powertop/common/turbo.c

/*
 * Copyright 2009, Intel Corporation
 * Copyright (c) 2009, 2012, Oracle and/or its affiliates. All rights reserved.
 *
 * This file is part of PowerTOP
 *
 * This program file is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; version 2 of the License.
 *
 * This program is distributed in the hope that 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program in a file named COPYING; if not, write to the
 * Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301 USA
 *
 * Authors:
 *  Arjan van de Ven <arjan@linux.intel.com>
 *  Eric C Saxe <eric.saxe@sun.com>
 *  Aubrey Li <aubrey.li@intel.com>
 */

/*
 * GPL Disclaimer
 *
 * For the avoidance of doubt, except that if any license choice other
 * than GPL or LGPL is available it will apply instead, Sun elects to
 * use only the General Public License version 2 (GPLv2) at this time
 * for any software where a choice of GPL license versions is made
 * available with the language indicating that GPLv2 or any later
 * version may be used, or where a choice of which version of the GPL
 * is applied is otherwise unspecified.
 */

#include <stdlib.h>
#include <string.h>
#include <dtrace.h>
#include <kstat.h>
#include <errno.h>
#include "powertop.h"

/*
 * Global turbo related variables definitions
 */
boolean_t       g_turbo_supported;
double          g_turbo_ratio;

/*
 * The variables to store kstat snapshot
 */
static turbo_info_t *cpu_turbo_info = NULL;
static turbo_info_t *t_new = NULL;

/*
 * Perform setup necessary to enumerate and track CPU turbo information
 */
static int
pt_turbo_init(void)
{
    kstat_t         *ksp;
    kstat_named_t       *knp;

    /*
     * check if the CPU turbo is supported
     */

    ksp = kstat_lookup(g_kc, "turbo", 0, NULL);
    if (ksp == NULL) {
        g_turbo_supported = B_FALSE;
        return (-1);
    }

    (void) kstat_read(g_kc, ksp, NULL);

    knp = pt_kstat_data_lookup(ksp, "turbo_supported",
        &g_turbo_supported_index);
    if (knp == NULL) {
        pt_error("couldn't find 'turbo_supported' kstat\n");
        g_turbo_supported = B_FALSE;
        return (-2);
    }

    /*
     * Initialize turbo information structure if turbo mode is supported
     */
    if (knp->value.ui32) {
        g_turbo_supported = B_TRUE;
        cpu_turbo_info = calloc((size_t)g_ncpus, sizeof (turbo_info_t));
        t_new = calloc((size_t)g_ncpus, sizeof (turbo_info_t));
    }

    return (0);
}

/*
 * Take a snapshot of each CPU's turbo information
 * by looking through the turbo kstats.
 */
static int
pt_turbo_snapshot(turbo_info_t *turbo_snapshot)
{
    kstat_t         *ksp;
    kstat_named_t       *knp;
    int             cpu;
    turbo_info_t        *turbo_info;

    for (cpu = 0; cpu < g_ncpus; cpu++) {
        turbo_info = &turbo_snapshot[cpu];
        ksp = kstat_lookup(g_kc, "turbo", g_cpu_table[cpu], NULL);
        if (ksp == NULL) {
            pt_error("couldn't find 'turbo' kstat for CPU %d\n",
                cpu);
            return (-1);
        }

        if (kstat_read(g_kc, ksp, NULL) == -1) {
            pt_error("couldn't read 'turbo' kstat for CPU %d\n",
                cpu);
            return (-2);
        }

        knp = pt_kstat_data_lookup(ksp, "turbo_mcnt",
            &g_turbo_mcnt_index);
        if (knp == NULL) {
            pt_error("couldn't find 'turbo_mcnt' kstat for CPU "
                "%d\n", cpu);
            return (-3);
        }

        /*
         * snapshot IA32_MPERF_MSR
         */
        turbo_info->t_mcnt = knp->value.ui64;

        knp = pt_kstat_data_lookup(ksp, "turbo_acnt",
            &g_turbo_acnt_index);
        if (knp == NULL) {
            pt_error("couldn't find 'turbo_acnt' kstat for CPU "
                "%d\n", cpu);
            return (-4);
        }

        /*
         * snapshot IA32_APERF_MSR
         */
        turbo_info->t_acnt = knp->value.ui64;
    }

    return (0);
}

/*
 * Turbo support checking and information initialization
 */
int
pt_turbo_stat_prepare(void)
{
    int ret = 0;

    if ((ret = pt_turbo_init()) != 0)
        return (ret);

    if ((ret = pt_turbo_snapshot(cpu_turbo_info)) != 0)
        pt_error("failed to snapshot 'turbo' kstat\n");

    return (ret);
}

/*
 * When doing the statistics collection, we compare two kstat snapshot
 * and get a delta. the final ratio of performance boost will be worked
 * out according to the kstat delta
 */
int
pt_turbo_stat_collect(void)
{
    int     cpu;
    uint64_t    delta_mcnt, delta_acnt;
    double      ratio;
    int     ret;

    /*
     * Take a snapshot of turbo information to setup turbo_info_t
     * structure
     */
    if ((ret = pt_turbo_snapshot(t_new)) != 0) {
        pt_error("failed to snapshot 'turbo' kstat\n");
        return (ret);
    }

    /*
     * Calculate the kstat delta and work out the performance boost ratio
     */
    for (cpu = 0; cpu < g_ncpus; cpu++) {
        delta_mcnt = t_new[cpu].t_mcnt - cpu_turbo_info[cpu].t_mcnt;
        delta_acnt = t_new[cpu].t_acnt - cpu_turbo_info[cpu].t_acnt;

        if ((delta_mcnt > delta_acnt) || (delta_mcnt == 0))
            ratio = 1.0;
        else
            ratio = (double)delta_acnt / (double)delta_mcnt;
        g_turbo_ratio += ratio;
    }

    g_turbo_ratio = g_turbo_ratio / (double)g_ncpus;

    /*
     * Update the structure of the kstat for the next time calculation
     */
    (void) memcpy(cpu_turbo_info, t_new, g_ncpus * (sizeof (turbo_info_t)));

    return (0);
}