 = 3800.0 MHz max turbo 2 active cores
> > 39 * 100.0 = 3900.0 MHz max turbo 1 active cores
> >
> > could now look something like this:
> >
> > ...
> > 37 * 100.0 = 3600.0 MHz max turbo 16 active cores
> > 38 * 100.0 = 3700.0 MHz max turbo 8 active cores
> > 39 * 100.0 = 3800.0 MHz max turbo 4 active cores
> > 39 * 100.0 = 3900.0 MHz max turbo 2 active cores
>
> This encoding of turbo levels applies to both SKYLAKE_X and GOLDMONT/GOLDMONT_D,
> but we treat these two classes in separate commits because their freq_max
> values need to be different. For SKX we prefer a lower freq_max in the ratio
> freq_curr/freq_max, allowing load and utilization to overshoot and the
> schedutil governor to be more performance-oriented. Models from the Atom
> series (such as GOLDMONT*) are handled in a forthcoming commit as they have to
> favor power-efficiency over performance.
Can we at least use a single function to decode both? A little like the
below. I'm not married to the naming, but I think it is a little silly
to have 2 different functions to decode the exact same MSRs.
(one could even go as far as to make a boot param to override the {1,4}
default core count for these things)
---
Index: linux-2.6/arch/x86/kernel/smpboot.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/smpboot.c
+++ linux-2.6/arch/x86/kernel/smpboot.c
@@ -1863,27 +1863,6 @@ static const struct x86_cpu_id has_glm_t
{}
};
-static bool glm_set_cpu_max_freq(u64 *ratio, u64 *turbo_ratio)
-{
- int err;
-
- if (!x86_match_cpu(has_glm_turbo_ratio_limits))
- return false;
-
- err = rdmsrl_safe(MSR_PLATFORM_INFO, ratio);
- if (err)
- return false;
-
- err = rdmsrl_safe(MSR_TURBO_RATIO_LIMIT, turbo_ratio);
- if (err)
- return false;
-
- *ratio = (*ratio >> 8) & 0xFF; /* max P state ratio */
- *turbo_ratio = *turbo_ratio & 0xFF; /* highest turbo ratio */
-
- return true;
-}
-
static int get_knl_turbo_ratio(u64 *turbo_ratio)
{
u64 msr;
@@ -1933,53 +1912,35 @@ static bool knl_set_cpu_max_freq(u64 *ra
return true;
}
-static int get_turbo_ratio_group(u64 *turbo_ratio)
+static bool skx_set_cpu_max_freq(u64 *ratio, u64 *turbo_ratio, int size)
{
- u64 ratio, core_counts;
- u32 group_size = 0;
- int err, i, found = 0;
+ u64 ratios, counts;
+ u32 group_size;
+ int err, i;
- err = rdmsrl_safe(MSR_TURBO_RATIO_LIMIT, &ratio);
- if (err)
- return err;
-
- err = rdmsrl_safe(MSR_TURBO_RATIO_LIMIT1, &core_counts);
+ err = rdmsrl_safe(MSR_PLATFORM_INFO, ratio);
if (err)
- return err;
-
- for (i = 0; i < 64; i += 8) {
- group_size = (core_counts >> i) & 0xFF;
- if (group_size >= 4) {
- *turbo_ratio = (ratio >> i) & 0xFF;
- found = 1;
- break;
- }
- }
-
- if (!found)
- return 1;
-
- return 0;
-}
-
-static bool skx_set_cpu_max_freq(u64 *ratio, u64 *turbo_ratio)
-{
- int err;
-
- if (!x86_match_cpu(has_skx_turbo_ratio_limits))
return false;
- err = rdmsrl_safe(MSR_PLATFORM_INFO, ratio);
+ *ratio = (*ratio >> 8) & 0xFF; /* max P state ratio */
+
+ err = rdmsrl_safe(MSR_TURBO_RATIO_LIMIT, &ratios);
if (err)
return false;
- err = get_turbo_ratio_group(turbo_ratio); /* 4C (circa) turbo ratio */
+ err = rdmsrl_safe(MSR_TURBO_RATIO_LIMIT1, &counts);
if (err)
return false;
- *ratio = (*ratio >> 8) & 0xFF; /* max P state ratio */
+ for (i = 0; i < 64; i += 8) {
+ group_size = (counts >> i) & 0xFF;
+ if (group_size >= size) {
+ *turbo_ratio = (ratios >> i) & 0xFF;
+ return true;
+ }
+ }
- return true;
+ return false;
}
static bool core_set_cpu_max_freq(u64 *ratio, u64 *turbo_ratio)
@@ -2010,13 +1971,15 @@ static void intel_set_cpu_max_freq(void)
if (slv_set_cpu_max_freq(&ratio, &turbo_ratio))
goto set_value;
- if (glm_set_cpu_max_freq(&ratio, &turbo_ratio))
+ if (x86_match_cpu(has_glm_turbo_ratio_limits) &&
+ skx_set_cpu_max_freq(&ratio, &turbo_ratio, 1))
goto set_value;
if (knl_set_cpu_max_freq(&ratio, &turbo_ratio))
goto set_value;
- if (skx_set_cpu_max_freq(&ratio, &turbo_ratio))
+ if (x86_match_cpu(has_skx_turbo_ratio_limits) &&
+ skx_set_cpu_max_freq(&ratio, &turbo_ratio, 4))
goto set_value;
core_set_cpu_max_freq(&ratio, &turbo_ratio);
next prev parent reply other threads:[~2019-12-18 20:06 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 [this message]
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
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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