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authorSrinivas Pandruvada <srinivas.pandruvada@linux.intel.com>2017-01-18 21:29:15 +0300
committerDarren Hart <dvhart@linux.intel.com>2017-02-04 04:47:20 +0300
commit4ec567b8dda20d0129b60da63a472246f09e03d4 (patch)
tree70d00bc57305ec3502378515130e50727be5b4ea /drivers/platform
parenta28c7e93bf26f16948065dbbf4cbe3c457386f41 (diff)
downloadlinux-4ec567b8dda20d0129b60da63a472246f09e03d4.tar.xz
platform/x86: Support Turbo Boost Max 3.0 for non HWP systems
On platforms supporting Intel Turbo Boost Max Technology 3.0, the maximum turbo frequencies (turbo ratio) of some cores in a CPU package may be higher than the other cores in the same package. In that case, better performance can be achieved by making the scheduler prefer to run tasks on the CPUs with higher max turbo frequencies. On IntelĀ® Broadwell Xeon systems, it is optional to turn on HWP (Hardware P-States). When HWP is not turned on, the BIOS doesn't present required CPPC (Collaborative Processor Performance Control) tables. This table is used to get the per CPU core maximum performance ratio and inform scheduler (in cpufreq/intel_pstate driver). On such systems the maximum performance ratio can be read via over clocking (OC) mailbox interface for each CPU. This interface is not architectural and can change for every model of processors. This driver reads maximum performance ratio of each CPU and set up the scheduler priority metrics. In this way scheduler can prefer CPU with higher performance to schedule tasks. Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> Signed-off-by: Darren Hart <dvhart@linux.intel.com>
Diffstat (limited to 'drivers/platform')
-rw-r--r--drivers/platform/x86/Kconfig10
-rw-r--r--drivers/platform/x86/Makefile1
-rw-r--r--drivers/platform/x86/intel_turbo_max_3.c152
3 files changed, 163 insertions, 0 deletions
diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
index e4758d7ab602..d9748a881798 100644
--- a/drivers/platform/x86/Kconfig
+++ b/drivers/platform/x86/Kconfig
@@ -1074,4 +1074,14 @@ config MLX_CPLD_PLATFORM
This driver handles hot-plug events for the power suppliers, power
cables and fans on the wide range Mellanox IB and Ethernet systems.
+config INTEL_TURBO_MAX_3
+ bool "Intel Turbo Boost Max Technology 3.0 enumeration driver"
+ depends on X86_64 && SCHED_MC_PRIO
+ ---help---
+ This driver reads maximum performance ratio of each CPU and set up
+ the scheduler priority metrics. In this way scheduler can prefer
+ CPU with higher performance to schedule tasks.
+ This driver is only required when the system is not using Hardware
+ P-States (HWP). In HWP mode, priority can be read from ACPI tables.
+
endif # X86_PLATFORM_DEVICES
diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
index d4111f0f8a78..cde7b4fdf5d6 100644
--- a/drivers/platform/x86/Makefile
+++ b/drivers/platform/x86/Makefile
@@ -76,3 +76,4 @@ obj-$(CONFIG_INTEL_TELEMETRY) += intel_telemetry_core.o \
obj-$(CONFIG_INTEL_PMC_CORE) += intel_pmc_core.o
obj-$(CONFIG_MLX_PLATFORM) += mlx-platform.o
obj-$(CONFIG_MLX_CPLD_PLATFORM) += mlxcpld-hotplug.o
+obj-$(CONFIG_INTEL_TURBO_MAX_3) += intel_turbo_max_3.o
diff --git a/drivers/platform/x86/intel_turbo_max_3.c b/drivers/platform/x86/intel_turbo_max_3.c
new file mode 100644
index 000000000000..0103f5b32e34
--- /dev/null
+++ b/drivers/platform/x86/intel_turbo_max_3.c
@@ -0,0 +1,152 @@
+/*
+ * Intel Turbo Boost Max Technology 3.0 legacy (non HWP) enumeration driver
+ * Copyright (c) 2017, Intel Corporation.
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/cpuhotplug.h>
+#include <linux/cpufeature.h>
+#include <asm/cpu_device_id.h>
+#include <asm/intel-family.h>
+
+#define MSR_OC_MAILBOX 0x150
+#define MSR_OC_MAILBOX_CMD_OFFSET 32
+#define MSR_OC_MAILBOX_RSP_OFFSET 32
+#define MSR_OC_MAILBOX_BUSY_BIT 63
+#define OC_MAILBOX_FC_CONTROL_CMD 0x1C
+
+/*
+ * Typical latency to get mail box response is ~3us, It takes +3 us to
+ * process reading mailbox after issuing mailbox write on a Broadwell 3.4 GHz
+ * system. So for most of the time, the first mailbox read should have the
+ * response, but to avoid some boundary cases retry twice.
