[PATCH v1 0/4] add uncore api to be called through l3fwd-power

[PATCH v1 0/4] add uncore api to be called through l3fwd-power

[tadhgkearney]

This is targeting 22.11 and aims to add an API to DPDK to allow uncore frequency adjustment.
This will be called through the l3fwd-power app, and gives the ability to set the min, max and specific frequency index that you want the uncore to be at.

tadhgkearney (4):
  power: add uncore api to power library
  l3fwd-power: add option to call uncore api
  test/power: add unit tests for uncore api
  config: add uncore defines for x86

 app/test/meson.build                          |   2 +
 app/test/test_power_uncore.c                  | 245 +++++++++++
 config/x86/meson.build                        |   2 +
 doc/guides/prog_guide/power_man.rst           |  27 ++
 .../sample_app_ug/l3_forward_power_man.rst    |  28 ++
 examples/l3fwd-power/main.c                   | 154 ++++++-
 lib/power/meson.build                         |   2 +
 lib/power/rte_power_uncore.c                  | 401 ++++++++++++++++++
 lib/power/rte_power_uncore.h                  | 159 +++++++
 lib/power/version.map                         |   7 +
 10 files changed, 1018 insertions(+), 1 deletion(-)
 create mode 100644 app/test/test_power_uncore.c
 create mode 100644 lib/power/rte_power_uncore.c
 create mode 100644 lib/power/rte_power_uncore.h

-- 
2.25.1

[PATCH v1 1/4] power: add uncore api to power library

[tadhgkearney]

Add api to allow uncore frequency adjustment. This is done through manipulating related sysfs entries to adjust the min/max uncore values.
Seven api's are being added that are all public and experimental. Power man docs updated to reflect this.

Signed-off-by: tadhgkearney <tadhg.kearney@intel.com>
---
 doc/guides/prog_guide/power_man.rst |  27 ++
 lib/power/meson.build               |   2 +
 lib/power/rte_power_uncore.c        | 401 ++++++++++++++++++++++++++++
 lib/power/rte_power_uncore.h        | 151 +++++++++++
 lib/power/version.map               |   7 +
 5 files changed, 588 insertions(+)
 create mode 100644 lib/power/rte_power_uncore.c
 create mode 100644 lib/power/rte_power_uncore.h

diff --git a/doc/guides/prog_guide/power_man.rst b/doc/guides/prog_guide/power_man.rst
index 98cfd3c1f3..a512bca0b6 100644
--- a/doc/guides/prog_guide/power_man.rst
+++ b/doc/guides/prog_guide/power_man.rst
@@ -276,6 +276,33 @@ API Overview for Ethernet PMD Power Management
 * **Set Scaling Max Freq**: Set the maximum frequency (kHz) to be used in Frequency
   Scaling mode.
 
+Uncore API
+----------
+
+Abstract
+~~~~~~~~
+Up to 60% power saving can be achieved by reducing the uncore frequency to its lowest value. 
+With later kernels, there is now a sysfs entry to allow adjustment of uncore frequency. 
+This manipulates the contest of MSR 0x620, which sets min/max of the uncore for the SKU.
+
+
+API Overview for Uncore
+~~~~~~~~~~~~~~~~~~~~~~~
+* **Uncore Power Init**: Initialise uncore power, populate frequency array and record 
+  original min & max for pkg & die.
+
+* **Uncore Power Exit**: Exit uncore power, restoring original min & max for pkg & die.
+
+* **Get Uncore Power Freq**: Get current uncore freq index for pkg & die.
+
+* **Set Uncore Power Freq**: Set min & max uncore freq index for pkg & die (min and max will be the same).
+
+* **Uncore Power Max**: Set max uncore freq index for pkg & die.
+
+* **Uncore Power Min**: Set min uncore freq index for pkg & die.
+
+* **Get Num Freqs**: Get the number of frequencies in the index array.
+
 References
 ----------
 
