Commit cc8c9d6c authored by Paolo Bonzini's avatar Paolo Bonzini Committed by Stefan Hajnoczi
Browse files

mirror: fix throttling delay calculation 



The throttling delay calculation was using an inaccurate sector count to
calculate the time to sleep.  This broke rate-limiting for the block
mirror job.

Move the delay calculation into mirror_iteration() where we know how
many sectors were transferred.  This lets us calculate an accurate delay
time.

Reported-by: default avatarJoaquim Barrera <jbarrera@ac.upc.edu>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
parent dc6fb73d

block/mirror.c

+15 −13
Original line number Diff line number Diff line
@@ -139,11 +139,12 @@ static void mirror_read_complete(void *opaque, int ret) 
                    mirror_write_complete, op);

}



static void coroutine_fn mirror_iteration(MirrorBlockJob *s)

static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s)

{

    BlockDriverState *source = s->common.bs;

    int nb_sectors, sectors_per_chunk, nb_chunks;

    int64_t end, sector_num, next_chunk, next_sector, hbitmap_next_sector;

    uint64_t delay_ns;

    MirrorOp *op;



    s->sector_num = hbitmap_iter_next(&s->hbi);
@@ -231,7 +232,12 @@ static void coroutine_fn mirror_iteration(MirrorBlockJob *s) 
        nb_chunks += added_chunks;

        next_sector += added_sectors;

        next_chunk += added_chunks;

    } while (next_sector < end);

        if (!s->synced && s->common.speed) {

            delay_ns = ratelimit_calculate_delay(&s->limit, added_sectors);

        } else {

            delay_ns = 0;

        }

    } while (delay_ns == 0 && next_sector < end);



    /* Allocate a MirrorOp that is used as an AIO callback.  */

    op = g_slice_new(MirrorOp);
@@ -268,6 +274,7 @@ static void coroutine_fn mirror_iteration(MirrorBlockJob *s) 
    trace_mirror_one_iteration(s, sector_num, nb_sectors);

    bdrv_aio_readv(source, sector_num, &op->qiov, nb_sectors,

                   mirror_read_complete, op);

    return delay_ns;

}



static void mirror_free_init(MirrorBlockJob *s)
@@ -362,7 +369,7 @@ static void coroutine_fn mirror_run(void *opaque) 
    bdrv_dirty_iter_init(bs, s->dirty_bitmap, &s->hbi);

    last_pause_ns = qemu_clock_get_ns(QEMU_CLOCK_REALTIME);

    for (;;) {

        uint64_t delay_ns;

        uint64_t delay_ns = 0;

        int64_t cnt;

        bool should_complete;
@@ -386,10 +393,12 @@ static void coroutine_fn mirror_run(void *opaque) 
                qemu_coroutine_yield();

                continue;

            } else if (cnt != 0) {

                mirror_iteration(s);

                delay_ns = mirror_iteration(s);

                if (delay_ns == 0) {

                    continue;

                }

            }

        }



        should_complete = false;

        if (s->in_flight == 0 && cnt == 0) {
@@ -432,17 +441,10 @@ static void coroutine_fn mirror_run(void *opaque) 
        }



        ret = 0;

        trace_mirror_before_sleep(s, cnt, s->synced);

        trace_mirror_before_sleep(s, cnt, s->synced, delay_ns);

        if (!s->synced) {

            /* Publish progress */

            s->common.offset = (end - cnt) * BDRV_SECTOR_SIZE;



            if (s->common.speed) {

                delay_ns = ratelimit_calculate_delay(&s->limit, sectors_per_chunk);

            } else {

                delay_ns = 0;

            }



            block_job_sleep_ns(&s->common, QEMU_CLOCK_REALTIME, delay_ns);

            if (block_job_is_cancelled(&s->common)) {

                break;

trace-events

+1 −1
Original line number Diff line number Diff line
@@ -82,7 +82,7 @@ mirror_start(void *bs, void *s, void *co, void *opaque) "bs %p s %p co %p opaque 
mirror_restart_iter(void *s, int64_t cnt) "s %p dirty count %"PRId64

mirror_before_flush(void *s) "s %p"

mirror_before_drain(void *s, int64_t cnt) "s %p dirty count %"PRId64

mirror_before_sleep(void *s, int64_t cnt, int synced) "s %p dirty count %"PRId64" synced %d"

mirror_before_sleep(void *s, int64_t cnt, int synced, uint64_t delay_ns) "s %p dirty count %"PRId64" synced %d delay %"PRIu64"ns"

mirror_one_iteration(void *s, int64_t sector_num, int nb_sectors) "s %p sector_num %"PRId64" nb_sectors %d"

mirror_iteration_done(void *s, int64_t sector_num, int nb_sectors, int ret) "s %p sector_num %"PRId64" nb_sectors %d ret %d"

mirror_yield(void *s, int64_t cnt, int buf_free_count, int in_flight) "s %p dirty count %"PRId64" free buffers %d in_flight %d"