Lidong Chen <jemmy858...@gmail.com> wrote:
> when migration with quick speed, mig_save_device_bulk invoke
> bdrv_is_allocated too frequently, and cause vnc reponse slowly.
> this patch limit the time used for bdrv_is_allocated.
>
> Signed-off-by: Lidong Chen <lidongc...@tencent.com>
> ---
> migration/block.c | 39 +++++++++++++++++++++++++++++++--------
> 1 file changed, 31 insertions(+), 8 deletions(-)
>
> diff --git a/migration/block.c b/migration/block.c
> index 7734ff7..d3e81ca 100644
> --- a/migration/block.c
> +++ b/migration/block.c
> @@ -110,6 +110,7 @@ typedef struct BlkMigState {
> int transferred;
> int prev_progress;
> int bulk_completed;
> + int time_ns_used;
An int that can only take values 0/1 is called a bool O:-)
> if (bmds->shared_base) {
> qemu_mutex_lock_iothread();
> aio_context_acquire(blk_get_aio_context(bb));
> /* Skip unallocated sectors; intentionally treats failure as
> * an allocated sector */
> - while (cur_sector < total_sectors &&
> - !bdrv_is_allocated(blk_bs(bb), cur_sector,
> - MAX_IS_ALLOCATED_SEARCH, &nr_sectors)) {
> - cur_sector += nr_sectors;
> + while (cur_sector < total_sectors) {
> + clock_gettime(CLOCK_MONOTONIC_RAW, &ts1);
> + ret = bdrv_is_allocated(blk_bs(bb), cur_sector,
> + MAX_IS_ALLOCATED_SEARCH, &nr_sectors);
> + clock_gettime(CLOCK_MONOTONIC_RAW, &ts2);
Do we really want to call clock_gettime each time that
bdrv_is_allocated() is called? My understanding is that clock_gettime
is expensive, but I don't know how expensive is brdrv_is_allocated()
And while we are at it, .... shouldn't we check since before the while?
> +
> + block_mig_state.time_ns_used += (ts2.tv_sec - ts1.tv_sec) *
> BILLION
> + + (ts2.tv_nsec - ts1.tv_nsec);
> +
> + if (!ret) {
> + cur_sector += nr_sectors;
> + if (block_mig_state.time_ns_used > 100000) {
> + timeout_flag = 1;
> + break;
> + }
> + } else {
> + break;
> + }
> }
> aio_context_release(blk_get_aio_context(bb));
> qemu_mutex_unlock_iothread();
> @@ -292,6 +311,11 @@ static int mig_save_device_bulk(QEMUFile *f,
> BlkMigDevState *bmds)
> return 1;
> }
>
> + if (timeout_flag == 1) {
> + bmds->cur_sector = bmds->completed_sectors = cur_sector;
> + return 0;
> + }
> +
> bmds->completed_sectors = cur_sector;
>
> cur_sector &= ~((int64_t)BDRV_SECTORS_PER_DIRTY_CHUNK - 1);
> @@ -576,9 +600,6 @@ static int mig_save_device_dirty(QEMUFile *f,
> BlkMigDevState *bmds,
> }
>
> bdrv_reset_dirty_bitmap(bmds->dirty_bitmap, sector, nr_sectors);
> - sector += nr_sectors;
> - bmds->cur_dirty = sector;
> -
> break;
> }
> sector += BDRV_SECTORS_PER_DIRTY_CHUNK;
> @@ -756,6 +777,7 @@ static int block_save_iterate(QEMUFile *f, void *opaque)
> }
>
> blk_mig_reset_dirty_cursor();
> + block_mig_state.time_ns_used = 0;
>
> /* control the rate of transfer */
> blk_mig_lock();
> @@ -764,7 +786,8 @@ static int block_save_iterate(QEMUFile *f, void *opaque)
> qemu_file_get_rate_limit(f) &&
> (block_mig_state.submitted +
> block_mig_state.read_done) <
> - MAX_INFLIGHT_IO) {
> + MAX_INFLIGHT_IO &&
> + block_mig_state.time_ns_used <= 100000) {
changed this 10.000 (and the one used previously) to one constant that
says BIG_DELAY, 100MS or whatever you fancy.
Thanks, Juan.