diff --git a/lib/power/meson.build b/lib/power/meson.build
index ba8d66074b..80cdeb72d4 100644
--- a/lib/power/meson.build
+++ b/lib/power/meson.build
@@ -21,12 +21,14 @@ sources = files(
         'rte_power.c',
         'rte_power_empty_poll.c',
         'rte_power_pmd_mgmt.c',
+        'rte_power_uncore.c',
 )
 headers = files(
         'rte_power.h',
         'rte_power_empty_poll.h',
         'rte_power_pmd_mgmt.h',
         'rte_power_guest_channel.h',
+        'rte_power_uncore.h',
 )
 if cc.has_argument('-Wno-cast-qual')
     cflags += '-Wno-cast-qual'
diff --git a/lib/power/rte_power_uncore.c b/lib/power/rte_power_uncore.c
new file mode 100644
index 0000000000..5fd8313b03
--- /dev/null
+++ b/lib/power/rte_power_uncore.c
@@ -0,0 +1,401 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright(c) 2022 Intel Corporation
+ */
+
+#include <errno.h>
+
+#include <rte_memcpy.h>
+
+#include "rte_power_uncore.h"
+#include "power_common.h"
+
+#define BUS_FREQ     100000
+
+#define POWER_GOVERNOR_PERF "performance"
+#define POWER_UNCORE_SYSFILE_MAX_FREQ \
+        "/sys/devices/system/cpu/intel_uncore_frequency/package_%02u_die_%02u/max_freq_khz"
+#define POWER_UNCORE_SYSFILE_MIN_FREQ  \
+        "/sys/devices/system/cpu/intel_uncore_frequency/package_%02u_die_%02u/min_freq_khz"
+#define POWER_UNCORE_SYSFILE_BASE_MAX_FREQ \
+        "/sys/devices/system/cpu/intel_uncore_frequency/package_%02u_die_%02u/initial_max_freq_khz"
+#define POWER_UNCORE_SYSFILE_BASE_MIN_FREQ  \
+        "/sys/devices/system/cpu/intel_uncore_frequency/package_%02u_die_%02u/initial_min_freq_khz"
+
+
+struct uncore_power_info {
+    unsigned int die;                    /**< Core die id */
+    unsigned int pkg;                    /**< Package id */
+    uint32_t freqs[RTE_MAX_UNCORE_FREQS];/**< Frequency array */  
+    uint32_t nb_freqs;                   /**< Number of available freqs */
+    FILE *f_cur_min;                     /**< FD of scaling_min */
+    FILE *f_cur_max;                     /**< FD of scaling_max */
+    FILE *f_base_min;                    /**< FD of initial min */
+    FILE *f_base_max;                    /**< FD of initial max */
+    int cur_idx;                         /**< Freq index in freqs array */
+    uint32_t init_max_freq;              /**< Initial max frequency */
+    uint32_t init_min_freq;              /**< Initial min frequency */
+} __rte_cache_aligned;
+
+
+static struct uncore_power_info uncore_info[RTE_MAX_NUMA_NODES][RTE_MAX_NUMA_DIE];
+
+static int
+set_uncore_freq_internal(struct uncore_power_info *ui, uint32_t idx)
+{
+    uint32_t target_uncore_freq, curr_max_freq;
+    int ret;
+
+    if (idx >= RTE_MAX_UNCORE_FREQS || idx >= ui->nb_freqs) {
+        RTE_LOG(ERR, POWER, "Invalid uncore frequency index %u, which "
+                "should be less than %u\n", idx, ui->nb_freqs);
+        return -1;
+    }
+
+    target_uncore_freq = ui->freqs[idx];
+
+    if (fprintf(ui->f_cur_min, "%u", target_uncore_freq) < 0) {
+        RTE_LOG(ERR, POWER, "Fail to write new uncore frequency for "
+                "pkg %02u die %02u\n", ui->pkg, ui->die);
+        return -1;
+    }
+
+    if (fprintf(ui->f_cur_max, "%u", target_uncore_freq) < 0) {
+        RTE_LOG(ERR, POWER, "Fail to write new uncore frequency for "
+                "pkg %02u die %02u\n", ui->pkg, ui->die);
+        return -1;
+    }
+
+    POWER_DEBUG_TRACE("Uncore requency '%u' to be set for pkg %02u die %02u\n",
+                target_uncore_freq, ui->pkg, ui->die);
+    
+    open_core_sysfs_file(&ui->f_cur_max, "rw+", POWER_UNCORE_SYSFILE_MAX_FREQ,
+            ui->pkg, ui->die);
+    if (ui->f_cur_max == NULL) {
+        RTE_LOG(DEBUG, POWER, "failed to open %s\n",
+                POWER_UNCORE_SYSFILE_MAX_FREQ);
+        return -1;
+    }
+    ret = read_core_sysfs_u32(ui->f_cur_max, &curr_max_freq);
+        if (ret < 0) {
+            RTE_LOG(DEBUG, POWER, "Failed to read %s\n",
+                    POWER_UNCORE_SYSFILE_MAX_FREQ);
+            fclose(ui->f_cur_max);
+            return -1;
+        }
+
+    if (target_uncore_freq <= curr_max_freq){
+        fflush(ui->f_cur_min);
+        fflush(ui->f_cur_max);
+    }
+    else {
+        fflush(ui->f_cur_max);
+        fflush(ui->f_cur_min);
+    }
+
+    ui->cur_idx = idx;
+
+    return 0;
+}
+
+/**
+ * Fopen the sys file for the future setting of the uncore die frequency.
+ */
+static int
+power_init_for_setting_uncore_freq(struct uncore_power_info *ui)
+{
+    FILE *f_base_min = NULL, *f_base_max = NULL, *f_min = NULL, *f_max = NULL;
+    uint32_t base_min_freq, base_max_freq, min_freq, max_freq;
+    int ret;
+
+    /* open and read all uncore sys files */
+    /* Base_max */
+    open_core_sysfs_file(&f_base_max, "r", POWER_UNCORE_SYSFILE_BASE_MAX_FREQ,
+            ui->pkg, ui->die);
+    if (f_base_max == NULL) {
+        RTE_LOG(DEBUG, POWER, "failed to open %s\n",
+                POWER_UNCORE_SYSFILE_BASE_MAX_FREQ);
+        goto err;
+    }
+    ret = read_core_sysfs_u32(f_base_max, &base_max_freq);
+    if (ret < 0) {
+        RTE_LOG(DEBUG, POWER, "Failed to read %s\n",
+                POWER_UNCORE_SYSFILE_BASE_MAX_FREQ);
+        goto err;
+    }
+
+    /* Base min */
+    open_core_sysfs_file(&f_base_min, "r", POWER_UNCORE_SYSFILE_BASE_MIN_FREQ,
+        ui->pkg, ui->die);
+    if (f_base_min == NULL) {
+        RTE_LOG(DEBUG, POWER, "failed to open %s\n",
+                POWER_UNCORE_SYSFILE_BASE_MIN_FREQ);
+        goto err;
+    }
+    if (f_base_min != NULL) {
+        ret = read_core_sysfs_u32(f_base_min, &base_min_freq);
+        if (ret < 0) {
+            RTE_LOG(DEBUG, POWER, "Failed to read %s\n",
