netdev - Re: TCP connection stops after high load.

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <7e63f56c0704150514q3b1271e8lcc9e8f30387d7540@mail.gmail.com>
Date:	Sun, 15 Apr 2007 15:14:44 +0300
From:	"Robert Iakobashvili" <coroberti@...il.com>
To:	"David Miller" <davem@...emloft.net>
Cc:	netdev@...r.kernel.org, greearb@...delatech.com
Subject: Re: TCP connection stops after high load.

On 4/13/07, David Miller <davem@...emloft.net> wrote:
> From: "Robert Iakobashvili" <coroberti@...il.com>
> Date: Thu, 12 Apr 2007 23:11:14 +0200
>
> > It works good with  2.6.11.8 and debian 2.6.18.3-i686 image.
> >
> > At the same Intel Pentium-4 PC with the same about kernel configuration
> > (make oldconfig using Debian config-2.6.18.3-i686) the setup fails with the
> > tcp-connections stalled after 1000 established connections when the kernel
> > is 2.6.20.6 or 2.6.19.5.
> >
> > It stalls even earlier, when lighttpd used with the default (poll ())
> > demultiplexing
> > after 500 connections or when apache2 web server used (memory?) - after 100
> > connections.
> >
> > I am currently going to try vanilla 2.6.18.3 and, if with it also
> > fails, to look through
> > Debian patches, trying to figure out, what is the delta.

Vanilla 2.6.18.3 works for me perfectly, whereas 2.6.19.5 and
2.6.20.6 do not.

Looking into the tcp /proc entries of 2.6.18.3 versus 2.6.19.5
tcp_rmem and tcp_wmem are the same, whereas tcp_mem are
much different:

kernel                  tcp_mem
---------------------------------------
2.6.18.3    12288 16384 24576
2.6.19.5      3072    4096   6144


Is not it done deliberately by the below patch:

commit 9e950efa20dc8037c27509666cba6999da9368e8
Author: John Heffner <jheffner@....edu>
Date:   Mon Nov 6 23:10:51 2006 -0800

    [TCP]: Don't use highmem in tcp hash size calculation.

    This patch removes consideration of high memory when determining TCP
    hash table sizes.  Taking into account high memory results in tcp_mem
    values that are too large.

Is it a feature?

My machine has:
MemTotal:       484368 kB
and
for all kernel configurations are actually the same with
CONFIG_HIGHMEM4G=y

Thanks,

-- 
Sincerely,
Robert Iakobashvili,
coroberti %x40 gmail %x2e com
...................................................................
Navigare necesse est, vivere non est necesse
...................................................................
http://curl-loader.sourceforge.net
An open-source HTTP/S, FTP/S traffic
generating, and web testing tool.
-
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html