Commit d00e6923 authored by Alberto Garcia's avatar Alberto Garcia Committed by Stefan Hajnoczi
Browse files

throttle: Make LeakyBucket.avg and LeakyBucket.max integer types 



Both the throttling limits set with the throttling.iops-* and
throttling.bps-* options and their QMP equivalents defined in the
BlockIOThrottle struct are integer values.

Those limits are also reported in the BlockDeviceInfo struct and they
are integers there as well.

Therefore there's no reason to store them internally as double and do
the conversion everytime we're setting or querying them, so this patch
uses uint64_t for those types. Let's also use an unsigned type because
we don't allow negative values anyway.

LeakyBucket.level and LeakyBucket.burst_level do however remain double
because their value changes depending on the fraction of time elapsed
since the previous I/O operation.

Signed-off-by: default avatarAlberto Garcia <berto@igalia.com>
Message-id: f29b840422767b5be2c41c2dfdbbbf6c5f8fedf8.1503580370.git.berto@igalia.com
Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
parent 2a8be39e

include/qemu/throttle.h

+2 −2
Original line number Diff line number Diff line
@@ -77,8 +77,8 @@ typedef enum { 
 */



typedef struct LeakyBucket {

    double  avg;              /* average goal in units per second */

    double  max;              /* leaky bucket max burst in units */

    uint64_t avg;             /* average goal in units per second */

    uint64_t max;             /* leaky bucket max burst in units */

    double  level;            /* bucket level in units */

    double  burst_level;      /* bucket level in units (for computing bursts) */

    unsigned burst_length;    /* max length of the burst period, in seconds */

tests/test-throttle.c

+2 −1
Original line number Diff line number Diff line
@@ -284,13 +284,14 @@ static void test_enabled(void) 
    for (i = 0; i < BUCKETS_COUNT; i++) {

        throttle_config_init(&cfg);

        set_cfg_value(false, i, 150);

        g_assert(throttle_is_valid(&cfg, NULL));

        g_assert(throttle_enabled(&cfg));

    }



    for (i = 0; i < BUCKETS_COUNT; i++) {

        throttle_config_init(&cfg);

        set_cfg_value(false, i, -150);

        g_assert(!throttle_enabled(&cfg));

        g_assert(!throttle_is_valid(&cfg, NULL));

    }

}

util/throttle.c

+3 −4
Original line number Diff line number Diff line
@@ -106,13 +106,13 @@ int64_t throttle_compute_wait(LeakyBucket *bkt) 
        /* If bkt->max is 0 we still want to allow short bursts of I/O

         * from the guest, otherwise every other request will be throttled

         * and performance will suffer considerably. */

        bucket_size = bkt->avg / 10;

        bucket_size = (double) bkt->avg / 10;

        burst_bucket_size = 0;

    } else {

        /* If we have a burst limit then we have to wait until all I/O

         * at burst rate has finished before throttling to bkt->avg */

        bucket_size = bkt->max * bkt->burst_length;

        burst_bucket_size = bkt->max / 10;

        burst_bucket_size = (double) bkt->max / 10;

    }



    /* If the main bucket is full then we have to wait */
@@ -338,8 +338,7 @@ bool throttle_is_valid(ThrottleConfig *cfg, Error **errp) 


    for (i = 0; i < BUCKETS_COUNT; i++) {

        LeakyBucket *bkt = &cfg->buckets[i];

        if (bkt->avg < 0 || bkt->max < 0 ||

            bkt->avg > THROTTLE_VALUE_MAX || bkt->max > THROTTLE_VALUE_MAX) {

        if (bkt->avg > THROTTLE_VALUE_MAX || bkt->max > THROTTLE_VALUE_MAX) {

            error_setg(errp, "bps/iops/max values must be within [0, %lld]",

                       THROTTLE_VALUE_MAX);

            return false;