+                    POWER_UNCORE_SYSFILE_BASE_MIN_FREQ);
+            goto err;
+        }
+    }
+
+    /* Curr min */
+    open_core_sysfs_file(&f_min, "rw+", POWER_UNCORE_SYSFILE_MIN_FREQ,
+            ui->pkg, ui->die);
+    if (f_min == NULL) {
+        RTE_LOG(DEBUG, POWER, "failed to open %s\n",
+                POWER_UNCORE_SYSFILE_MIN_FREQ);
+        goto err;
+    }
+    if (f_min != NULL) {
+        ret = read_core_sysfs_u32(f_min, &min_freq);
+        if (ret < 0) {
+            RTE_LOG(DEBUG, POWER, "Failed to read %s\n",
+                    POWER_UNCORE_SYSFILE_MIN_FREQ);
+            goto err;
+        }
+    }
+
+    /* Curr max */
+    open_core_sysfs_file(&f_max, "rw+", POWER_UNCORE_SYSFILE_MAX_FREQ,
+            ui->pkg, ui->die);
+    if (f_max == NULL) {
+        RTE_LOG(DEBUG, POWER, "failed to open %s\n",
+                POWER_UNCORE_SYSFILE_MAX_FREQ);
+        goto err;
+    }
+    if (f_max != NULL) {
+        ret = read_core_sysfs_u32(f_max, &max_freq);
+        if (ret < 0) {
+            RTE_LOG(DEBUG, POWER, "Failed to read %s\n",
+                    POWER_UNCORE_SYSFILE_MAX_FREQ);
+            goto err;
+        }
+    }	
+
+    /* assign file handles */
+    ui->f_cur_min = f_min;
+    ui->f_cur_max = f_max;
+    ui->f_base_max = f_base_max;
+    ui->f_base_min = f_base_min;
+    ui->init_max_freq = base_max_freq;
+    ui->init_min_freq = base_min_freq;
+
+    return 0;
+
+err:
+    if (f_base_min != NULL)
+        fclose(f_base_min);
+    if (f_base_max != NULL)
+        fclose(f_base_max);
+    if (f_min != NULL)
+        fclose(f_min);
+    if (f_max != NULL)
+        fclose(f_max);
+    return -1;
+}
+
+/**
+ * Get the available uncore frequencies of the specific die by reading the
+ * sys file.
+ */
+static int
+power_get_available_uncore_freqs(struct uncore_power_info *ui)
+{
+    int ret = -1;
+    uint32_t i, num_uncore_freqs = 0;
+
+    num_uncore_freqs = (ui->init_max_freq - ui->init_min_freq) / BUS_FREQ +1;
+    if (num_uncore_freqs >= RTE_MAX_UNCORE_FREQS) {
+        RTE_LOG(ERR, POWER, "Too many available uncore frequencies: %d\n",
+                num_uncore_freqs);
+        goto out;
+    }
+
+    /* Generate the uncore freq bucket array. */
+    for (i = 0; i < num_uncore_freqs; i++) {
+        ui->freqs[i] = ui->init_max_freq - (i) * BUS_FREQ;
+    }
+
+    ui->nb_freqs = num_uncore_freqs;
+
+    ret = 0;
+
+    POWER_DEBUG_TRACE("%d uncore frequency(s) of pkg %02u die %02u are available\n",
+            num_uncore_freqs, ui->pkg, ui->die);
+
+out:
+    return ret;
+}
+
+
+int
+rte_power_uncore_init(unsigned int pkg, unsigned int die)
+{
+    struct uncore_power_info *ui;
+
+    /* Check if pkg and die values are viable */
+    if (pkg >= RTE_MAX_NUMA_NODES) {
+        RTE_LOG(DEBUG, POWER, "Package number %02u can not exceed %u\n",
+                pkg, RTE_MAX_NUMA_NODES - 1U);
+        return -1;
+    }
+
+    if (die >= RTE_MAX_NUMA_DIE) {
+        RTE_LOG(DEBUG, POWER, "Die number %02u can not exceed %u\n",
+                die, RTE_MAX_NUMA_DIE - 1U);
+        return -1;
+    }
+
+    ui = &uncore_info[pkg][die];
+    ui->die = die;
+    ui->pkg = pkg;
+    
+    /* Init for setting unocre die frequency */
+    if (power_init_for_setting_uncore_freq(ui) < 0) {
+        RTE_LOG(DEBUG, POWER, "Cannot init for setting uncore frequency for "
+                "pkg %02u die %02u\n", pkg, die);
+        return -1;
+    }
+
+    /* Get the available frequencies */
+    if (power_get_available_uncore_freqs(ui) < 0) {
+        RTE_LOG(DEBUG, POWER, "Cannot get available uncore frequencies of "
+                "pkg %02u die %02u\n", pkg, die);
+        return -1;
+    }
+
+    return 0;
+}
+
+int
+rte_power_uncore_exit(unsigned int pkg, unsigned int die)
+{
+    struct uncore_power_info *ui;
+
+    if (pkg >= RTE_MAX_NUMA_NODES) {
+        RTE_LOG(DEBUG, POWER, "Package number %02u can not exceed %u\n",
+                pkg, RTE_MAX_NUMA_NODES - 1U);
+        return -1;
+    }
+
+    if (die >= RTE_MAX_NUMA_DIE) {
+        RTE_LOG(DEBUG, POWER, "Die number %02u can not exceed %u\n",
+                die, RTE_MAX_NUMA_DIE - 1U);
+        return -1;
+    }
+
+    ui = &uncore_info[pkg][die];
+
+    /* Close FD of setting freq */
+    fclose(ui->f_cur_min);
+    fclose(ui->f_cur_max);
+    fclose(ui->f_base_max);
+    fclose(ui->f_base_min);
+    ui->f_cur_min = NULL;
+    ui->f_cur_max = NULL;
+    ui->f_base_min = NULL;
+    ui->f_base_max = NULL;
+
+    return 0;
+}
+
+int
+rte_power_get_uncore_freq(unsigned int pkg, unsigned int die)
+{
+    if (pkg >= RTE_MAX_NUMA_NODES) {
+        RTE_LOG(DEBUG, POWER, "Invalid package number\n");
+        return -1;
+    }
+
+    if (die >= RTE_MAX_NUMA_DIE) {
+        RTE_LOG(DEBUG, POWER, "Invalid die number\n");
+        return -1;
+    }
+
+    return uncore_info[pkg][die].cur_idx;
+}
+
+int
+rte_power_set_uncore_freq(unsigned int pkg, unsigned int die, uint32_t index)
+{
+    if (pkg >= RTE_MAX_NUMA_NODES) {
+        RTE_LOG(DEBUG, POWER, "Invalid package number\n");
+        return -1;
+    }
+
+    if (die >= RTE_MAX_NUMA_DIE) {
+        RTE_LOG(DEBUG, POWER, "Invalid die number\n");
+        return -1;
+    }
+
+    return set_uncore_freq_internal(&(uncore_info[pkg][die]), index);
+}
+
+int
+rte_power_uncore_freq_max(unsigned int pkg, unsigned int die)
+{
+    if (pkg >= RTE_MAX_NUMA_NODES) {
+        RTE_LOG(DEBUG, POWER, "Invalid package number\n");
+        return -1;
+    }
+
+    if (die >= RTE_MAX_NUMA_DIE) {
+        RTE_LOG(DEBUG, POWER, "Invalid die number\n");
+        return -1;
+    }
+
+    struct uncore_power_info *ui = &uncore_info[pkg][die];
