Re: [squid-users] doubt regarding delay pool

From: Henrik Nordstrom <hno@dont-contact.us>
Date: Tue, 1 Mar 2005 22:31:43 +0100 (CET)

On Sun, 27 Feb 2005, Dinil Divakaran wrote:

> Yes, you are right. But, because of this TCP sender sends packets till the
> window size shrinks to zero and therefore the downloading speed (the speed
> at which TCP packets are received) is not in control. It particular, it is
> never equal to the limit that we configure using the squid delay parameters.
> Only the average downloading speed will be equal to the limit that we want;
> not the bytes that are send per second.

A TCP is not allowed to shrink the window below the sequence number
already advertised.

What you can do is to not allow the window to grow very large to begin
with. Set by tcp_recv_bufsize or the TCP/IP parameters in your OS.

> No. I have done a tcpdump on the squid server to see find that the squid
> delay
> pool does not deliver a specific rate per second. It can deliver only a
> specific
> average rate, i.e, average rate of the transfer.

Yes. It is not meant to deliver an exact rate. The mainpurpose is to limit
bandwidth hoggers to allow others access to the available bandwidth.

But yes, it can be improved by dynamically adjusting the receive window
to the allowable size of the delay pool. Patch welcome.

Regards
Henrik
Received on Tue Mar 01 2005 - 14:31:53 MST

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