On Wed, Nov 12, 2014 at 5:22 PM, Srikar Dronamraju
<srikar@xxxxxxxxxxxxxxxxxx> wrote:
> * kernelfans@xxxxxxxxx <kernelfans@xxxxxxxxx> [2014-10-16 15:29:50]:
>
>> Some system such as powerpc, some tsk (vcpu thread) can only run on
>> the dedicated cpu. Since we adapt some asymmetric method to monitor the
>> whole physical cpu. (powerKVM only allows the primary hwthread to
>> set up runtime env for the secondary when entering guest).
>>
>> Nowadays, powerKVM run with all the secondary hwthread offline to ensure
>> the vcpu threads only run on the primary thread. But we plan to keep all
>> cpus online when running powerKVM to give more power when switching back
>> to host, so introduce sys_allowed cpumask to reflect the cpuset which
>> the vcpu thread can run on.
>>
>> Signed-off-by: Liu Ping Fan <pingfank@xxxxxxxxxxxxxxxxxx>
>> ---
>> include/linux/init_task.h | 1 +
>> include/linux/sched.h | 6 ++++++
>> kernel/sched/core.c | 10 ++++++++--
>> 3 files changed, 15 insertions(+), 2 deletions(-)
>>
>> diff --git a/include/linux/init_task.h b/include/linux/init_task.h
>> index 2bb4c4f3..c56f69e 100644
>> --- a/include/linux/init_task.h
>> +++ b/include/linux/init_task.h
>> @@ -172,6 +172,7 @@ extern struct task_group root_task_group;
>> .normal_prio = MAX_PRIO-20, \
>> .policy = SCHED_NORMAL, \
>> .cpus_allowed = CPU_MASK_ALL, \
>> + .sys_allowed = CPU_MASK_ALL, \
>
> Do we really need another mask, cant we just use cpus_allowed itself.
>
I think it is not easy to cast two request: chip inherit and user's
configuration onto one mask.
>> .nr_cpus_allowed= NR_CPUS, \
>> .mm = NULL, \
>> .active_mm = &init_mm, \
>> diff --git a/include/linux/sched.h b/include/linux/sched.h
>> index 5c2c885..ce429f3 100644
>> --- a/include/linux/sched.h
>> +++ b/include/linux/sched.h
>> @@ -1260,7 +1260,10 @@ struct task_struct {
>>
>> unsigned int policy;
>> int nr_cpus_allowed;
>> + /* Anded user and sys_allowed */
>> cpumask_t cpus_allowed;
>> + /* due to the feature of asymmetric, some tsk can only run on such cpu */
>> + cpumask_t sys_allowed;
>>
>> #ifdef CONFIG_PREEMPT_RCU
>> int rcu_read_lock_nesting;
>> @@ -2030,6 +2033,9 @@ static inline void tsk_restore_flags(struct task_struct *task,
>> }
>>
>> #ifdef CONFIG_SMP
>> +extern void set_cpus_sys_allowed(struct task_struct *p,
>> + const struct cpumask *new_mask);
>> +
>> extern void do_set_cpus_allowed(struct task_struct *p,
>> const struct cpumask *new_mask);
>>
>> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
>> index ec1a286..2cd1ae3 100644
>> --- a/kernel/sched/core.c
>> +++ b/kernel/sched/core.c
>> @@ -4596,13 +4596,19 @@ void init_idle(struct task_struct *idle, int cpu)
>> }
>>
>> #ifdef CONFIG_SMP
>> +void set_cpus_sys_allowed(struct task_struct *p,
>> + const struct cpumask *new_mask)
>> +{
>> + cpumask_copy(&p->sys_allowed, new_mask);
>> +}
>> +
>
> This function doesnt seem to be used anywhere... Not sure why it is
> introduced
>
Not layered the patches well :( It is used later in the series.
Thx,
Fan
>> void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
>> {
>> if (p->sched_class && p->sched_class->set_cpus_allowed)
>> p->sched_class->set_cpus_allowed(p, new_mask);
>>
>> - cpumask_copy(&p->cpus_allowed, new_mask);
>> - p->nr_cpus_allowed = cpumask_weight(new_mask);
>> + cpumask_and(&p->cpus_allowed, &p->sys_allowed, new_mask);
>> + p->nr_cpus_allowed = cpumask_weight(&p->cpus_allowed);
>> }
>>
>> /*
>> --
>> 1.8.3.1
>>
>>
>
> --
> Thanks and Regards
> Srikar Dronamraju
>
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