This commit adds a description of how expedited grace periods operate
during the mid-boot "dead zone", which starts when the scheduler spawns
the first kthread and ends when all of RCU's kthreads have been spawned.
In short, before mid-boot, synchronous grace periods can be a no-op.
After the end of mid-boot, workqueues may be used. During mid-boot,
the requesting task drivees the expedited grace period.
For more detail, see https://lwn.net/Articles/716148/.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit adds design documentation for expedited grace periods.
This documentation is in HTML rather than the new documentation
format because (1) I have prototype documentation already in HTML,
and (2) Attempting to learn the new documentation format while
creating the design documentation seems likely to result in neither
happening in a timely fashion.
Once the design documentation is complete, we can start a conversion effort.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Paul E. McKenney