[RFC 00/11]: powerKVM, release the compute power of secondary hwthread on host
kernelfans at gmail.com
kernelfans at gmail.com
Fri Oct 17 06:29:49 AEDT 2014
Nowadays, when running powerKVM(book3s, hv mode), we should make the secondary hwthread
offline. Which means that if we run misc tsks other than dedicated KVM (e.g mix java and KVM),
we will lose the compute power of the secondary hwthread on host env.
This series aim to make the powerpc adaptive to the misc tsks on host.
( This series is just a sketch, with some broken patch. Sorry to bring up it in a hurry,
I am afraid that I am on the wrong direction too far. So I hope I can get some advice and feedback
in advance. I will go on the work on the "place holder" patch if my idea is reasonable.
Please consider the code as the explaining of my idea.
-1.To enter guest, the primary hwthread schedule stopper func on the secondary to bring them into NAP mode.
The proto will be:
bring cpuX to a special state
signal flag and trapped
check for flag
set up guest env and ipi cpuX
-2.When exit to host, the secondary hardcode to jmp back to the stopper func, i.e back to host.
Drawbacks that I can think so far:
-1. increase the sched interval on secondary but the schduler do NOT know it.(can it cause problem?)
-2. lose some presice of hrtime on secondary hwthread for host.(To avoid the primary
has too small time slice, we need to impose a threshold，so we may lose the presice)
Any suggestion? Thanks!
Liu Ping Fan (11):
sched: introduce sys_cpumask in tsk to adapt asymmetric system
powerpc: kvm: ensure vcpu-thread run only on primary hwthread
powerpc: kvm: add interface to control kvm function on a core
powerpc: kvm: introduce a kthread on primary thread to anti tickless
sched: introduce stop_cpus_async() to schedule special tsk on cpu
powerpc: kvm: introduce online in paca to indicate whether cpu is
needed by host
powerpc: kvm: the stopper func to cease secondary hwthread
powerpc: kvm: add a flag in vcore to sync primary with secondry
powerpc: kvm: handle time base on secondary hwthread
powerpc: kvm: on_primary_thread() force the secondary threads into NAP
powerpc: kvm: Kconfig add an option for enabling secondary hwthread
arch/powerpc/include/asm/kvm_host.h | 6 ++++
arch/powerpc/include/asm/paca.h | 3 ++
arch/powerpc/kernel/asm-offsets.c | 6 ++++
arch/powerpc/kernel/smp.c | 3 ++
arch/powerpc/kernel/sysfs.c | 41 ++++++++++++++++++++++
arch/powerpc/kvm/Kconfig | 4 +++
arch/powerpc/kvm/book3s_hv.c | 39 +++++++++++++++++++++
arch/powerpc/kvm/book3s_hv_rmhandlers.S | 61 +++++++++++++++++++++++++++++++++
arch/powerpc/sysdev/xics/xics-common.c | 12 +++++++
include/linux/init_task.h | 1 +
include/linux/sched.h | 6 ++++
include/linux/stop_machine.h | 2 ++
kernel/sched/core.c | 10 ++++--
kernel/stop_machine.c | 25 +++++++++++---
14 files changed, 212 insertions(+), 7 deletions(-)
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