CVSROOT: /cvs
Module name: src
Changes by: [email protected] 2020/02/25 09:55:33
Modified files:
sys/kern : init_main.c kern_smr.c
sys/sys : smr.h
Log message:
Start the SMR thread when all CPUs are ready for scheduling. This
prevents the appearance of a "smr: dispatch took N seconds" message
during boot when there is an early smr_call(). Such a call can happen
with mfii(4). The initial dispatch cannot make progress until
smr_grace_wait() can visit all CPUs.
This fix is essentially a hack. It makes use of the fact that there
is no hard guarantee on how quickly the callback of smr_call() gets
invoked. It is assumed that the SMR call backlog does not grow large
during boot.
An alternative fix is to make smr_grace_wait() skip secondary CPUs
until they have been started. However, this could break if the spinup
logic of secondary CPUs was changed.
Delayed SMR dispatch reported and fix tested by Hrvoje Popovski
Discussed with and OK kettenis@, claudio@
