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The SD scheduler is heaven on many server loads

The SD scheduler is heaven on many server loads

Posted Apr 26, 2007 12:05 UTC (Thu) by hmh (subscriber, #3838)
Parent article: This week in the scheduling discussion

All I know is that SD seems to be all I ever wanted for regular (i.e. not HPC) servers.

The SD design never starves anything, ever. It has bound latency. CFS can't guarantee either as well as SD can. SD allows one to set the exact scheduling priority of everything and it is always respected, as there is no interactive renicing: it is very predictable.

And since one can also set the rr_interval (scheduling granularity) if the load is not latency sensitive, you can reduce its cost in context switches. It still has a few ways to go, but I hope to see in server -ck soon.

And SD is O(1), too... CFS isn't.

As someone said in LKML (maybe Con?), if the window managers were not so dumb and would renice things easily and intelligently, it might even be ideal for desktops. Oh well :-)


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The SD scheduler is heaven on many server loads

Posted Apr 26, 2007 12:11 UTC (Thu) by simlo (subscriber, #10866) [Link]

In practice there is not much difference between O(1) and O(log<number of tasks>). Especially since "1"=<number of priorities in the system>=140 and log<number of tasks><=log(2^64)=64.

The SD scheduler is heaven on many server loads

Posted Jun 4, 2007 9:00 UTC (Mon) by mingo (subscriber, #31122) [Link]

The SD design never starves anything, ever. It has bound latency. CFS can't guarantee either as well as SD can.

The CFS design does not starve anything ever either and has bound latency. I´m wondering why you think that ¨CFS can´t guarantee either as well¨.

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