+
+    if (fprintf(ui->f_cur_max, "%u", 0) < 0) {
+        RTE_LOG(ERR, POWER, "Fail to write new uncore frequency for "
+                "pkg %02u die %02u\n", ui->pkg, ui->die);
+        return -1;
+    }
+
+    fflush(ui->f_cur_max);
+    return 0;
+}
+
+
+int
+rte_power_uncore_freq_min(unsigned int pkg, unsigned int die)
+{
+    if (pkg >= RTE_MAX_NUMA_NODES) {
+        RTE_LOG(DEBUG, POWER, "Invalid package number\n");
+        return -1;
+    }
+
+    if (die >= RTE_MAX_NUMA_DIE) {
+        RTE_LOG(DEBUG, POWER, "Invalid die number\n");
+        return -1;
+    }
+
+    struct uncore_power_info *ui = &uncore_info[pkg][die];
+
+    if (fprintf(ui->f_cur_min, "%u",  ui->freqs[ui->nb_freqs - 1]) < 0) {
+        RTE_LOG(ERR, POWER, "Fail to write new uncore frequency for "
+                "pkg %02u die %02u\n", ui->pkg, ui->die);
+        return -1;
+    }
+
+    fflush(ui->f_cur_min);
+    return 0;
+}
+
+int
+rte_power_uncore_get_num_freqs(unsigned int pkg, unsigned int die)
+{
+    if (pkg >= RTE_MAX_NUMA_NODES) {
+        RTE_LOG(DEBUG, POWER, "Invalid package number\n");
+        return -1;
+    }
+
+    if (die >= RTE_MAX_NUMA_DIE) {
+        RTE_LOG(DEBUG, POWER, "Invalid die number\n");
+        return -1;
+    }
+
+    return uncore_info[pkg][die].nb_freqs;
+}
diff --git a/lib/power/rte_power_uncore.h b/lib/power/rte_power_uncore.h
new file mode 100644
index 0000000000..9a8917ed8b
--- /dev/null
+++ b/lib/power/rte_power_uncore.h
@@ -0,0 +1,151 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright(c) 2022 Intel Corporation
+ */
+
+#ifndef _RTE_POWER_UNCORE_H
+#define _RTE_POWER_UNCORE_H
+
+/**
+ * @file
+ * RTE Uncore Frequency Management
+ */
+
+#include "rte_power.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * Initialize uncore frequency managment for specific die on a package. It will check and set the
+ * governor to performance for the die, get the available frequencies, and
+ * prepare to set new die frequency.
+ * 
+ * This function should NOT be called in the fast path.
+ *
+ * @param pkg
+ *  Package number.
+ * @param die
+ *  Die number.
+ *
+ * @return
+ *  - 0 on success.
+ *  - Negative on error.
+ */
+__rte_experimental
+int
+rte_power_uncore_init(unsigned int pkg, unsigned int die);
+
+/**
+ * Exit uncore frequency management on a specific die on a package. It will set the governor to which
+ * is before initialized.
+ * 
+ * This function should NOT be called in the fast path.
+ *
+ * @param pkg
+ *  Package number.
+ * @param die
+ *  Die number.
+ *
+ * @return
+ *  - 0 on success.
+ *  - Negative on error.
+ */
+__rte_experimental
+int
+rte_power_uncore_exit(unsigned int pkg, unsigned int die);
+
+/**
+ * Return the current index of available frequencies of a specific die on a package.
+ * It should be protected outside of this function for threadsafe.
+ * 
+ * This function should NOT be called in the fast path.
+ *
+ * @param pkg
+ *  Package number.
+ * @param die
+ *  Die number.
+ *
+ * @return
+ *  - The current index of available frequencies.
+ *  - Negative on error.
+ */
+__rte_experimental
+int
+rte_power_get_uncore_freq(unsigned int pkg, unsigned int die);
+
+/**
+ * Set the new frequency for a specific die on a package by indicating the index of
+ * available frequencies.
+ * It should be protected outside of this function for threadsafe.
+ * 
+ * This function should NOT be called in the fast path.
+ *
+ * @param pkg
+ *  Package number.
+ * @param die
+ *  Die number.
+ * @param index
+ *  The index of available frequencies.
+ *
+ * @return
+ *  - 0 on success.
+ *  - Negative on error.
+ */
+__rte_experimental
+int
+rte_power_set_uncore_freq(unsigned int pkg, unsigned int die, uint32_t index);
+
+/**
+ * Scale up the frequency of a specific die on a package to the highest according to the
+ * available frequencies.
+ * It should be protected outside of this function for threadsafe.
+ * 
+ * This function should NOT be called in the fast path.
+ *
+ * @param pkg
+ *  Package number.
+ * @param die
+ *  Die number.
+ *
+ * @return
+ *  - 0 on success.
+ *  - Negative on error.
+ */
+__rte_experimental
+int
+rte_power_uncore_freq_max(unsigned int pkg, unsigned int die);
+
+/**
+ * Scale down the frequency of a specific die on a package to the lowest according to the
+ * available frequencies.
+ * It should be protected outside of this function for threadsafe.
+ * 
+ * This function should NOT be called in the fast path.
+ *
+ * @param pkg
+ *  Package number.
+ * @param die
+ *  Die number.  
+ *
+ * @return
+ *  - 0 on success.
+ *  - Negative on error.
+ */
+__rte_experimental
+int
+rte_power_uncore_freq_min(unsigned int pkg, unsigned int die);
+
+/**
+ * Return the list length of available frequencies in the index array
+ * 
+ * @param pkg
+ *  Package number.
+ * @param die
+ *  Die number. 
+ * 
+ * @return
+ *  - The number of available index's in frequency array
+ *  - Negative on error
+ */
+__rte_experimental
+int
+rte_power_uncore_get_num_freqs(unsigned int pkg, unsigned int die);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
diff --git a/lib/power/version.map b/lib/power/version.map
index a687754f4a..e9681df291 100644
--- a/lib/power/version.map
+++ b/lib/power/version.map
@@ -48,4 +48,11 @@ EXPERIMENTAL {
 	rte_power_pmd_mgmt_set_pause_duration;
 	rte_power_pmd_mgmt_set_scaling_freq_max;
 	rte_power_pmd_mgmt_set_scaling_freq_min;
+	rte_power_uncore_init;
+	rte_power_uncore_exit;
+	rte_power_get_uncore_freq;
+	rte_power_set_uncore_freq;
+	rte_power_uncore_freq_max;
+	rte_power_uncore_freq_min;
+	rte_power_uncore_get_num_freqs;
 };
-- 
2.25.1

