[dm-devel] Re: IO scheduler based IO controller V10

[Ryo Tsuruta <ryov valinux co jp>]

Hi Rik,

Rik van Riel <riel redhat com> wrote:
> Ryo Tsuruta wrote:
> 
> > Because dm-ioband provides faireness in terms of how many IO requests
> > are issued or how many bytes are transferred, so this behaviour is to
> > be expected. Do you think fairness in terms of IO requests and size is
> > not fair?
> 
> When there are two workloads competing for the same
> resources, I would expect each of the workloads to
> run at about 50% of the speed at which it would run
> on an uncontended system.
> 
> Having one of the workloads run at 95% of the
> uncontended speed and the other workload at 5%
> is "not fair" (to put it diplomatically).

As I wrote in the mail to Vivek, I think that providing multiple
policies, on a per disk time basis, on a per iosize basis, maximum
rate limiting or etc would be good for users.

Thanks,
Ryo Tsuruta