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The long road to lazy preemption in the Linux CPU scheduler
(lwn.net)
218 points
chmaynard
| 5 comments |
19 Oct 24 07:29 UTC
|
HN request time: 0.205s
|
source
1.
weinzierl
◴[
19 Oct 24 09:11 UTC
]
No.
41886648
[source]
▶
>>41886256 (OP)
#
"Current kernels have four different modes that regulate when one task can be preempted in favor of another"
Is this about kernel tasks, user tasks or both?
replies(2):
>>41886784
#
>>41886832
#
ID:
GO
2.
GrayShade
◴[
19 Oct 24 09:44 UTC
]
No.
41886784
[source]
▶
>>41886648 (TP)
#
Kernel code, user-space code is always preemptible.
replies(1):
>>41887715
#
3.
◴[
19 Oct 24 09:55 UTC
]
No.
41886832
[source]
▶
>>41886648 (TP)
#
4.
fguerraz
◴[
19 Oct 24 13:40 UTC
]
No.
41887715
[source]
▶
>>41886784
#
Not true when the user-space thread has RT priority.
replies(1):
>>41887763
#
5.
temac
◴[
19 Oct 24 13:51 UTC
]
No.
41887763
{3}
[source]
▶
>>41887715
#
RT threads can be prempted by higher prio RT, and IIRC some kernel threads run at the highest prio. Plus you can be prempted by SMI, an hypervisor, etc
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