Re: Block device throttling [Re: Distributed storage.]

On Tuesday 14 August 2007 05:46, Evgeniy Polyakov wrote:

quoted

The throttling of the virtual device must begin in
generic_make_request and last to ->endio.  You release the throttle
of the virtual device at the point you remap the bio to an
underlying device, which you have convinced yourself is ok, but it
is not.  You seem to miss the fact that whatever resources the
virtual device has allocated are no longer protected by the
throttle count *of the virtual device*, or you do not

Because it is charged to another device.

Great.  You charged the resource to another device, but you did not 
limit the amount of resources that the first device can consume.  Which 
misses the whole point.

Regards,

Daniel