[libvirt] Question / Bug: "IO mon_iothread" not affected by "<iothreadsched scheduler=.."

gima+libvir-list at iki.fi gima+libvir-list at iki.fi
Sun Dec 29 22:26:40 UTC 2019


# Question / Bug

For "<iothreads>1</iothreads>", QEMU creates two threads by name of
"IO mon_iothread"and
"IO iothread1"

Both are affected by "<iothreadpin iothread='1' cpuset='5'/>" (pinned to 
specified CPU), but only "IO iothread1" is affected by "<iothreadsched 
iothread='1' cpuset='5'/>".

I believe this is to be a bug, whereas both threads should be affected, 
and be set to be ruled by the specified iothread scheduler. Am I correct 
and is this a bug, or am I missing something?


# What does this matter / How does this manifest a problem?

This manifests in case there is 1 iothread, and both iothread and 
emulator are pinned to the same cpu and set to use fifo or rr as their 
scheduler. In this configuration, QEMU does not start correctly and 
"stalls" until I change the scheduler of "IO mon_iothread" to rr or fifo 
(respectively).

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