On Mon, Jan 21, 2013 at 11:35:51PM +0100, Rafael J. Wysocki wrote: > On Monday, January 21, 2013 12:53:57 PM Greg Kroah-Hartman wrote: > > On Mon, Jan 21, 2013 at 02:05:47PM +0100, Rafael J. Wysocki wrote: > > > From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> > > > > > > Since ACPI power resources are going to be used more extensively on > > > new hardware platforms, it becomes necessary for user space (powertop > > > in particular) to observe some properties of those resources for > > > diagnostics purposes. > > > > > > For this reason, export the reference counts of ACPI power resources > > > to user space by adding a new reference_count attribute to the sysfs > > > directory representing each power resource. The value read from > > > that attribute represents the number of devices using the power > > > resource at the given time. If that value is 0, it meas that the > > > power resource is not used and therefore it has been turned off. > > > > Why does userspace need to know a reference count? Is it so that if it > > is not 0, it can work to try to lower it to 0? Or something else? > > Yes, this information is needed to say if (1) the power resource is in use > and (2) how many users there are at the moment, so that we can go and look > if it really has to be in use. > > Perhaps I can just expose the "in use"/"not in use" information. I don't > think it will be much less convenient, because we should scan all of the > possible users anyway in case they are coming and going frequently. > > So should I do that and rename the attribute to "resource_in_use" (or something > similar)? That makes a bit more sense to do, thanks. greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
