block/accounting.c

/*
 * QEMU System Emulator block accounting
 *
 * Copyright (c) 2011 Christoph Hellwig
 * Copyright (c) 2015 Igalia, S.L.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include "qemu/osdep.h"
#include "block/accounting.h"
#include "block/block_int.h"
#include "qemu/timer.h"
#include "sysemu/qtest.h"

static QEMUClockType clock_type = QEMU_CLOCK_REALTIME;
static const int qtest_latency_ns = NANOSECONDS_PER_SECOND / 1000;

void block_acct_init(BlockAcctStats *stats, bool account_invalid,
                     bool account_failed)
{
    stats->account_invalid = account_invalid;
    stats->account_failed = account_failed;

    if (qtest_enabled()) {
        clock_type = QEMU_CLOCK_VIRTUAL;
    }
}

void block_acct_cleanup(BlockAcctStats *stats)
{
    BlockAcctTimedStats *s, *next;
    QSLIST_FOREACH_SAFE(s, &stats->intervals, entries, next) {
        g_free(s);
    }
}

void block_acct_add_interval(BlockAcctStats *stats, unsigned interval_length)
{
    BlockAcctTimedStats *s;
    unsigned i;

    s = g_new0(BlockAcctTimedStats, 1);
    s->interval_length = interval_length;
    QSLIST_INSERT_HEAD(&stats->intervals, s, entries);

    for (i = 0; i < BLOCK_MAX_IOTYPE; i++) {
        timed_average_init(&s->latency[i], clock_type,
                           (uint64_t) interval_length * NANOSECONDS_PER_SECOND);
    }
}

BlockAcctTimedStats *block_acct_interval_next(BlockAcctStats *stats,
                                              BlockAcctTimedStats *s)
{
    if (s == NULL) {
        return QSLIST_FIRST(&stats->intervals);
    } else {
        return QSLIST_NEXT(s, entries);
    }
}

void block_acct_start(BlockAcctStats *stats, BlockAcctCookie *cookie,
                      int64_t bytes, enum BlockAcctType type)
{
    assert(type < BLOCK_MAX_IOTYPE);

    cookie->bytes = bytes;
    cookie->start_time_ns = qemu_clock_get_ns(clock_type);
    cookie->type = type;
}

void block_acct_done(BlockAcctStats *stats, BlockAcctCookie *cookie)
{
    BlockAcctTimedStats *s;
    int64_t time_ns = qemu_clock_get_ns(clock_type);
    int64_t latency_ns = time_ns - cookie->start_time_ns;

    if (qtest_enabled()) {
        latency_ns = qtest_latency_ns;
    }

    assert(cookie->type < BLOCK_MAX_IOTYPE);

    stats->nr_bytes[cookie->type] += cookie->bytes;
    stats->nr_ops[cookie->type]++;
    stats->total_time_ns[cookie->type] += latency_ns;
    stats->last_access_time_ns = time_ns;

    QSLIST_FOREACH(s, &stats->intervals, entries) {
        timed_average_account(&s->latency[cookie->type], latency_ns);
    }
}

void block_acct_failed(BlockAcctStats *stats, BlockAcctCookie *cookie)
{
    assert(cookie->type < BLOCK_MAX_IOTYPE);

    stats->failed_ops[cookie->type]++;

    if (stats->account_failed) {
        BlockAcctTimedStats *s;
        int64_t time_ns = qemu_clock_get_ns(clock_type);
        int64_t latency_ns = time_ns - cookie->start_time_ns;

        if (qtest_enabled()) {
            latency_ns = qtest_latency_ns;
        }

        stats->total_time_ns[cookie->type] += latency_ns;
        stats->last_access_time_ns = time_ns;

        QSLIST_FOREACH(s, &stats->intervals, entries) {
            timed_average_account(&s->latency[cookie->type], latency_ns);
        }
    }
}

void block_acct_invalid(BlockAcctStats *stats, enum BlockAcctType type)
{
    assert(type < BLOCK_MAX_IOTYPE);

    /* block_acct_done() and block_acct_failed() update
     * total_time_ns[], but this one does not. The reason is that
     * invalid requests are accounted during their submission,
     * therefore there's no actual I/O involved. */

    stats->invalid_ops[type]++;

    if (stats->account_invalid) {
        stats->last_access_time_ns = qemu_clock_get_ns(clock_type);
    }
}

void block_acct_merge_done(BlockAcctStats *stats, enum BlockAcctType type,
                      int num_requests)
{
    assert(type < BLOCK_MAX_IOTYPE);
    stats->merged[type] += num_requests;
}

int64_t block_acct_idle_time_ns(BlockAcctStats *stats)
{
    return qemu_clock_get_ns(clock_type) - stats->last_access_time_ns;
}

double block_acct_queue_depth(BlockAcctTimedStats *stats,
                              enum BlockAcctType type)
{
    uint64_t sum, elapsed;

    assert(type < BLOCK_MAX_IOTYPE);

    sum = timed_average_sum(&stats->latency[type], &elapsed);

    return (double) sum / elapsed;
}