€•S&      Œsphinx.addnodes”Œdocument”“”)”}”(Œ	rawsource”Œ ”Œchildren”]”(Œtranslations”ŒLanguagesNode”“”)”}”(hhh]”(h Œpending_xref”“”)”}”(hhh]”Œdocutils.nodes”ŒText”“”ŒChinese (Simplified)”…””}”Œparent”hsbaŒ
attributes”}”(Œids”]”Œclasses”]”Œnames”]”Œdupnames”]”Œbackrefs”]”Œ	refdomain”Œstd”Œreftype”Œdoc”Œ	reftarget”Œ)/translations/zh_CN/scheduler/sched-eevdf”Œmodname”NŒ	classname”NŒrefexplicit”ˆuŒtagname”hhhubh)”}”(hhh]”hŒChinese (Traditional)”…””}”hh2sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ)/translations/zh_TW/scheduler/sched-eevdf”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒItalian”…””}”hhFsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ)/translations/it_IT/scheduler/sched-eevdf”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒJapanese”…””}”hhZsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ)/translations/ja_JP/scheduler/sched-eevdf”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒKorean”…””}”hhnsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ)/translations/ko_KR/scheduler/sched-eevdf”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒPortuguese (Brazilian)”…””}”hh‚sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ)/translations/pt_BR/scheduler/sched-eevdf”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒSpanish”…””}”hh–sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ)/translations/sp_SP/scheduler/sched-eevdf”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubeh}”(h]”h ]”h"]”h$]”h&]”Œcurrent_language”ŒEnglish”uh1h
hhŒ	_document”hŒsource”NŒline”NubhŒsection”“”)”}”(hhh]”(hŒtitle”“”)”}”(hŒEEVDF Scheduler”h]”hŒEEVDF Scheduler”…””}”(hh¼h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hºhh·h²hh³ŒC/var/lib/git/docbuild/linux/Documentation/scheduler/sched-eevdf.rst”h´KubhŒ	paragraph”“”)”}”(hX¯  The "Earliest Eligible Virtual Deadline First" (EEVDF) was first introduced
in a scientific publication in 1995 [1]. The Linux kernel began
transitioning to EEVDF in version 6.6 (as a new option in 2024), moving
away from the earlier Completely Fair Scheduler (CFS) in favor of a version
of EEVDF proposed by Peter Zijlstra in 2023 [2-4]. More information
regarding CFS can be found in
Documentation/scheduler/sched-design-CFS.rst.”h]”hX³  The â€œEarliest Eligible Virtual Deadline Firstâ€ (EEVDF) was first introduced
in a scientific publication in 1995 [1]. The Linux kernel began
transitioning to EEVDF in version 6.6 (as a new option in 2024), moving
away from the earlier Completely Fair Scheduler (CFS) in favor of a version
of EEVDF proposed by Peter Zijlstra in 2023 [2-4]. More information
regarding CFS can be found in
Documentation/scheduler/sched-design-CFS.rst.”…””}”(hhÍh²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hËh³hÊh´Khh·h²hubhÌ)”}”(hX¸  Similarly to CFS, EEVDF aims to distribute CPU time equally among all
runnable tasks with the same priority. To do so, it assigns a virtual run
time to each task, creating a "lag" value that can be used to determine
whether a task has received its fair share of CPU time. In this way, a task
with a positive lag is owed CPU time, while a negative lag means the task
has exceeded its portion. EEVDF picks tasks with lag greater or equal to
zero and calculates a virtual deadline (VD) for each, selecting the task
with the earliest VD to execute next. It's important to note that this
allows latency-sensitive tasks with shorter time slices to be prioritized,
which helps with their responsiveness.”h]”hX¾  Similarly to CFS, EEVDF aims to distribute CPU time equally among all
runnable tasks with the same priority. To do so, it assigns a virtual run
time to each task, creating a â€œlagâ€ value that can be used to determine
whether a task has received its fair share of CPU time. In this way, a task
with a positive lag is owed CPU time, while a negative lag means the task
has exceeded its portion. EEVDF picks tasks with lag greater or equal to
zero and calculates a virtual deadline (VD) for each, selecting the task
with the earliest VD to execute next. Itâ€™s important to note that this
allows latency-sensitive tasks with shorter time slices to be prioritized,
which helps with their responsiveness.”…””}”(hhÛh²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hËh³hÊh´Khh·h²hubhÌ)”}”(hX˜  There are ongoing discussions on how to manage lag, especially for sleeping
tasks; but at the time of writing EEVDF uses a "decaying" mechanism based
on virtual run time (VRT). This prevents tasks from exploiting the system
by sleeping briefly to reset their negative lag: when a task sleeps, it
remains on the run queue but marked for "deferred dequeue," allowing its
lag to decay over VRT. Hence, long-sleeping tasks eventually have their lag
