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Re: [Qemu-devel] [PATCH] block: fix bdrv_exceed_iops_limits wait computa
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] [PATCH] block: fix bdrv_exceed_iops_limits wait computation |
Date: |
Wed, 20 Mar 2013 16:12:03 +0100 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Wed, Mar 20, 2013 at 03:56:33PM +0100, Benoît Canet wrote:
> > 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;
> }
> ----------
The comment explains why slice_end needs to be extended, but not why
bs->slice_time should be changed (except that it was tuned as the result
of an experiment).
Zhi Yong: Do you remember a reason for modifying bs->slice_time?
Stefan
- [Qemu-devel] [PATCH] Fix I/O throttling pathologic oscillating behavior, Benoît Canet, 2013/03/20
- [Qemu-devel] [PATCH] block: fix bdrv_exceed_iops_limits wait computation, Benoît Canet, 2013/03/20
- Re: [Qemu-devel] [PATCH] block: fix bdrv_exceed_iops_limits wait computation, Zhi Yong Wu, 2013/03/20
- Re: [Qemu-devel] [PATCH] block: fix bdrv_exceed_iops_limits wait computation, Stefan Hajnoczi, 2013/03/20
- Re: [Qemu-devel] [PATCH] block: fix bdrv_exceed_iops_limits wait computation, Stefan Hajnoczi, 2013/03/20
- Re: [Qemu-devel] [PATCH] block: fix bdrv_exceed_iops_limits wait computation, Benoît Canet, 2013/03/20
- Re: [Qemu-devel] [PATCH] block: fix bdrv_exceed_iops_limits wait computation,
Stefan Hajnoczi <=
- Re: [Qemu-devel] [PATCH] block: fix bdrv_exceed_iops_limits wait computation, Zhi Yong Wu, 2013/03/20
- Re: [Qemu-devel] [PATCH] block: fix bdrv_exceed_iops_limits wait computation, Stefan Hajnoczi, 2013/03/21
- Re: [Qemu-devel] [PATCH] block: fix bdrv_exceed_iops_limits wait computation, Zhi Yong Wu, 2013/03/21
- Re: [Qemu-devel] [PATCH] block: fix bdrv_exceed_iops_limits wait computation, Stefan Hajnoczi, 2013/03/21
- Re: [Qemu-devel] [PATCH] block: fix bdrv_exceed_iops_limits wait computation, Benoît Canet, 2013/03/20
- Re: [Qemu-devel] [PATCH] block: fix bdrv_exceed_iops_limits wait computation, Stefan Hajnoczi, 2013/03/21
- Re: [Qemu-devel] [PATCH] block: fix bdrv_exceed_iops_limits wait computation, Benoît Canet, 2013/03/21