[tip:x86/cpu] powernow-k8: Add core performance boost support

From: tip-bot for Borislav Petkov
Date: Fri Apr 09 2010 - 18:19:36 EST

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Commit-ID: 73860c6b2fd159a35637e233d735e36887c266ad
Gitweb: http://git.kernel.org/tip/73860c6b2fd159a35637e233d735e36887c266ad
Author: Borislav Petkov <borislav.petkov@xxxxxxx>
AuthorDate: Wed, 31 Mar 2010 21:56:42 +0200
Committer: H. Peter Anvin <hpa@xxxxxxxxx>
CommitDate: Fri, 9 Apr 2010 14:05:43 -0700

powernow-k8: Add core performance boost support

Starting with F10h, revE, AMD processors add support for a dynamic
core boosting feature called Core Performance Boost. When a specific
condition is present, a subset of the cores on a system are boosted
beyond their P0 operating frequency to speed up the performance of
single-threaded applications.

In the normal case, the system comes out of reset with core boosting
enabled. This patch adds a sysfs knob with which core boosting can be
switched on or off for benchmarking purposes.

While at it, make the CPB code hotplug-aware so that taking cores
offline wouldn't interfere with boosting the remaining online cores.
Furthermore, add cpu_online_mask hotplug protection as suggested by
Andrew.

Finally, cleanup the driver init codepath and update copyrights.

Signed-off-by: Borislav Petkov <borislav.petkov@xxxxxxx>
LKML-Reference: <1270065406-1814-3-git-send-email-bp@xxxxxxxxx>
Reviewed-by: Thomas Renninger <trenn@xxxxxxx>
Signed-off-by: H. Peter Anvin <hpa@xxxxxxxxx>
---
arch/x86/kernel/cpu/cpufreq/powernow-k8.c | 161 +++++++++++++++++++++++++++--
arch/x86/kernel/cpu/cpufreq/powernow-k8.h | 2 -
2 files changed, 151 insertions(+), 12 deletions(-)

diff --git a/arch/x86/kernel/cpu/cpufreq/powernow-k8.c b/arch/x86/kernel/cpu/cpufreq/powernow-k8.c
index d360b56..74ca34b 100644
--- a/arch/x86/kernel/cpu/cpufreq/powernow-k8.c
+++ b/arch/x86/kernel/cpu/cpufreq/powernow-k8.c
@@ -1,6 +1,5 @@
-
/*
- * (c) 2003-2006 Advanced Micro Devices, Inc.
+ * (c) 2003-2010 Advanced Micro Devices, Inc.
* Your use of this code is subject to the terms and conditions of the
* GNU general public license version 2. See "COPYING" or
* http://www.gnu.org/licenses/gpl.html
@@ -54,6 +53,10 @@ static DEFINE_PER_CPU(struct powernow_k8_data *, powernow_data);

static int cpu_family = CPU_OPTERON;

+/* core performance boost */
+static bool cpb_capable, cpb_enabled;
+static struct msr __percpu *msrs;
+
#ifndef CONFIG_SMP
static inline const struct cpumask *cpu_core_mask(int cpu)
{
@@ -1393,8 +1396,77 @@ out:
return khz;
}

+static void _cpb_toggle_msrs(bool t)
+{
+ int cpu;
+
+ get_online_cpus();
+
+ rdmsr_on_cpus(cpu_online_mask, MSR_K7_HWCR, msrs);
+
+ for_each_cpu(cpu, cpu_online_mask) {
+ struct msr *reg = per_cpu_ptr(msrs, cpu);
+ if (t)
+ reg->l &= ~BIT(25);
+ else
+ reg->l |= BIT(25);
+ }
+ wrmsr_on_cpus(cpu_online_mask, MSR_K7_HWCR, msrs);
+
+ put_online_cpus();
+}
+
+/*
+ * Switch on/off core performance boosting.
+ *
+ * 0=disable
+ * 1=enable.
+ */
+static void cpb_toggle(bool t)
+{
+ if (!cpb_capable)
+ return;
+
+ if (t && !cpb_enabled) {
+ cpb_enabled = true;
+ _cpb_toggle_msrs(t);
+ printk(KERN_INFO PFX "Core Boosting enabled.\n");
+ } else if (!t && cpb_enabled) {
+ cpb_enabled = false;
+ _cpb_toggle_msrs(t);
+ printk(KERN_INFO PFX "Core Boosting disabled.\n");
+ }
+}
+
+static ssize_t store_cpb(struct cpufreq_policy *policy, const char *buf,
+ size_t count)
+{
+ int ret = -EINVAL;
+ unsigned long val = 0;
+
+ ret = strict_strtoul(buf, 10, &val);
+ if (!ret && (val == 0 || val == 1) && cpb_capable)
+ cpb_toggle(val);
+ else
+ return -EINVAL;
+
+ return count;
+}
+
+static ssize_t show_cpb(struct cpufreq_policy *policy, char *buf)
+{
+ return sprintf(buf, "%u\n", cpb_enabled);
+}
+
+#define define_one_rw(_name) \
+static struct freq_attr _name = \
+__ATTR(_name, 0644, show_##_name, store_##_name)
+
+define_one_rw(cpb);
+
static struct freq_attr *powernow_k8_attr[] = {
&cpufreq_freq_attr_scaling_available_freqs,
+ &cpb,
NULL,
};

