Editing JACK Audio Connection Kit (section)

== Low-latency scheduling ==
[[File:Linux kernel and daemons with exclusive access.svg|thumb|Like [[PulseAudio]], JACK daemon is an "audio daemon", i.e. it does mixing of audio from applications via software. For this it assumes to have exclusive access to the kernel's audio sub-system.]]

The [[Scheduling (computing)|scheduling]] requirements of JACK to achieve sufficiently low latencies were one of the driving forces behind the [[real-time operating system|real-time]] optimization effort for the [[Linux kernel]] 2.6 series,<ref>{{cite web |url=https://lkml.org/lkml/2004/7/9/138 |title=Original announcement of a voluntary pre-emption patch for the Linux 2.6 kernel series by Ingo Molnar, 2004 |publisher=lkml.org |access-date=17 February 2010}}</ref><ref>{{cite web |url=https://lwn.net/images/conf/rtlws11/papers/proc/p02.pdf |title=Finding Origins of Latencies Using Ftrace, paper by Steven Rostedt from the Real-time Workshop 2009 |access-date=17 February 2010}}</ref> whose initial latency performance had been disappointing compared to the older 2.4 series.<ref>{{cite web |url=http://lac.zkm.de/2006/papers/lac2006_lee_revell.pdf |title=Real-time audio vs. 2.6, Linux Audio Conference 2006 paper by Lee Revell |access-date=17 February 2010 |archive-date=10 November 2020 |archive-url=https://web.archive.org/web/20201110045534/http://lac.zkm.de/2006/papers/lac2006_lee_revell.pdf |url-status=dead }}</ref> Real-time tuning work culminated in numerous scheduling improvements to the mainline kernel and the creation of an -rt branch for more intrusive optimizations in the release 2.6.24, and later the [[PREEMPT_RT|CONFIG_PREEMPT_RT patch]].<ref>{{cite web |url=http://rt.wiki.kernel.org/ |title=Real-Time Linux Wiki |publisher=[[Kernel.org]] (The Linux Kernel Archives) |access-date=8 June 2010}}</ref>