- Do timeslicing for SCHED_RR threads. At ~16Hz it's too slow but better
than nothing. XXX
- If a SCHED_OTHER thread has hogged the CPU for 1/8s without taking a
trip through mi_switch(), try to force a kernel preemption to give other
threads a chance.
we no longer need to guard against access from hardware interrupt handlers.
Additionally, if cloning a process with CLONE_SIGHAND, arrange to have the
child process share the parent's lock so that signal state may be kept in
sync. Partially addresses PR kern/37437.
mandatory. Remove the 4BSD run queue code. Effects:
- Pluggable scheduler is only responsible for co-ordinating timeshared jobs.
- All systems run with per-CPU run queues.
- 4BSD scheduler gets processor sets / affinity.
- 4BSD scheduler gets a significant peformance boost on some workloads.
Discussed on tech-kern@.
Add schedctl(8) - a program to control scheduling of processes and threads.
Notes:
- This is supported only by SCHED_M2;
- Migration of LWP mechanism will be revisited;
Proposed on: <tech-kern>. Reviewed by: <ad>.
tech-kern:
- Invert priority space so that zero is the lowest priority. Rearrange
number and type of priority levels into bands. Add new bands like
'kernel real time'.
- Ignore the priority level passed to tsleep. Compute priority for
sleep dynamically.
- For SCHED_4BSD, make priority adjustment per-LWP, not per-process.
on the original approach of SVR4 with some inspirations about balancing
and migration from Solaris. It implements per-CPU runqueues, provides a
real-time (RT) and time-sharing (TS) queues, ready to support a POSIX
real-time extensions, and also prepared for the support of CPU affinity.
The following lines in the kernel config enables the SCHED_M2:
no options SCHED_4BSD
options SCHED_M2
The scheduler seems to be stable. Further work will come soon.
http://mail-index.netbsd.org/tech-kern/2007/10/04/0001.htmlhttp://www.netbsd.org/~rmind/m2/mysql_bench_ro_4x_local.png
Thanks <ad> for the benchmarks!
from doc/BRANCHES:
idle lwp, and some changes depending on it.
1. separate context switching and thread scheduling.
(cf. gmcgarry_ctxsw)
2. implement idle lwp.
3. clean up related MD/MI interfaces.
4. make scheduler(s) modular.
