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sched_deadline [2013/12/12 13:07]
claudio_scordino
sched_deadline [2014/06/03 05:43] (current)
claudio_scordino
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 The Linux kernel contains different scheduler classes. By default the kernel uses a scheduler mechanism called [[http://​en.wikipedia.org/​wiki/​Completely_Fair_Scheduler|Completely Fair Scheduler]],​ introduced in the 2.6.23 version of the kernel. Internally this default-scheduler class is also known as SCHED_OTHER. The standard Linux kernel also contains two real-time scheduling classes named SCHED_FIFO (realtime first-in-first-out) and SCHED_RR (realtime round-robin) both of which take precedence over the default class. The SCHED_DEADLINE patch adds a new scheduling class to the modular Linux scheduler, and implements the well-known [[http://​en.wikipedia.org/​wiki/​Earliest_deadline_first_scheduling|Earliest Deadline First (EDF) algorithm]]. The Linux kernel contains different scheduler classes. By default the kernel uses a scheduler mechanism called [[http://​en.wikipedia.org/​wiki/​Completely_Fair_Scheduler|Completely Fair Scheduler]],​ introduced in the 2.6.23 version of the kernel. Internally this default-scheduler class is also known as SCHED_OTHER. The standard Linux kernel also contains two real-time scheduling classes named SCHED_FIFO (realtime first-in-first-out) and SCHED_RR (realtime round-robin) both of which take precedence over the default class. The SCHED_DEADLINE patch adds a new scheduling class to the modular Linux scheduler, and implements the well-known [[http://​en.wikipedia.org/​wiki/​Earliest_deadline_first_scheduling|Earliest Deadline First (EDF) algorithm]].
- 
-The project was initially financed by the European commission through [[http://​www.actors-project.eu|the ACTORS FP7 project]]. The first version of the patch was called SCHED_EDF and [presented to the Linux kernel community in 2009. With this name was also [[http://​lwn.net/​images/​conf/​rtlws11/​papers/​proc/​p16.pdf|presented to the Real-Time Linux Workshop]] after a few weeks. The name has been then changed to SCHED_DEADLINE after [[https://​lkml.org/​lkml/​2009/​9/​22/​214|the request of the Linux kernel community]]. 
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-The project is carried out jointly by the [[http://​retis.sssup.it|Real-Time Systems Laboratory of Scuola Superiore Sant'​Anna]] and the [[http://​www.evidence.eu.com|company Evidence Srl]]. 
  
  
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-===== Releases ​ =====+===== History of the project ​ =====
  
  
-In the course ​of the years, the patch has been periodically released to the kernel community through the Linux Kernel Mailing List (LKML). Each release aligned the code to the latest version of the kernel and took into account comments received at the previous submission.+The initial idea of a Linux scheduling class based on the Earliest Deadline First (EDF) algorithm is born in the small context ​of the [[http://​retis.sssup.it|Real-Time Systems (ReTiS) Lab of Scuola Superiore Sant'​Anna]] and its Spin-Off company [[http://​www.evidence.eu.com|Evidence Srl]].  
 +ThenEvidence Srl leveraged the funding of the [[http://​www.actors-project.eu|ACTORS project]], supported by the European Commission through the FP7 framework programme, for financing and promoting the development of the first versions of the patch. 
 +The code has been developed by Dario Faggioli (for the first three versions) and Juri Lelli (since the fourth version) with sporadic help from Michael Trimarchi and Fabio Checconi. Claudio Scordino has been in charge of the initial coordination,​ supporting and project advertisement. Johan Eker has been in charge of coordination within ACTORS and supporting from Ericsson. The patch has been periodically released to the kernel community through the Linux kernel mailing list (LKML). Each release aligned the code to the latest version of the kernel and took into account comments received at the previous submission. As the popularity of the scheduler increased, a higher number of kernel developers started providing their feedback and their contribution.
  
-Currently, ​the following ​releases ​have been made:+The original version of the patch was called SCHED_EDF and [[https://​lkml.org/​lkml/​2009/​9/​22/​186|presented to the Linux kernel community in 2009]]. With this name was also [[http://​lwn.net/​images/​conf/​rtlws11/​papers/​proc/​p16.pdf|presented to the Real-Time Linux Workshop]] after a few weeks. The name has been then changed to SCHED_DEADLINE after [[https://​lkml.org/​lkml/​2009/​9/​22/​214|the request of the Linux kernel community]]. 
 + 
 +The following ​versions ​have been released:
  
   * The initial version of the scheduler was [[https://​lkml.org/​lkml/​2009/​9/​22/​186|submitted on September 22, 2009]] with the name of SCHED_EDF.   * The initial version of the scheduler was [[https://​lkml.org/​lkml/​2009/​9/​22/​186|submitted on September 22, 2009]] with the name of SCHED_EDF.
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 The project has been [[http://​lwn.net/​Articles/​570293/​|already integrated in the Yocto distribution]]. Moreover, there has been some [[https://​groups.google.com/​a/​linaro.org/​forum/#​!topic/​linaro-networking/​IDmDhH6JL8U|interest for inclusion in Linaro]] as well. The project has been [[http://​lwn.net/​Articles/​570293/​|already integrated in the Yocto distribution]]. Moreover, there has been some [[https://​groups.google.com/​a/​linaro.org/​forum/#​!topic/​linaro-networking/​IDmDhH6JL8U|interest for inclusion in Linaro]] as well.
  
-An [[http://​lwn.net/​Articles/​575497/​|article on the popular Linux Weekly News site]] ​has recently ​argued that SCHED_DEADLINE may be merged into the mainline kernel in the very next releases. ​+An [[http://​lwn.net/​Articles/​575497/​|article on the popular Linux Weekly News site]] argued that SCHED_DEADLINE may be merged into the mainline kernel in the very next releases.  
 + 
 +The code has been merged into the mainline kernel ([[http://​git.kernel.org/​linus/​a0fa1dd3cdbccec9597fe53b6177a9aa6e20f2f8|commit number a0fa1dd3cdbccec9597fe53b6177a9aa6e20f2f8]]) and therefore will be **available from kernel release 3.14**.
  
  
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-Several websites (e.g., OSNews, Slashdot, Linux Today, etc.) have talked about the project in the course of the years. ​+Several websites (e.g., OSNews, Slashdot, Linux Today, Phoronix, etc.) have talked about the project in the course of the years. ​
  
 Among the various websites, the best resources are: Among the various websites, the best resources are:
sched_deadline.1386853652.txt.gz · Last modified: 2013/12/12 13:07 by claudio_scordino