[PATCH v1 2/4] l3fwd-power: add option to call uncore api

[tadhgkearney]

Add option for setting uncore frequency min/max/index, through uncore api.
This will be set for each package and die on the SKU. On exit, uncore frequency will be reverted back to previous frequency.

Signed-off-by: tadhgkearney <tadhg.kearney@intel.com>
---
 .../sample_app_ug/l3_forward_power_man.rst    |  28 ++++
 examples/l3fwd-power/main.c                   | 154 +++++++++++++++++-
 2 files changed, 181 insertions(+), 1 deletion(-)

diff --git a/doc/guides/sample_app_ug/l3_forward_power_man.rst b/doc/guides/sample_app_ug/l3_forward_power_man.rst
index 8f6d906200..7b9d99ef54 100644
--- a/doc/guides/sample_app_ug/l3_forward_power_man.rst
+++ b/doc/guides/sample_app_ug/l3_forward_power_man.rst
@@ -97,6 +97,12 @@ where,
 *   -P: Sets all ports to promiscuous mode so that packets are accepted regardless of the packet's Ethernet MAC destination address.
     Without this option, only packets with the Ethernet MAC destination address set to the Ethernet address of the port are accepted.
 
+*   -u: optional, sets uncore frequency to minimum value.
+
+*   -U: optional, sets uncore frequency to maximum value.
+
+*   -i (frequency index): optional, sets uncore frequency to frequency index value, by setting min and max values to be the same.
+
 *   --config (port,queue,lcore)[,(port,queue,lcore)]: determines which queues from which ports are mapped to which cores.
 
 *   --max-pkt-len: optional, maximum packet length in decimal (64-9600)
@@ -364,3 +370,25 @@ in the DPDK Programmer's Guide for more details on PMD power management.
 .. code-block:: console
 
         ./<build_dir>/examples/dpdk-l3fwd-power -l 1-3 -- -p 0x0f --config="(0,0,2),(0,1,3)" --pmd-mgmt=scale
+
+Setting Uncore Values
+---------------------
+
+Uncore frequency can be adjusted through manipulating related sysfs entries to adjust the minimum and maximum uncore values. 
+This will be set for each package and die on the SKU. Three options are available for setting uncore frequency:
+
+``-u``
+  This will set uncore to minimum frequency possible.
+
+``-U``
+  This will set uncore to maximum frequency possible.
+
+``-i``
+  This will allow you to set the specific uncore frequency index that you want, by setting
+  minimum and maximum values to be the same. Frequency index's are set 100000Hz apart from 
+  maximum to minimum.
+  Frequency index values are in decending order, ie, index 0 is maximum frequency index.
+
+.. code-block:: console
+
+        ./<build_dir>/examples/dpdk-l3fwd-power -l 1-3 -- -p 0x0f --config="(0,0,2),(0,1,3)" -i 1
diff --git a/examples/l3fwd-power/main.c b/examples/l3fwd-power/main.c
index 887c6eae3f..98a2e8428a 100644
--- a/examples/l3fwd-power/main.c
+++ b/examples/l3fwd-power/main.c
@@ -15,6 +15,8 @@
 #include <unistd.h>
 #include <signal.h>
 #include <math.h>
+#include <dirent.h>
+#include <fnmatch.h>
 
 #include <rte_common.h>
 #include <rte_byteorder.h>
@@ -47,6 +49,7 @@
 #include <rte_metrics.h>
 #include <rte_telemetry.h>
 #include <rte_power_pmd_mgmt.h>
+#include <rte_power_uncore.h>
 
 #include "perf_core.h"
 #include "main.h"
@@ -71,6 +74,7 @@
 
 #ifndef APP_LOOKUP_METHOD
 #define APP_LOOKUP_METHOD             APP_LOOKUP_LPM
+
 #endif
 
 #if (APP_LOOKUP_METHOD == APP_LOOKUP_EXACT_MATCH)
@@ -134,9 +138,14 @@
 
 #define NUM_TELSTATS RTE_DIM(telstats_strings)
 
+#define UNCORE_FREQUENCY_DIR "/sys/devices/system/cpu/intel_uncore_frequency"
+
 static uint16_t nb_rxd = RTE_TEST_RX_DESC_DEFAULT;
 static uint16_t nb_txd = RTE_TEST_TX_DESC_DEFAULT;
 
+/* Max number of nodes times dies available on uncore */
+#define MAX_DIE_NODES (RTE_MAX_NUMA_DIE * RTE_MAX_NUMA_NODES)
+
 /* ethernet addresses of ports */
 static struct rte_ether_addr ports_eth_addr[RTE_MAX_ETHPORTS];
 
@@ -145,6 +154,8 @@ static rte_spinlock_t locks[RTE_MAX_ETHPORTS];
 
 /* mask of enabled ports */
 static uint32_t enabled_port_mask = 0;
+/* if uncore frequency was enabled without errors */
+static int enabled_uncore = 0;
 /* Ports set in promiscuous mode off by default. */
 static int promiscuous_on = 0;
 /* NUMA is enabled by default. */
@@ -165,6 +176,13 @@ struct telstats_name {
 	char name[RTE_ETH_XSTATS_NAME_SIZE];
 };
 
+struct uncore_info{
+	unsigned int pkg;
+	unsigned int die;
+};
+
+struct uncore_info ui[MAX_DIE_NODES];
+
 /* telemetry stats to be reported */
 const struct telstats_name telstats_strings[] = {
 	{"empty_poll"},
@@ -1616,6 +1634,9 @@ print_usage(const char *prgname)
 		"  [--max-pkt-len PKTLEN]\n"
 		"  -p PORTMASK: hexadecimal bitmask of ports to configure\n"
 		"  -P: enable promiscuous mode\n"
+		"  -u: set min frequency for uncore\n"
+		"  -U: set max frequency for uncore\n"
+		"  -i (frequency index): set frequency index for uncore\n"
 		"  --config (port,queue,lcore): rx queues configuration\n"
 		"  --high-perf-cores CORELIST: list of high performance cores\n"
 		"  --perf-config: similar as config, cores specified as indices"
@@ -1672,6 +1693,106 @@ static int parse_max_pkt_len(const char *pktlen)
 	return len;
 }
 
