Subject: Re: Throttling IO Requests in NetBSD via Congestion Control
To: Sumantra Kundu <>
From: Thor Lancelot Simon <>
List: tech-kern
Date: 12/02/2006 11:34:08
On Sat, Dec 02, 2006 at 01:50:37AM -0600, Sumantra Kundu wrote:
> I have made considerable changes to the congestion control (CC)
> algorithm. It can be considered version 2 (version 1 being CC inside
> UVM alone).
> In version 2, the CC algorithm resides inside the IO scheduler. It
> monitors the dynamics of the two queues: read and write; only when it
> thinks that the write queue is being filled at a rate that might
> indicate congestion,  it nails down the process that has initiated
> most of the write request in the queue and puts it to sleep.

That's great news.  How does it decide what rate might indicate congestion?