Implementation of dm-ioband as a dm-driver (Re: [dm-devel] [PATCH1/2] dm-ioband: I/O bandwidth controller v1.10.0: Source code and patch)

From: Ryo Tsuruta
Date: Wed Jan 28 2009 - 22:41:46 EST


Hi Vivek,

This mail is about implement IO controller as a dm-driver.

> In this case first you are forcing some functionalilty to go in a kernel
> module and then coming up with tools for configuration. I never understood
> that why don't you let the controller be inside the kernel, let it
> directly interact with cgroup subsystem and work instead of first taking
> the functionality out of kernel in a module and then justifying the case
> that now we need new ways of configuring that module because cgroup
> infrastructure is not sufficient.

It is possible the algorithm of dm-ioband can be directly implemented
in the kernel. I've been investigating how to do it.

> > > - Need of a dm device for every device we want to control
> > >
> > > - This requirement looks odd. It forces everybody to use dm-tools
> > > and if there are lots of disks in the system, configuation is
> > > pain.
> >
> > I don't think it's so pain. I think you are already using LVM devices on
> > your boxes. Setting up dm-ioband is the same as that for LVM. And some
> > scripts or something similar will help you set up them.
>
> Not everybody uses LVM. Balbir had asked once, if there are thousands of
> disks in the system, does that mean I need to create this dm-ioband device
> for all the disks?

I think it could be easily done by a small script of several lines.

Thanks,
Ryo Tsuruta
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