Re: 2.6.17 regression: Very slow net transfer from some hosts

From: John Heffner
Date: Tue Apr 11 2006 - 15:24:19 EST


Daniel Drake wrote:
Hi,

Since sometime after 2.6.16, some websites have been very slow to load. Examples include:

http://zd1211.ath.cx
http://developer.osdl.org/shemminger/blog/
http://www.reactivated.net/weblog

On a good kernel, "wget http://zd1211.ath.cx"; says:
20:23:38 (90.44 KB/s) - `index.html' saved [20895/20895]

On a bad kernel:
20:14:18 (327.01 B/s) - `index.html' saved [20895/20895]

I reproduced this on two different internet connections (same ISP though). However I cannot reproduce it on my other system.

git-bisect tracked it down to:

7b4f4b5ebceab67ce440a61081a69f0265e17c2a is first bad commit
diff-tree 7b4f4b5ebceab67ce440a61081a69f0265e17c2a (from 2babf9daae4a3561f3264638a22ac7d0b14a6f52)
Author: John Heffner <jheffner@xxxxxxx>
Date: Sat Mar 25 01:34:07 2006 -0800

[TCP]: Set default max buffers from memory pool size

Indeed, reverting this patch from 2.6.17-rc1-git4 allows those sites to load again.

Any ideas?

I'm not seeing this behavior myself. What are the values of /proc/sys/net/ipv4/tcp_wmem, tcp_rmem, and tcp_mem? How much memory does this system have? (A binary tcpdump might be good, too.)

Thanks,
-John

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