From: John Ogness <john.ogness@linutronix.de>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
tglx@linutronix.de
Subject: Re: [PATCH] sched: Document that RT task priorities are 1…99
Date: Thu, 04 Apr 2019 09:45:53 +0200 [thread overview]
Message-ID: <87o95m8b7y.fsf@linutronix.de> (raw)
In-Reply-To: <87sguypz3z.fsf@linutronix.de> (John Ogness's message of "Wed, 03 Apr 2019 23:17:52 +0200")
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
next prev parent reply other threads:[~2019-04-04 7:46 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-03 21:08 [PATCH] sched: Document that RT task priorities are 1…99 Sebastian Andrzej Siewior
2019-04-03 21:17 ` John Ogness
2019-04-04 7:45 ` John Ogness [this message]
2019-04-16 8:13 ` [tip:sched/core] sched/core: Document that RT task priorities are 1...99 tip-bot for Sebastian Andrzej Siewior
2019-04-16 9:36 ` Peter Zijlstra
2019-04-16 9:47 ` Sebastian Andrzej Siewior
2019-04-16 11:22 ` Peter Zijlstra
2019-04-16 12:08 ` Sebastian Andrzej Siewior
2019-04-16 12:43 ` John Ogness
2019-06-17 12:24 ` [PATCH] sched: Document that RT task priorities are 1…99 Peter Zijlstra
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