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path: root/drivers/cpuidle/cpuidle-haltpoll.c
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2020-04-08cpuidle-haltpoll: Fix small typoYihao Wu1-2/+2
Fix a spelling typo in cpuidle-haltpoll.c. Signed-off-by: Yihao Wu <wuyihao@linux.alibaba.com> [ rjw: Subject & changelog ] Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2020-03-14cpuidle: haltpoll: allow force loading on hosts without the REALTIME hintMaciej S. Szmigiero1-2/+10
Before commit 1328edca4a14 ("cpuidle-haltpoll: Enable kvm guest polling when dedicated physical CPUs are available") the cpuidle-haltpoll driver could also be used in scenarios when the host does not advertise the KVM_HINTS_REALTIME hint. While the behavior introduced by the aforementioned commit makes sense as the default there are cases where the old behavior is desired, for example, when other kernel changes triggered by presence by this hint are unwanted, for some workloads where the latency benefit from polling overweights the loss from idle CPU capacity that otherwise would be available, or just when running under older Qemu versions that lack this hint. Let's provide a typical "force" module parameter that allows restoring the old behavior. Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com> Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2019-10-22cpuidle: haltpoll: Take 'idle=' override into accountZhenzhong Duan1-0/+4
Currenly haltpoll isn't aware of the 'idle=' override, the priority is 'idle=poll' > haltpoll > 'idle=halt'. When 'idle=poll' is used, cpuidle driver is bypassed but current_driver in sys still shows 'haltpoll'. When 'idle=halt' is used, haltpoll takes precedence and makes 'idle=halt' have no effect. Add a check to prevent the haltpoll driver from loading if 'idle=' is present. Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com> Co-developed-by: Joao Martins <joao.m.martins@oracle.com> [ rjw: Subject ] Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2019-09-11cpuidle-haltpoll: Enable kvm guest polling when dedicated physical CPUs are ↵Wanpeng Li1-1/+2
available The downside of guest side polling is that polling is performed even with other runnable tasks in the host. However, even if poll in kvm can aware whether or not other runnable tasks in the same pCPU, it can still incur extra overhead in over-subscribe scenario. Now we can just enable guest polling when dedicated pCPUs are available. Acked-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Wanpeng Li <wanpengli@tencent.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2019-09-11cpuidle-haltpoll: do not set an owner to allow modunloadJoao Martins1-1/+0
cpuidle-haltpoll can be built as a module to allow optional late load. Given we are setting @owner to THIS_MODULE, cpuidle will attempt to grab a module reference every time a cpuidle_device is registered -- so essentially all online cpus get a reference. This prevents for the module to be unloaded later, which makes the module_exit callback entirely unused. Thus remove the @owner and allow module to be unloaded. Fixes: fa86ee90eb11 ("add cpuidle-haltpoll driver") Signed-off-by: Joao Martins <joao.m.martins@oracle.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2019-09-11cpuidle-haltpoll: return -ENODEV on modinit failureJoao Martins1-1/+1
When a user loads cpuidle-haltpoll on a non KVM guest the module will successfully load, even though idle driver registration didn't take place. We should instead return -ENODEV signaling the user that the driver can't be loaded, like other error paths in haltpoll_init(). An example of such error paths is when we return -EBUSY when attempting to register an idle driver when it had one already (e.g. intel_idle loads at boot and then we attempt to insert module cpuidle-haltpoll). Fixes: fa86ee90eb11 ("add cpuidle-haltpoll driver") Signed-off-by: Joao Martins <joao.m.martins@oracle.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2019-09-11cpuidle-haltpoll: set haltpoll as preferred governorJoao Martins1-0/+1
Right now, guest current governors have the following ratings: * ladder -> 10 * teo -> 19 * menu -> 20 * haltpoll -> 21 * ladder + nohz=off -> 25 haltpoll governor got introduced and it is now the default governor given its highest rating -- with ladder+nohz being the exception -- regardless of idle driver in the guest. An example of an undesirable case is x86 KVM guests with MWAIT which have intel_idle registered first, and consequently will have haltpoll be used as governor which would get limited to a poll state and state 1 and the other states wouldn't get used. To keep the previous defaults we decrease rating of governor to 9 (below current lowest rating) and thus rely on @governor switch on cpuidle_register_driver() to tie in haltpoll idle driver and governor together. Signed-off-by: Joao Martins <joao.m.martins@oracle.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2019-09-03cpuidle-haltpoll: vcpu hotplug supportJoao Martins1-5/+63
When cpus != maxcpus cpuidle-haltpoll will fail to register all vcpus past the online ones and thus fail to register the idle driver. This is because cpuidle_add_sysfs() will return with -ENODEV as a consequence from get_cpu_device() return no device for a non-existing CPU. Instead switch to cpuidle_register_driver() and manually register each of the present cpus through cpuhp_setup_state() callbacks and future ones that get onlined or offlined. This mimmics similar logic that intel_idle does. Fixes: fa86ee90eb11 ("add cpuidle-haltpoll driver") Signed-off-by: Joao Martins <joao.m.martins@oracle.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2019-07-30cpuidle-haltpoll: disable host side polling when kvm virtualizedMarcelo Tosatti1-1/+8
When performing guest side polling, it is not necessary to also perform host side polling. So disable host side polling, via the new MSR interface, when loading cpuidle-haltpoll driver. Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2019-07-30add cpuidle-haltpoll driverMarcelo Tosatti1-0/+68
Add a cpuidle driver that calls the architecture default_idle routine. To be used in conjunction with the haltpoll governor. Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>