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From: Giovanni Gherdovich <ggherdovich@suse.cz>
To: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
	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>,
	Giovanni Gherdovich <ggherdovich@suse.cz>
Subject: [PATCH v4 4/6] x86,sched: Add support for frequency invariance on ATOM_GOLDMONT*
Date: Wed, 13 Nov 2019 13:46:52 +0100
Message-ID: <20191113124654.18122-5-ggherdovich@suse.cz> (raw)
In-Reply-To: <20191113124654.18122-1-ggherdovich@suse.cz>

The scheduler needs the ratio freq_curr/freq_max for frequency-invariant
accounting. On GOLDMONT (aka Apollo Lake), GOLDMONT_D (aka Denverton) and
GOLDMONT_PLUS CPUs (aka Gemini Lake) set freq_max to the highest frequency
reported by the CPU.

The encoding of turbo ratios for GOLDMONT* is identical to the one for
SKYLAKE_X, but we treat the Atom case apart because we want to set freq_max to
a higher value, thus the ratio freq_curr/freq_max to be lower, leading to more
conservative frequency selections (favoring power efficiency).

Signed-off-by: Giovanni Gherdovich <ggherdovich@suse.cz>
---
 arch/x86/kernel/smpboot.c | 32 +++++++++++++++++++++++++++++---
 1 file changed, 29 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 0e79dcc03ae4..4d192abf337d 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1795,6 +1795,10 @@ void native_play_dead(void)
  * which would ignore the entire turbo range (a conspicuous part, making
  * freq_curr/freq_max always maxed out).
  *
+ * An exception to the heuristic above is the Atom uarch, where we choose the
+ * highest turbo level for freq_max since Atom's are generally oriented towards
+ * power efficiency.
+ *
  * Setting freq_max to anything less than the 1C turbo ratio makes the ratio
  * freq_curr / freq_max to eventually grow >1, in which case we clip it to 1.
  */
@@ -1841,6 +1845,27 @@ static const struct x86_cpu_id has_glm_turbo_ratio_limits[] = {
 	{}
 };
 
+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;
@@ -1962,7 +1987,6 @@ static void intel_set_cpu_max_freq(void)
 	/*
 	 * TODO: add support for:
 	 *
-	 * - Atom Goldmont
 	 * - Atom Silvermont
 	 *
 	 * which all now get by default arch_max_freq = SCHED_CAPACITY_SCALE
@@ -1970,10 +1994,12 @@ static void intel_set_cpu_max_freq(void)
 
 	u64 ratio = 1, turbo_ratio = 1;
 
-	if (turbo_disabled() ||
-		x86_match_cpu(has_glm_turbo_ratio_limits))
+	if (turbo_disabled())
 		return;
 
+	if (glm_set_cpu_max_freq(&ratio, &turbo_ratio))
+		goto set_value;
+
 	if (knl_set_cpu_max_freq(&ratio, &turbo_ratio))
 		goto set_value;
 
-- 
2.16.4


  parent reply index

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 ` Giovanni Gherdovich [this message]
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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