# Re: \[PATCH v6 2/6\] PM / Runtime: introduce pm\_runtime\_set\_memalloc\_noio()

- From: Rafael J. Wysocki \<hidden\>
- Date: 2012-11-28 10:10:23 
- List: netdev
- Page: https://ratatoskr.run/netdev/2012/11/3964383
- Thread: https://ratatoskr.run/linux-pm/2012/11/3962556/t.md

```text
On Wednesday, November 28, 2012 05:47:18 PM Ming Lei wrote:
> On Wed, Nov 28, 2012 at 5:29 PM, Rafael J. Wysocki [ref] wrote:
> >
> > But it doesn't have to walk the children.  Moreover, with counters it only
> 
> Yeah, I got it, it is the advantage of counter, but with extra 'int'
> field introduced
> in 'struct device'.
> 
> > needs to walk the whole path if all devices in it need to be updated.  For
> > example, if you call pm_runtime_set_memalloc_noio(dev, true) for a device
> > whose parent's counter is greater than zero already, you don't need to
> > walk the path above the parent.
> 
> We still can do it with the flag only, pm_runtime_set_memalloc_noio(dev, true)
> can return immediately if one parent or the 'dev' flag is true.
> 
> But considered that the pm_runtime_set_memalloc_noio(dev, false) is only
> called in a very infrequent path(network/block device->remove()), looks the
> introduced cost isn't worthy of the obtained advantage.
> 
> So could you accept not introducing counter? and I will update with the
> above improvement you suggested.

Well, please see my other message I sent a while ago. :-)

Thanks,
Rafael


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
```