reset. Finally, tasks can preempt others if their VD is earlier, and tasks
can request specific time slices using the new sched_setattr() system call,
which further facilitates the job of latency-sensitive applications.”h]”hX   There are ongoing discussions on how to manage lag, especially for sleeping
tasks; but at the time of writing EEVDF uses a â€œdecayingâ€ mechanism based
on virtual run time (VRT). This prevents tasks from exploiting the system
by sleeping briefly to reset their negative lag: when a task sleeps, it
remains on the run queue but marked for â€œdeferred dequeue,â€ allowing its
lag to decay over VRT. Hence, long-sleeping tasks eventually have their lag
reset. Finally, tasks can preempt others if their VD is earlier, and tasks
can request specific time slices using the new sched_setattr() system call,
which further facilitates the job of latency-sensitive applications.”…””}”(hhéh²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hËh³hÊh´Khh·h²hubh¶)”}”(hhh]”(h»)”}”(hŒ
REFERENCES”h]”hŒ
REFERENCES”…””}”(hhúh²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hºhh÷h²hh³hÊh´K#ubhÌ)”}”(hŒk[1] https://citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&doi=805acf7726282721504c8f00575d91ebfd750564”h]”(hŒ[1] ”…””}”(hj  h²hh³Nh´NubhŒ	reference”“”)”}”(hŒghttps://citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&doi=805acf7726282721504c8f00575d91ebfd750564”h]”hŒghttps://citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&doi=805acf7726282721504c8f00575d91ebfd750564”…””}”(hj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”Œrefuri”j  uh1j  hj  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1hËh³hÊh´K%hh÷h²hubhÌ)”}”(hŒY[2] https://lore.kernel.org/lkml/a79014e6-ea83-b316-1e12-2ae056bda6fa@linux.vnet.ibm.com/”h]”(hŒ[2] ”…””}”(hj'  h²hh³Nh´Nubj  )”}”(hŒUhttps://lore.kernel.org/lkml/a79014e6-ea83-b316-1e12-2ae056bda6fa@linux.vnet.ibm.com/”h]”hŒUhttps://lore.kernel.org/lkml/a79014e6-ea83-b316-1e12-2ae056bda6fa@linux.vnet.ibm.com/”…””}”(hj/  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”Œrefuri”j1  uh1j  hj'  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1hËh³hÊh´K'hh÷h²hubhÌ)”}”(hŒ$[3] https://lwn.net/Articles/969062/”h]”(hŒ[3] ”…””}”(hjD  h²hh³Nh´Nubj  )”}”(hŒ https://lwn.net/Articles/969062/”h]”hŒ https://lwn.net/Articles/969062/”…””}”(hjL  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”Œrefuri”jN  uh1j  hjD  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1hËh³hÊh´K)hh÷h²hubhÌ)”}”(hŒ$[4] https://lwn.net/Articles/925371/”h]”(hŒ[4] ”…””}”(hja  h²hh³Nh´Nubj  )”}”(hŒ https://lwn.net/Articles/925371/”h]”hŒ https://lwn.net/Articles/925371/”…””}”(hji  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”Œrefuri”jk  uh1j  hja  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1hËh³hÊh´K+hh÷h²hubeh}”(h]”Œ
references”ah ]”h"]”Œ
references”ah$]”h&]”uh1hµhh·h²hh³hÊh´K#ubeh}”(h]”Œeevdf-scheduler”ah ]”h"]”Œeevdf scheduler”ah$]”h&]”uh1hµhhh²hh³hÊh´Kubeh}”(h]”h ]”h"]”h$]”h&]”Œsource”hÊuh1hŒcurrent_source”NŒcurrent_line”NŒsettings”Œdocutils.frontend”ŒValues”“”)”}”(hºNŒ	generator”NŒ	datestamp”NŒsource_link”NŒ
source_url”NŒtoc_backlinks”Œentry”Œfootnote_backlinks”KŒsectnum_xform”KŒstrip_comments”NŒstrip_elements_with_classes”NŒstrip_classes”NŒreport_level”KŒ
halt_level”KŒexit_status_level”KŒdebug”NŒwarning_stream”NŒ	traceback”ˆŒinput_encoding”Œ	utf-8-sig”Œinput_encoding_error_handler”Œstrict”Œoutput_encoding”Œutf-8”Œoutput_encoding_error_handler”j±  Œerror_encoding”Œutf-8”Œerror_encoding_error_handler”Œbackslashreplace”Œlanguage_code”Œen”Œrecord_dependencies”NŒconfig”NŒ	id_prefix”hŒauto_id_prefix”Œid”Œdump_settings”NŒdump_internals”NŒdump_transforms”NŒdump_pseudo_xml”NŒexpose_internals”NŒstrict_visitor”NŒ_disable_config”NŒ_source”hÊŒ_destination”NŒ_config_files”]”Œ7/var/lib/git/docbuild/linux/Documentation/docutils.conf”aŒfile_insertion_enabled”ˆŒraw_enabled”KŒline_length_limit”M'Œpep_references”NŒpep_base_url”Œhttps://peps.python.org/”Œpep_file_url_template”Œpep-%04d”Œrfc_references”NŒrfc_base_url”Œ&https://datatracker.ietf.org/doc/html/”Œ	tab_width”KŒtrim_footnote_reference_space”‰Œsyntax_highlight”Œlong”Œsmart_quotes”ˆŒsmartquotes_locales”]”Œcharacter_level_inline_markup”‰Œdoctitle_xform”‰Œdocinfo_xform”KŒsectsubtitle_xform”‰Œimage_loading”Œlink”Œembed_stylesheet”‰Œcloak_email_addresses”ˆŒsection_self_link”‰Œenv”NubŒreporter”NŒindirect_targets”]”Œsubstitution_defs”}”Œsubstitution_names”}”Œrefnames”}”Œrefids”}”Œnameids”}”(j‹  jˆ  jƒ  j€  uŒ	nametypes”}”(j‹  ‰jƒ  ‰uh}”(jˆ  h·j€  h÷uŒfootnote_refs”}”Œcitation_refs”}”Œautofootnotes”]”Œautofootnote_refs”]”Œsymbol_footnotes”]”Œsymbol_footnote_refs”]”Œ	footnotes”]”Œ	citations”]”Œautofootnote_start”KŒsymbol_footnote_start”K Œ
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