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SubjectRe: [PATCH] init,cpuset: fix initialize order
On Wed, Mar 25, 2009 at 02:51:39PM +0100, Frederic Weisbecker wrote:
> On Wed, Mar 25, 2009 at 05:06:30PM +0800, Lai Jiangshan wrote:
> >
> > (After these two fixes applied:
> > [PATCH 1/2] trace_stat: keep original order
> > [PATCH 2/2] trace_workqueues: fix empty line's output
> > )
> > When I read /debugfs/tracing/trace_stat/workqueues,
> > and the I got this:
> >
> > # CPU INSERTED EXECUTED NAME
> > # | | | |
> >
> > 0 0 0 cpuset
> > 0 285 285 events/0
> > 0 2 2 work_on_cpu/0
> > 0 1115 1115 khelper
> > 0 325 325 kblockd/0
> > 0 0 0 kacpid
> > 0 0 0 kacpi_notify
> > 0 0 0 ata/0
> > 0 0 0 ata_aux
> > 0 0 0 ksuspend_usbd
> > 0 0 0 aio/0
> > 0 0 0 nfsiod
> > 0 0 0 kpsmoused
> > 0 0 0 kstriped
> > 0 0 0 kondemand/0
> > 0 1 1 hid_compat
> > 0 0 0 rpciod/0
> >
> > 1 64 64 events/1
> > 1 2 2 work_on_cpu/1
> > 1 5 5 kblockd/1
> > 1 0 0 ata/1
> > 1 0 0 aio/1
> > 1 0 0 kondemand/1
> > 1 0 0 rpciod/1
> >
> > I found "cpuset" is at the earliest.
> > ---------
> >
> > Subject: [PATCH] init,cpuset: fix initialize order
> >
> > Impact: cpuset_wq should be initialized after init_workqueues()
> >
> > I found a create_singlethread_workqueue() is earlier than
> > init_workqueues():
> >
> > kernel_init()
> > ->cpuset_init_smp()
> > ->create_singlethread_workqueue()
> > ->do_basic_setup()
> > ->init_workqueues()
> >
> > I think it's better that create_singlethread_workqueue() is called
> > after workqueue subsystem has been initialized.
> >
> > Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
> > ---
>
>
> Indeed it seems to be a bug.
> If init_workqueues() have not been called:
>
> - cpu_singlethread_map = NULL
> - singlethread_cpu = 0
>
> create_workqueue_thread() will be called with cpu = 0 and
> then: kthread_create(worker_thread, cwq, fmt, wq->name, cpu = 0);
>
> Meaning that cpuset is only bound to the first cpu.
>
> Frederic.
>


Ah no, kthread_bind is called just after with -1 for the cpu.

Frederic.


> > diff --git a/init/main.c b/init/main.c
> > index 1ce6931..91d5047 100644
> > --- a/init/main.c
> > +++ b/init/main.c
> > @@ -773,6 +773,7 @@ static void __init do_basic_setup(void)
> > {
> > rcu_init_sched(); /* needed by module_init stage. */
> > init_workqueues();
> > + cpuset_init_smp();
> > usermodehelper_init();
> > driver_init();
> > init_irq_proc();
> > @@ -869,8 +870,6 @@ static int __init kernel_init(void * unused)
> > smp_init();
> > sched_init_smp();
> >
> > - cpuset_init_smp();
> > -
> > do_basic_setup();
> >
> > /*
> >
> >
>



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