http://www.osnews.com/story/24223/Alternative_to_the_200_Lines_Kernel_Patch_that_Does_Wonders_ Exploring the Future of Computing en-us Copyright 2001-2013, David Adams adam+nospam@osnews.com Sat, 25 May 2013 01:59:59 GMT http://www.osnews.com/images/osnews.gif http://www.osnews.com http://www.osnews.com/thread?456428 http://www.osnews.com/thread?456428 It's how the feature was tested before being implemented as an automatism in the kernel, so it's not very surprising that it works.Edited 2011-01-08 00:19 UTC Sat, 08 Jan 2011 00:19:00 GMT donotreply@osnews.com (diegocg) Comments http://www.osnews.com/thread?456431 http://www.osnews.com/thread?456431 Old.

I read the same like 3 months ago. Sat, 08 Jan 2011 00:29:00 GMT donotreply@osnews.com (Hiev) Comments http://www.osnews.com/thread?456434 http://www.osnews.com/thread?456434 Yes, very old. The link is even dated in the url, and is plainly dated once you get there and read it (Nov 18th, 2010). Maybe it was never posted on osnews, I don't remember, but it certainly made the rounds everywhere else.Edited 2011-01-08 00:47 UTC Sat, 08 Jan 2011 00:45:00 GMT donotreply@osnews.com (galvanash) Comments http://www.osnews.com/thread?456444 http://www.osnews.com/thread?456444 and works with systemd only Sat, 08 Jan 2011 01:11:00 GMT donotreply@osnews.com (somebody) Comments http://www.osnews.com/thread?456455 http://www.osnews.com/thread?456455 yup (I think systemd 10+ only, in fact). Sat, 08 Jan 2011 02:43:00 GMT donotreply@osnews.com (AdamW) Comments http://www.osnews.com/thread?456491 http://www.osnews.com/thread?456491 So what if it's "old" news.
Not all of us frequent dozens of IT sites.

It's note worthy enough for archiving purposes alone.Edited 2011-01-08 12:33 UTC Sat, 08 Jan 2011 12:31:00 GMT donotreply@osnews.com (fran) Comments http://www.osnews.com/thread?456518 http://www.osnews.com/thread?456518 Hi, does this work only for programs started from the shell? What about for a regular GUI desktop environment?
Thanks! Sat, 08 Jan 2011 18:13:00 GMT donotreply@osnews.com (sb56637) Comments http://www.osnews.com/thread?456528 http://www.osnews.com/thread?456528 Bull crap. cgroups has nothing to do with systemd. You have your dependencies backwards. Sat, 08 Jan 2011 19:26:00 GMT donotreply@osnews.com (FishB8) Comments http://www.osnews.com/thread?456529 http://www.osnews.com/thread?456529 The setup in the linked article is designed to create a new cgroup for each new shell (and their child processes).

There is nothing to stop you from creating cgroups of your own design though. Sat, 08 Jan 2011 19:32:00 GMT donotreply@osnews.com (FishB8) Comments http://www.osnews.com/thread?456763 http://www.osnews.com/thread?456763 What I deplore is what I've always deplored with the Linux community in specific and the computing world in general: a simple explanation of what happens is nowhere to be found. Somehow, we are just supposed to be marveled at it if (and especially when) we don't know exactly what is going on.

There isn't even a mention of what the "200 lines" in question do. I've seen the news item when posted here on OSnews, and I remember following the link and reading the linked article. That was some time ago. And now, you have to click links up to Phoronix before reading that the procedure is for enhancing the responsiveness of Linux.

Anyway, the linked article sucks in my opinion as it reminds me of that "leave'em in the dark" or "if you don't already know then it's not for you" attitude.Edited 2011-01-10 11:28 UTC Mon, 10 Jan 2011 11:28:00 GMT donotreply@osnews.com (vodoomoth) Comments http://www.osnews.com/thread?456780 http://www.osnews.com/thread?456780 To find out what the "200 lines" patch did was easy, and I did it when the article was first published; you simply had to go to the LKML thread on the topic and read it. No understanding of C was required. You can go back and do that now, if you like.

What's more, this shell script approach was brought up in that very same LKML thread at that time and how it works was described to some extent.

Some understanding of CPU scheduling in general and Linux cgroups in particular is helpful to understand what's going on here. So...

Official Kernel documentation on CGroups:
http://www.mjmwired.net/kernel/Documentation/cgroups.txt

Not recommended as an introduction, but if you miss details elsewhere this is for you.

Red Hat CGroups documentation:
http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/R...

And from the simple end, wikipedia:
http://en.wikipedia.org/wiki/Cgroups

Now that you understand what cgroups are, let's get ni to the patch:

Here's the LWN article covering the feature from the "200 line" patch, which explains it in some detail and the discussion around it:
http://lwn.net/Articles/415740/

Here's the original LKML thread, which by now is scarily-long. I still recommend it since it's the primary source:
http://thread.gmane.org/gmane.linux.kernel/1050575

Specifically, look at this post for the origin of the shell script version referenced by this very-late article:
http://article.gmane.org/gmane.linux.kernel/1063263

Now you, too, can be in the loop! Mon, 10 Jan 2011 13:43:00 GMT donotreply@osnews.com (sorpigal) Comments http://www.osnews.com/thread?456781 http://www.osnews.com/thread?456781 This is the kind of news that should have been an addendum to the original article, or posted the next day. The alternative was posted on November 16th, which is the same day as the original OS News coverage, but several hours earlier. Mon, 10 Jan 2011 13:47:00 GMT donotreply@osnews.com (sorpigal) Comments http://www.osnews.com/thread?456793 http://www.osnews.com/thread?456793 Thank you for this comprehensive post although I wasn't asking for references (but I will read them) but just pointing out the lack of reader-friendliness and immediate information. When I read the linked article and its comments, it felt obvious that some information was missing. Thanks. Mon, 10 Jan 2011 15:03:00 GMT donotreply@osnews.com (vodoomoth) Comments http://www.osnews.com/thread?456856 http://www.osnews.com/thread?456856 Old news to the propeller heads, new to me. If it's old news to you skip the article fgs. The first one to stay "old news been there done that" gets a gold star! Mon, 10 Jan 2011 22:14:00 GMT donotreply@osnews.com (Bringbackanonposting) Comments