lkml.org 
[lkml]   [2003]   [Feb]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: problems achieving decent throughput with latency.
David S. Miller wrote:
> From: Ben Greear <greearb@candelatech.com>
> Date: Mon, 03 Feb 2003 23:50:05 -0800
>
> Why would it use the maximum socket for a connection with low to
> no acks, ie low to no throughput?
>
> You open up the congestion window by ACK'ing a few windows
> worth of data, then you stop ACK'ing.

I think I understand, but on my system it seem to take 5-8 seconds for
the bandwidth to get up to ~20Mbps (with my larger buffer settings mentioned
earlier). This is with 25ms latency. With the default settings I can run about
8Mbps, so it would appear to me that only 3x the current default buffer settings
should get a window size enough to go ~20Mbps at 25ms latency.

Am I correct that if I have 10k clients doing their worst tricks, and
3 * (80k, my default according to the kernel) == 240k, then I have at most
2.4MB denial of service? Assuming 60k clients, that is only about 15MB
of DoS? If true, that is a fairly small time DoS considering the RAM available
on today's machines.

You claim for a very large N that the denial of service can happen. I
am just trying to understand the upper bound of N, and thus the upperbound
of the memory consumption assuming each connection is using it's maximum
buffer size.

Thanks,
Ben

--
Ben Greear <greearb@candelatech.com> <Ben_Greear AT excite.com>
President of Candela Technologies Inc http://www.candelatech.com
ScryMUD: http://scry.wanfear.com http://scry.wanfear.com/~greear


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:32    [W:0.048 / U:1.860 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site