@@ -1410,10 +1482,51 @@ static struct cpufreq_driver cpufreq_amd64_driver = {
.attr = powernow_k8_attr,
};

+/*
+ * Clear the boost-disable flag on the CPU_DOWN path so that this cpu
+ * cannot block the remaining ones from boosting. On the CPU_UP path we
+ * simply keep the boost-disable flag in sync with the current global
+ * state.
+ */
+static int __cpuinit cpb_notify(struct notifier_block *nb, unsigned long action,
+ void *hcpu)
+{
+ unsigned cpu = (long)hcpu;
+ u32 lo, hi;
+
+ switch (action) {
+ case CPU_UP_PREPARE:
+ case CPU_UP_PREPARE_FROZEN:
+
+ if (!cpb_enabled) {
+ rdmsr_on_cpu(cpu, MSR_K7_HWCR, &lo, &hi);
+ lo |= BIT(25);
+ wrmsr_on_cpu(cpu, MSR_K7_HWCR, lo, hi);
+ }
+ break;
+
+ case CPU_DOWN_PREPARE:
+ case CPU_DOWN_PREPARE_FROZEN:
+ rdmsr_on_cpu(cpu, MSR_K7_HWCR, &lo, &hi);
+ lo &= ~BIT(25);
+ wrmsr_on_cpu(cpu, MSR_K7_HWCR, lo, hi);
+ break;
+
+ default:
+ break;
+ }
+
+ return NOTIFY_OK;
+}
+
+static struct notifier_block __cpuinitdata cpb_nb = {
+ .notifier_call = cpb_notify,
+};
+
/* driver entry point for init */
static int __cpuinit powernowk8_init(void)
{
- unsigned int i, supported_cpus = 0;
+ unsigned int i, supported_cpus = 0, cpu;

for_each_online_cpu(i) {
int rc;
@@ -1422,15 +1535,36 @@ static int __cpuinit powernowk8_init(void)
supported_cpus++;
}

- if (supported_cpus == num_online_cpus()) {
- printk(KERN_INFO PFX "Found %d %s "
- "processors (%d cpu cores) (" VERSION ")\n",
- num_online_nodes(),
- boot_cpu_data.x86_model_id, supported_cpus);
- return cpufreq_register_driver(&cpufreq_amd64_driver);
+ if (supported_cpus != num_online_cpus())
+ return -ENODEV;
+
+ printk(KERN_INFO PFX "Found %d %s (%d cpu cores) (" VERSION ")\n",
+ num_online_nodes(), boot_cpu_data.x86_model_id, supported_cpus);
+
+ if (boot_cpu_has(X86_FEATURE_CPB)) {
+
+ cpb_capable = true;
+
+ register_cpu_notifier(&cpb_nb);
+
+ msrs = msrs_alloc();
+ if (!msrs) {
+ printk(KERN_ERR "%s: Error allocating msrs!\n", __func__);
+ return -ENOMEM;
+ }
+
+ rdmsr_on_cpus(cpu_online_mask, MSR_K7_HWCR, msrs);
+
+ for_each_cpu(cpu, cpu_online_mask) {
+ struct msr *reg = per_cpu_ptr(msrs, cpu);
+ cpb_enabled |= !(!!(reg->l & BIT(25)));
+ }
+
+ printk(KERN_INFO PFX "Core Performance Boosting: %s.\n",
+ (cpb_enabled ? "on" : "off"));
}

- return -ENODEV;
+ return cpufreq_register_driver(&cpufreq_amd64_driver);
}

/* driver entry point for term */
@@ -1438,6 +1572,13 @@ static void __exit powernowk8_exit(void)
{
dprintk("exit\n");

+ if (boot_cpu_has(X86_FEATURE_CPB)) {
+ msrs_free(msrs);
+ msrs = NULL;
+
+ unregister_cpu_notifier(&cpb_nb);
+ }
+
cpufreq_unregister_driver(&cpufreq_amd64_driver);
}

diff --git a/arch/x86/kernel/cpu/cpufreq/powernow-k8.h b/arch/x86/kernel/cpu/cpufreq/powernow-k8.h
index 02ce824..df3529b 100644
--- a/arch/x86/kernel/cpu/cpufreq/powernow-k8.h
+++ b/arch/x86/kernel/cpu/cpufreq/powernow-k8.h
@@ -5,7 +5,6 @@
* http://www.gnu.org/licenses/gpl.html
*/

-
enum pstate {
HW_PSTATE_INVALID = 0xff,
HW_PSTATE_0 = 0,
@@ -55,7 +54,6 @@ struct powernow_k8_data {
struct cpumask *available_cores;
};

-
/* processor's cpuid instruction support */
#define CPUID_PROCESSOR_SIGNATURE 1 /* function 1 */
#define CPUID_XFAM 0x0ff00000 /* extended family */
--
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Next message: tip-bot for Borislav Petkov: "[tip:x86/cpu] x86: Unify APERF/MPERF support"
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