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SubjectRe: [PATCH 3/3] vhost: apply cpumask and cgroup to vhost pollers
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On Thu, 2010-06-24 at 11:11 +0300, Michael S. Tsirkin wrote:
> On Sun, May 30, 2010 at 10:25:01PM +0200, Tejun Heo wrote:
> > Apply the cpumask and cgroup of the initializing task to the created
> > vhost poller.
> >
> > Based on Sridhar Samudrala's patch.
> >
> > Cc: Michael S. Tsirkin <mst@redhat.com>
> > Cc: Sridhar Samudrala <samudrala.sridhar@gmail.com>
>
>
> I wanted to apply this, but modpost fails:
> ERROR: "sched_setaffinity" [drivers/vhost/vhost_net.ko] undefined!
> ERROR: "sched_getaffinity" [drivers/vhost/vhost_net.ko] undefined!
>
> Did you try building as a module?

In my original implementation, i had these calls in workqueue.c.
Now that these are moved to vhost.c which can be built as a module,
these symbols need to be exported.
The following patch fixes the build issue with vhost as a module.

Signed-off-by: Sridhar Samudrala <sri@us.ibm.com>

diff --git a/kernel/sched.c b/kernel/sched.c
index 3c2a54f..15a0c6f 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4837,6 +4837,7 @@ out_put_task:
put_online_cpus();
return retval;
}
+EXPORT_SYMBOL_GPL(sched_setaffinity);

static int get_user_cpu_mask(unsigned long __user *user_mask_ptr,
unsigned len,
struct cpumask *new_mask)
@@ -4900,6 +4901,7 @@ out_unlock:

return retval;
}
+EXPORT_SYMBOL_GPL(sched_getaffinity);

/**
* sys_sched_getaffinity - get the cpu affinity of a process

> > ---
> > drivers/vhost/vhost.c | 36 +++++++++++++++++++++++++++++++-----
> > 1 file changed, 31 insertions(+), 5 deletions(-)
> >
> > Index: work/drivers/vhost/vhost.c
> > ===================================================================
> > --- work.orig/drivers/vhost/vhost.c
> > +++ work/drivers/vhost/vhost.c
> > @@ -23,6 +23,7 @@
> > #include <linux/highmem.h>
> > #include <linux/slab.h>
> > #include <linux/kthread.h>
> > +#include <linux/cgroup.h>
> >
> > #include <linux/net.h>
> > #include <linux/if_packet.h>
> > @@ -176,12 +177,30 @@ repeat:
> > long vhost_dev_init(struct vhost_dev *dev,
> > struct vhost_virtqueue *vqs, int nvqs)
> > {
> > - struct task_struct *poller;
> > - int i;
> > + struct task_struct *poller = NULL;
> > + cpumask_var_t mask;
> > + int i, ret = -ENOMEM;
> > +
> > + if (!alloc_cpumask_var(&mask, GFP_KERNEL))
> > + goto out;
> >
> > poller = kthread_create(vhost_poller, dev, "vhost-%d", current->pid);
> > - if (IS_ERR(poller))
> > - return PTR_ERR(poller);
> > + if (IS_ERR(poller)) {
> > + ret = PTR_ERR(poller);
> > + goto out;
> > + }
> > +
> > + ret = sched_getaffinity(current->pid, mask);
> > + if (ret)
> > + goto out;
> > +
> > + ret = sched_setaffinity(poller->pid, mask);
> > + if (ret)
> > + goto out;
> > +
> > + ret = cgroup_attach_task_current_cg(poller);
> > + if (ret)
> > + goto out;
> >
> > dev->vqs = vqs;
> > dev->nvqs = nvqs;
> > @@ -202,7 +221,14 @@ long vhost_dev_init(struct vhost_dev *de
> > vhost_poll_init(&dev->vqs[i].poll,
> > dev->vqs[i].handle_kick, POLLIN, dev);
> > }
> > - return 0;
> > +
> > + wake_up_process(poller); /* avoid contributing to loadavg */
> > + ret = 0;
> > +out:
> > + if (ret)
> > + kthread_stop(poller);
> > + free_cpumask_var(mask);
> > + return ret;
> > }
> >
> > /* Caller should have device mutex */
> --
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