Re: [Qemu-devel] [PATCH V7 0/5] Continuous Leaky Bucket Throttling

[Benoît Canet]

> Here is my understanding of how the algorithm works:
> 
> There is a "max" burst value which is a guaranteed allowance.  If max is
> 100 units then you can always use up to 100 units without being
> throttled.
> 
> After the max burst value has been exceeded, requests are throttled down
> to the "avg" rate value.  The way it works is like this:
> 
> 1. If the max hasn't been reached, allow the request through.
> 2. If the max has been reached, schedule a timer for when the bucket
>    level comes back down to max.
> 3. Increment bucket level when the request is allowed through.
> 4. Drain bucket level according to avg rate as time passes.

Another point is that the initial ability to burst replenish when the guest does
not do any I/Os.

One usage of this is compute intensive tasks where slice of time are dedicated
to computations and separated by a flush to disk of the resulting data.

Best regards

Benoît