Messages in this thread | | | From | John Ogness <> | Subject | Re: [PATCH] sched: Document that RT task priorities are 1…99 | Date | Thu, 04 Apr 2019 09:45:53 +0200 |
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On 2019-04-03, John Ogness <john.ogness@linutronix.de> wrote: > IMHO it is a bit crazy that userspace RT prio 99 maps to kernel prio > 0. This leaves a hole at kernel prio 99. Wouldn't it be better just to > map userspace RT prio 1-99 to kernel prio 99-1?
FWIW, the current mapping:
userspace kernel --------- ------ rt 1...99 98...0 nice -20...+19 100...139
has been in place since the introduction of Ingo's scalable scheduler:
Author: linus1 <torvalds@athlon.transmeta.com> Date: Sun Dec 16 12:00:00 2001 -0800
v2.5.1.9 -> v2.5.1.10 - Kai Germaschewski: ISDN updates - Al Viro: start moving buffer cache indexing to "struct - block_device *" - Greg KH: USB update - Russell King: fix up some ARM merge issues - Ingo Molnar: scalable scheduler
With that commit, the then separate nice and rt_priority task_struct fields were combined to the new prio field, and thus the mapping was born.
John Ogness
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