Re: [Qemu-devel] [PATCH] block: fix bdrv_exceed_iops_limits wait computation

[Benoît Canet]

> But I don't understand why bs->slice_time is modified instead of keeping
> it constant at 100 ms:
>
>     bs->slice_time = wait_time * BLOCK_IO_SLICE_TIME * 10;
>     bs->slice_end += bs->slice_time - 3 * BLOCK_IO_SLICE_TIME;
>     if (wait) {
>         *wait = wait_time * BLOCK_IO_SLICE_TIME * 10;
>     }

In bdrv_exceed_bps_limits there is an equivalent to this with a comment.

---------
  /* When the I/O rate at runtime exceeds the limits,
     * bs->slice_end need to be extended in order that the current statistic
     * info can be kept until the timer fire, so it is increased and tuned
     * based on the result of experiment.
     */
    bs->slice_time = wait_time * BLOCK_IO_SLICE_TIME * 10;
    bs->slice_end += bs->slice_time - 3 * BLOCK_IO_SLICE_TIME;
    if (wait) {
        *wait = wait_time * BLOCK_IO_SLICE_TIME * 10;
    }
----------

Yes I will try your patch.

Regards

Benoît