+static int
+parse_uncore_dir(void)
+{
+	DIR *d;
+	struct dirent *dir;
+	char pkg[3], die[3];
+	unsigned int count = 0;
+	const char filter[] = "*freq_khz*";
+	
+	d = opendir(UNCORE_FREQUENCY_DIR);
+ 	if (!d) {
+ 		RTE_LOG(ERR, EAL, "Unable to open uncore frequency directory");
+		return -1;
+	}
+
+	else {
+		/* Loop through every file name in uncore frequency dir extracting pkg + die numbers from file names */
+    	while ((dir = readdir(d)) != NULL) {
+			if (fnmatch(filter, dir->d_name, 0) > 0) {
+				/* Extract pkg + die numbers from string 'package_XX_die_XX' */
+				sprintf(pkg, "%c%c", dir->d_name[8], dir->d_name[9]);
+				sprintf(die, "%c%c", dir->d_name[15], dir->d_name[16]);
+				ui[count].pkg = atoi(pkg);
+				ui[count].die = atoi(die);
+				count++;
+			}
+    	}
+    	closedir(d);
+  	}
+  	return(count);
+}
+
+static int
+parse_uncore_min_max(const char *choice)
+{
+	int ret = 0, total_files, i;
+	unsigned int die, pkg;
+	total_files = parse_uncore_dir();
+
+	if (total_files < 1)
+		return -1;
+
+	for (i = 0; i < total_files; i++){
+		die = ui[i].die;
+		pkg = ui[i].pkg;
+		rte_power_uncore_init(pkg, die);
+		if (!strncmp(choice, "max", 3)){
+			ret = rte_power_uncore_freq_max(pkg, die);
+			if (ret == -1)
+				RTE_LOG(INFO, L3FWD_POWER, "Unable to set max uncore value for pkg %02u die %02u\n", pkg, die);
+		}
+
+		else if (!strncmp(choice, "min", 3)){
+			ret = rte_power_uncore_freq_min(pkg, die);
+			if (ret == -1){
+				RTE_LOG(INFO, L3FWD_POWER, "Unable to set min uncore value for pkg %02u die %02u\n", pkg, die);
+				return ret;
+			}
+		}
+		else {
+			RTE_LOG(INFO, L3FWD_POWER, "Uncore choice provided invalid\n");
+			return -1;
+		}		
+	}
+
+	RTE_LOG(INFO, L3FWD_POWER, "Successfully set max/min uncore frequency.\n");
+	return ret;
+}
+
+static int
+parse_uncore_index(const char *choice)
+{
+	int ret = 0, total_files, i;
+	unsigned int  die, pkg;
+	total_files = parse_uncore_dir();
+
+	if (total_files < 1)
+		return -1;
+
+	for (i = 0; i < total_files; i++){
+		die = ui[i].die;
+		pkg = ui[i].pkg;
+		rte_power_uncore_init(pkg, die);
+
+		int frequency_index= atoi(choice);
+		int freq_array_len = rte_power_uncore_get_num_freqs(pkg, die);
+		if (frequency_index > freq_array_len){
+			RTE_LOG(INFO, L3FWD_POWER, "Frequency index given out of range, please choose a value from 0 to %d.\n", freq_array_len);
+			return -1;
+		}
+		ret = rte_power_set_uncore_freq(pkg, die, frequency_index);
+		if (ret == -1){
+			RTE_LOG(INFO, L3FWD_POWER, "Unable to set uncore index value for pkg %02u die %02u\n", pkg, die);
+			return ret;
+		}
+	}
+	RTE_LOG(INFO, L3FWD_POWER, "Successfully set freq index for uncore\n");	
+	return ret;
+}
+
 static int
 parse_portmask(const char *portmask)
 {
@@ -1864,7 +1985,7 @@ parse_args(int argc, char **argv)
 
 	argvopt = argv;
 
-	while ((opt = getopt_long(argc, argvopt, "p:l:m:h:P",
+	while ((opt = getopt_long(argc, argvopt, "p:l:m:h:P:u U i:",
 				lgopts, &option_index)) != EOF) {
 
 		switch (opt) {
@@ -1893,6 +2014,32 @@ parse_args(int argc, char **argv)
 			limit = parse_max_pkt_len(optarg);
 			freq_tlb[HGH] = limit;
 			break;
+		case 'u': ;
+			const char* min = "min";
+			enabled_uncore = parse_uncore_min_max(min);
+			if (enabled_uncore < 0) {
+				printf("Unable to reach min uncore value\n");
+				print_usage(prgname);
+				return -1;
+			}
+			break;
+		case 'U': ;
+			const char* max = "max";
+			enabled_uncore = parse_uncore_min_max(max);
+			if (enabled_uncore < 0) {
+				printf("Unable to reach max uncore value\n");
+				print_usage(prgname);
+				return -1;
+			}
+			break;
+		case 'i':
+			enabled_uncore = parse_uncore_index(optarg);
+			if (enabled_uncore < 0) {
+				printf("Unable to reach uncore index value\n");
+				print_usage(prgname);
+				return -1;
+			}
+			break;
 		/* long options */
 		case 0:
 			if (!strncmp(lgopts[option_index].name, "config", 6)) {
@@ -2365,6 +2512,8 @@ static int
 deinit_power_library(void)
 {
 	unsigned int lcore_id;
+	int i, total_files;
+	total_files = parse_uncore_dir();
 	int ret = 0;
 
 	RTE_LCORE_FOREACH(lcore_id) {
@@ -2377,6 +2526,9 @@ deinit_power_library(void)
 			return ret;
 		}
 	}
+
+	for (i = 0; i < total_files; i++)
+		rte_power_uncore_exit(ui[i].pkg, ui[i].die);
 	return ret;
 }
 
-- 
2.25.1

[PATCH v1 3/4] test/power: add unit tests for uncore api

[tadhgkearney]

Add basic unit tests covering all seven uncore api's.

Signed-off-by: tadhgkearney <tadhg.kearney@intel.com>
---
 app/test/meson.build         |   2 +
 app/test/test_power_uncore.c | 245 +++++++++++++++++++++++++++++++++++
 2 files changed, 247 insertions(+)
 create mode 100644 app/test/test_power_uncore.c