+ */
+#define OC_MAILBOX_RETRY_COUNT 2
+
+static int get_oc_core_priority(unsigned int cpu)
+{
+ u64 value, cmd = OC_MAILBOX_FC_CONTROL_CMD;
+ int ret, i;
+
+ /* Issue favored core read command */
+ value = cmd << MSR_OC_MAILBOX_CMD_OFFSET;
+ /* Set the busy bit to indicate OS is trying to issue command */
+ value |= BIT_ULL(MSR_OC_MAILBOX_BUSY_BIT);
+ ret = wrmsrl_safe(MSR_OC_MAILBOX, value);
+ if (ret) {
+ pr_debug("cpu %d OC mailbox write failed\n", cpu);
+ return ret;
+ }
+
+ for (i = 0; i < OC_MAILBOX_RETRY_COUNT; ++i) {
+ ret = rdmsrl_safe(MSR_OC_MAILBOX, &value);
+ if (ret) {
+ pr_debug("cpu %d OC mailbox read failed\n", cpu);
+ break;
+ }
+
+ if (value & BIT_ULL(MSR_OC_MAILBOX_BUSY_BIT)) {
+ pr_debug("cpu %d OC mailbox still processing\n", cpu);
+ ret = -EBUSY;
+ continue;
+ }
+
+ if ((value >> MSR_OC_MAILBOX_RSP_OFFSET) & 0xff) {
+ pr_debug("cpu %d OC mailbox cmd failed\n", cpu);
+ ret = -ENXIO;
+ break;
+ }
+
+ ret = value & 0xff;
+ pr_debug("cpu %d max_ratio %d\n", cpu, ret);
+ break;
+ }
+
+ return ret;
+}
+
+/*
+ * The work item is needed to avoid CPU hotplug locking issues. The function
+ * itmt_legacy_set_priority() is called from CPU online callback, so can't
+ * call sched_set_itmt_support() from there as this function will aquire
+ * hotplug locks in its path.
+ */
+static void itmt_legacy_work_fn(struct work_struct *work)
+{
+ sched_set_itmt_support();
+}
+
+static DECLARE_WORK(sched_itmt_work, itmt_legacy_work_fn);
+
+static int itmt_legacy_cpu_online(unsigned int cpu)
+{
+ static u32 max_highest_perf = 0, min_highest_perf = U32_MAX;
+ int priority;
+
+ priority = get_oc_core_priority(cpu);
+ if (priority < 0)
+ return 0;
+
+ sched_set_itmt_core_prio(priority, cpu);
+
+ /* Enable ITMT feature when a core with different priority is found */
+ if (max_highest_perf <= min_highest_perf) {
+ if (priority > max_highest_perf)
+ max_highest_perf = priority;
+
+ if (priority < min_highest_perf)
+ min_highest_perf = priority;
+
+ if (max_highest_perf > min_highest_perf)
+ schedule_work(&sched_itmt_work);
+ }
+
+ return 0;
+}
+
+#define ICPU(model) { X86_VENDOR_INTEL, 6, model, X86_FEATURE_ANY, }
+
+static const struct x86_cpu_id itmt_legacy_cpu_ids[] = {
+ ICPU(INTEL_FAM6_BROADWELL_X),
+ {}
+};
+MODULE_DEVICE_TABLE(x86cpu, itmt_legacy_cpu_ids);
+
+static int __init itmt_legacy_init(void)
+{
+ const struct x86_cpu_id *id;
+ int ret;
+
+ id = x86_match_cpu(itmt_legacy_cpu_ids);
+ if (!id)
+ return -ENODEV;
+
+ if (boot_cpu_has(X86_FEATURE_HWP))
+ return -ENODEV;
+
+ ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
+ "platform/x86/turbo_max_3:online",
+ itmt_legacy_cpu_online, NULL);
+ if (ret < 0)
+ return ret;
+
+ return 0;
+}
+late_initcall(itmt_legacy_init)
+
+MODULE_DESCRIPTION("Intel Turbo Boost Max 3.0 enumeration driver");
+MODULE_AUTHOR("Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>");
+MODULE_LICENSE("GPL v2");