Talkback

Date: Wed, 16 Apr 2008 17:48:06 -0500
From: Edward Blaize <[email protected]>
To: [email protected]
Subject: 5400 series averatec & linux.

-- 
* Ben Okopnik * Editor-in-Chief, Linux Gazette * http://LinuxGazette.NET *

From: René Pfeiffer <[email protected]>
Date: Sun, 30 Mar 2008 20:26:00 +0200
To: Erik van Zijst <[email protected]>
Subject: Re: Scalable TCP Tuning
Message-ID: <[email protected]>

> Hi Rene,
>
> I read some of your Linux Gazette articles, specifically the one on TCP's 
> pluggable congestion control and maybe you can give me a little push in the 
> right direction.
>
> I'm in a startup doing streaming video over TCP (rather than UDP with 
> forward error correction), but TCP is giving me some latency headaches. To 
> ensure uninterrupted playback, we use a chunky client-side playback buffer, 
> but in its relentless quest for throughput-optimization, often under high 
> bandwidth and transcontinental RTT's, TCP manages to introduce enough 
> latency to underrun any buffer.
>
> With streaming video, keeping latency within bounds is often more important 
> than squeezing out a few percent extra throughput. I've looked at the 
> pluggable congestion control algorithms which are great, but pretty much all 
> of them focus on high throughput, rather than latency.

> TCP maintains the dynamic send buffer between user- and kernel-space and in 
> order to minimize context switches, Linux seems to have a tendency to making 
> these really large. On high-latency, transcontinental connections, I often 
> get 1MB+ send buffers that can easily contain over 10 seconds of video. From 
> what I see, the kernel modules mostly seem to tune only the size of the cwnd 
> within the send buffer, rather than the send buffer as a whole, but since 
> this is probably the main cause for increased latency, I'm looking for a way 
> to tune this and always keep it as small as possible. Linux already seems to 
> increase the send buffer's capacity when the cwnd increases, but never seems 
> to shrink it again.
>
> Would you have any tips for a Linux-based startup when it comes to 
> low-latency TCP tuning?

> Hi there
>
> I am new to Linux, but with a big desire to become better. I have recently
> read your article "2-cent tips: convert the collection of your mp3 files
> into ogg"
> in Linux Gazzete. I have found it very interesting, and I wanted to try it
> out for myself. Everything went fine, except the script for replacing the "
> " (blanks) with "_".
>  After a little digging, and study of sed command, I have found out that the
> problem came from this line of code:
>
> do mv -v "$a" $(echo $a | sed s/\/\_/g);
>
> So I have replaced it with:
>
>  do mv -v "$a" $(echo $a | sed s/" "/\_/g);

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Date: Thu, 10 Apr 2008 23:03:36 +0200
From: Arnold Mashava <[email protected]>
To: [email protected]
Subject: Talkback:133/luana.html

-- 
* Ben Okopnik * Editor-in-Chief, Linux Gazette * http://LinuxGazette.NET *

> Hi Rene.
>
> My name is Pawel and firstly I'd like to thank you for your contribution
> into open source, for sharing knowledge.

> I've read your article on as in subject of this email. Ihave to mention
> don't know much about ldap and postfix much,
> I do my best to change that state of affairs. I wonder if you could
> briefly advise, put me on right line of thought.
> This is a problem I've come across:
> when I run your script:
>
> ../cgate_migrate_ldap.pl --source ubuntu --target localhost --verbose 4
> Connected to source server :   ubuntu
> Connected to target server :   localhost
> account has been moved to a remote system at ./cgate_migrate_ldap.pl
> line 174, <DATA> line 228.

> I'm not sure if I understand it correctly when in the article you say:
> "...
> We use the LDAP tree of our organisation dc=example,dc=net and create a
> subtree for all our accounts.
> Then we create another subtree for the Postfix settings... "
>
> Do you mean here the actual creation of the structure you mention just
> just after, creation with help of
> ldap client tools like, ldapadd, ldapmodify. And I get above error
> because I did not do it?

> In case that is not the reason for the error I get, here is some info on
> systems I work on:
> cgpro 4.1.8 on ubuntu 2.6.20-16-server and target machine is fedora 8
> 2.6.24.3-12.fc8 with openLdap 2.3.39

> Sorry if I got so straight to the point, I hope you don't find it impolite.

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> http://linuxgazette.net/116/herrmann.html

> I have the complete perl script.

> 1 matter eludes me - i do not understand -
> Where is the info to tell the program where to find a dir of images.

  img2ooImpress.pl
  Usage:
  img2ooImpress.pl ImageFileList [outputfile.odp]
  ImageFileList is a file containing all images to import

ls image*.jpg > filelist

running img2ooImpress.pl filelist

> i see this
> my $imgFileList=shift;how is this imagefile list made? I am expecting

> to see a path to a dir of images....I have just reread your code
> before sending this and Think I might understand now.the usage
> img2ooImpress.pl ImageFileList [outputfile.swi]the perl prog     then
> a txtfile   [ and this is optional? ]and then should the
> imageFileList be in the same dir with the perl?

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The Free International Online Linux Monthly	ISSN: 1934-371X	Main site: http://linuxgazette.net

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