diff --git a/app/test/meson.build b/app/test/meson.build
index 431c5bd318..3ab360ecee 100644
--- a/app/test/meson.build
+++ b/app/test/meson.build
@@ -100,6 +100,7 @@ test_sources = files(
         'test_power.c',
         'test_power_cpufreq.c',
         'test_power_kvm_vm.c',
+        'test_power_uncore.c',
         'test_prefetch.c',
         'test_rand_perf.c',
         'test_rawdev.c',
@@ -240,6 +241,7 @@ fast_tests = [
         ['power_cpufreq_autotest', false, true],
         ['power_autotest', true, true],
         ['power_kvm_vm_autotest', false, true],
+        ['power_uncore_autotest', true, true],
         ['reorder_autotest', true, true],
         ['service_autotest', true, true],
         ['thash_autotest', true, true],
diff --git a/app/test/test_power_uncore.c b/app/test/test_power_uncore.c
new file mode 100644
index 0000000000..80d1ae4025
--- /dev/null
+++ b/app/test/test_power_uncore.c
@@ -0,0 +1,245 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright(c) 2010-2022 Intel Corporation
+ */
+
+#include "test.h"
+
+#ifndef RTE_LIB_POWER
+
+static int
+test_power_uncore(void)
+{
+    printf("Power management library not supported, skipping test\n");
+    return TEST_SKIPPED;
+}
+
+#else
+#include <rte_power_uncore.h>
+#include <power_common.h>
+
+#define VALID_PKG 0
+#define VALID_DIE 0
+#define INVALID_PKG (RTE_MAX_NUMA_NODES + 1)
+#define INVALID_DIE (RTE_MAX_NUMA_DIE + 1)
+#define VALID_INDEX 1
+#define INVALID_INDEX (RTE_MAX_UNCORE_FREQS + 1)
+
+static int check_power_uncore_init(void)
+{
+    int ret;
+
+    /* Test initialisation of uncore configuration*/
+    ret = rte_power_uncore_init(VALID_PKG, VALID_DIE);
+    if(ret < 0){
+        printf("Cannot initialise uncore power management for pkg %u die %u, this "
+            "may occur if environment is not configured "
+            "correctly(APCI cpufreq) or operating in another valid "
+            "Power management environment\n", VALID_PKG, VALID_DIE);
+        return -1;
+    }
+
+    /* Unsuccessful Test */
+    ret = rte_power_uncore_init(INVALID_PKG, INVALID_DIE);
+    if (ret == 0) {
+        printf("Unexpectedly was able to initialise uncore power managment "
+            "for pkg %u die %u\n", INVALID_PKG, INVALID_DIE);
+        return -1;
+    }
+
+    return 0;
+}
+
+static int
+check_power_get_uncore_freq(void)
+{
+    int ret;
+
+    /* Successfully get uncore freq */
+    ret = rte_power_get_uncore_freq(VALID_PKG, VALID_DIE);
+    if (ret < 0) {
+        printf("Failed to get uncore frequency for pkg %u die %u\n",
+                            VALID_PKG, VALID_DIE);
+        return -1;
+    }
+
+    /* Unsuccessful Test */
+    ret = rte_power_get_uncore_freq(INVALID_PKG, INVALID_DIE);
+    if (ret >= 0) {
+        printf("Unexpectedly got invalid uncore frequency for pkg %u die %u\n",
+                            INVALID_PKG, INVALID_DIE);
+        return -1;
+    }
+
+    return 0;
+}
+
+static int
+check_power_set_uncore_freq(void)
+{
+    int ret;
+
+    /* Successfully set uncore freq */
+    ret = rte_power_set_uncore_freq(VALID_PKG, VALID_DIE, VALID_INDEX);
+    if (ret < 0) {
+        printf("Failed to set uncore frequency for pkg %u die %u index %u\n",
+                            VALID_PKG, VALID_DIE, VALID_INDEX);
+        return -1;
+    }
+
+    /* Try to unsuccesfully set invlaid uncore freq index */
+    ret = rte_power_set_uncore_freq(VALID_PKG, VALID_DIE, INVALID_INDEX);
+    if (ret == 0) {
+        printf("Unexpectedly set invalid uncore index for pkg %u die %u index %u\n",
+                            VALID_PKG, VALID_DIE, INVALID_INDEX);
+        return -1;
+    }
+
+    /* Unsuccessful Test */
+    ret = rte_power_set_uncore_freq(INVALID_PKG, INVALID_DIE, VALID_INDEX);
+    if (ret == 0) {
+        printf("Unexpectedly set invalid uncore frequency for pkg %u die %u index %u\n",
+                            INVALID_PKG, INVALID_DIE, VALID_INDEX);
+        return -1;
+    }
+
+    return 0;
+}
+
+static int
+check_power_uncore_freq_max(void)
+{
+    int ret;
+
+    /* Successfully get max uncore freq */
+    ret = rte_power_uncore_freq_max(VALID_PKG, VALID_DIE);
+    if (ret < 0) {
+        printf("Failed to set max uncore frequency for pkg %u die %u\n",
+                            VALID_PKG, VALID_DIE);
+        return -1;
+    }
+
+    /* Unsuccessful Test */
+    ret = rte_power_uncore_freq_max(INVALID_PKG, INVALID_DIE);
+    if (ret == 0) {
+        printf("Unexpectedly set invalid max uncore frequency for pkg %u die %u\n",
+                            INVALID_PKG, INVALID_DIE);
+        return -1;
+    }
+
+    return 0;
+}
+
+static int
+check_power_uncore_freq_min(void)
+{
+    int ret;
+
+    /* Successfully get min uncore freq */
+    ret = rte_power_uncore_freq_min(VALID_PKG, VALID_DIE);
+    if (ret < 0) {
+        printf("Failed to set min uncore frequency for pkg %u die %u\n",
+                            VALID_PKG, VALID_DIE);
+        return -1;
+    }
+
+    /* Unsuccessful Test */
+    ret = rte_power_uncore_freq_min(INVALID_PKG, INVALID_DIE);
+    if (ret == 0) {
+        printf("Unexpectedly set invalid min uncore frequency for pkg %u die %u\n",
+                            INVALID_PKG, INVALID_DIE);
+        return -1;
+    }
+
+    return 0;
+}
+
+static int
+check_power_uncore_get_num_freqs(void)
+{
+    int ret;
+
+    /* Successfully get number of uncore freq */
+    ret = rte_power_uncore_get_num_freqs(VALID_PKG, VALID_DIE);
+    if (ret < 0) {
+        printf("Failed to get number of uncore frequencies for pkg %u die %u\n",
+                            VALID_PKG, VALID_DIE);
+        return -1;
+    }
+
+    /* Unsuccessful Test */
+    ret = rte_power_uncore_get_num_freqs(INVALID_PKG, INVALID_DIE);
+    if (ret >= 0) {
+        printf("Unexpectedly got number of invalid frequencies for pkg %u die %u\n",
+                            INVALID_PKG, INVALID_DIE);
+        return -1;
+    }
+
+    return 0;
+}
+
+static int
+check_power_uncore_exit(void)
+{
+    int ret;
+
+    /* Successfully exit uncore power management */
+    ret = rte_power_uncore_exit(VALID_PKG, VALID_DIE);
+    if(ret < 0) {
+        printf("Failed to exit uncore power management for pkg %u die %u\n",
+                            VALID_PKG, VALID_DIE);
+        return -1;
+    }
+
+    /* Unsuccessful Test */
+    ret = rte_power_uncore_exit(INVALID_PKG, INVALID_DIE);
+    if (ret == 0) {
+        printf("Unexpectedly was able to exit uncore power management for pkg %u die %u\n",
+                            INVALID_PKG, INVALID_DIE);
+        return -1;
+    }
+
+    return 0;
+}
+
+static int
+test_power_uncore(void)
+{
+    int ret;
+
+    ret = check_power_uncore_init();
+    if (ret < 0)
+        goto fail_all;
+    
+    ret = check_power_get_uncore_freq();
+    if (ret < 0)
+        goto fail_all;
+
+    ret = check_power_set_uncore_freq();
+    if (ret < 0)
+        goto fail_all;
+
+    ret = check_power_uncore_freq_max();
+    if (ret < 0)
+        goto fail_all;
+
+    ret = check_power_uncore_freq_min();
+    if (ret < 0)
+        goto fail_all;
+
+    ret = check_power_uncore_get_num_freqs();
+    if (ret < 0)
+        goto fail_all;
+    
+    ret = check_power_uncore_exit();
+    if (ret < 0)
+        return -1;
+
+    return 0;
+
+fail_all:
+    rte_power_uncore_exit(VALID_PKG, VALID_DIE);
+    return -1;
+}
+#endif
+
+REGISTER_TEST_COMMAND(power_uncore_autotest, test_power_uncore);
-- 
2.25.1

[PATCH v1 4/4] config: add uncore defines for x86

[tadhgkearney]

Add global define for max numa die and max uncore freqs.

Signed-off-by: tadhgkearney <tadhg.kearney@intel.com>
---
 config/x86/meson.build | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/config/x86/meson.build b/config/x86/meson.build
index 54345c4da3..f81103d8e3 100644
--- a/config/x86/meson.build
+++ b/config/x86/meson.build
@@ -73,3 +73,5 @@ endif
 dpdk_conf.set('RTE_CACHE_LINE_SIZE', 64)
 dpdk_conf.set('RTE_MAX_LCORE', 128)
 dpdk_conf.set('RTE_MAX_NUMA_NODES', 32)
+dpdk_conf.set('RTE_MAX_NUMA_DIE', 1)
+dpdk_conf.set('RTE_MAX_UNCORE_FREQS', 32)
-- 
2.25.1

Re: [PATCH v1 1/4] power: add uncore api to power library

[Stephen Hemminger]

On Mon, 11 Jul 2022 16:22:57 +0000
tadhgkearney <tadhg.kearney@intel.com> wrote:

> +    FILE *f_cur_min;                     /**< FD of scaling_min */
> +    FILE *f_cur_max;                     /**< FD of scaling_max */
> +    FILE *f_base_min;                    /**< FD of initial min */
> +    FILE *f_base_max;                    /**< FD of initial max */

Do you need to hold these extra FD's open?
Also wasteful to use stdio for simple control sysfs like this.

RE: [PATCH v1 0/4] add uncore api to be called through l3fwd-power

[Pattan, Reshma]

> -----Original Message-----
> From: Kearney, Tadhg <tadhg.kearney@intel.com>
> Sent: Monday, July 11, 2022 5:23 PM
> To: dev@dpdk.org
> Cc: dave.hunt@intel.com; Burakov, Anatoly <anatoly.burakov@intel.com>;
> Pattan, Reshma <reshma.pattan@intel.com>; Kearney, Tadhg
> <tadhg.kearney@intel.com>
> Subject: [PATCH v1 0/4] add uncore api to be called through l3fwd-power
> 

The below patch  should be the 1st patch in the series. As the macros in this patch are used by rest of the patches in the series.

[PATCH v1 4/4] config: add uncore defines for x86 

Thanks,
Reshma

RE: [PATCH v1 1/4] power: add uncore api to power library

[Kearney, Tadhg]

> -----Original Message-----
> From: Stephen Hemminger <stephen@networkplumber.org>
> Sent: Monday 11 July 2022 17:37
> To: Kearney, Tadhg <tadhg.kearney@intel.com>
> Cc: dev@dpdk.org; dave.hunt@intel.com; Burakov, Anatoly
> <anatoly.burakov@intel.com>; Pattan, Reshma <reshma.pattan@intel.com>
> Subject: Re: [PATCH v1 1/4] power: add uncore api to power library
> 
> On Mon, 11 Jul 2022 16:22:57 +0000
> tadhgkearney <tadhg.kearney@intel.com> wrote:
> 
> > +    FILE *f_cur_min;                     /**< FD of scaling_min */
> > +    FILE *f_cur_max;                     /**< FD of scaling_max */
> > +    FILE *f_base_min;                    /**< FD of initial min */
> > +    FILE *f_base_max;                    /**< FD of initial max */
> 
> Do you need to hold these extra FD's open?
> Also wasteful to use stdio for simple control sysfs like this.

Hi Stephen,
No these extra FD's don't need to be kept open, will remove their usage for v3.
What do you mean exactly by using stdio; are you suggesting to not make use of flush() calls,
or more broadly avoid stdio altogether?
Thanks,
Tadhg

Re: [PATCH v1 1/4] power: add uncore api to power library

[Stephen Hemminger]

On Thu, 14 Jul 2022 14:56:29 +0000
"Kearney, Tadhg" <tadhg.kearney@intel.com> wrote:

> > -----Original Message-----
> > From: Stephen Hemminger <stephen@networkplumber.org>
> > Sent: Monday 11 July 2022 17:37
> > To: Kearney, Tadhg <tadhg.kearney@intel.com>
> > Cc: dev@dpdk.org; dave.hunt@intel.com; Burakov, Anatoly
> > <anatoly.burakov@intel.com>; Pattan, Reshma <reshma.pattan@intel.com>
> > Subject: Re: [PATCH v1 1/4] power: add uncore api to power library
> > 
> > On Mon, 11 Jul 2022 16:22:57 +0000
> > tadhgkearney <tadhg.kearney@intel.com> wrote:
> >   
> > > +    FILE *f_cur_min;                     /**< FD of scaling_min */
> > > +    FILE *f_cur_max;                     /**< FD of scaling_max */
> > > +    FILE *f_base_min;                    /**< FD of initial min */
> > > +    FILE *f_base_max;                    /**< FD of initial max */  
> > 
> > Do you need to hold these extra FD's open?
> > Also wasteful to use stdio for simple control sysfs like this.  
> 
> Hi Stephen,
> No these extra FD's don't need to be kept open, will remove their usage for v3.
> What do you mean exactly by using stdio; are you suggesting to not make use of flush() calls,
> or more broadly avoid stdio altogether?
> Thanks,
> Tadhg

See eal_parse_sysfs_value.