Re: Alternatives to /sys/kernel/debug/wakeup_sources

From: Greg Kroah-Hartman
Date: Wed Jun 19 2019 - 13:13:04 EST

On Wed, Jun 19, 2019 at 12:53:12PM -0400, Joel Fernandes wrote:
> > It is conceivable to have a "wakeup_sources" directory under
> > /sys/power/ and sysfs nodes for all wakeup sources in there.
> One of the "issues" with this is, now if you have say 100 wake up
> sources, with 10 entries each, then we're talking about a 1000 sysfs
> files. Each one has to be opened, and read individually. This adds
> overhead and it is more convenient to read from a single file. The
> problem is this single file is not ABI. So the question I guess is,
> how do we solve this in both an ABI friendly way while keeping the
> overhead low.

How much overhead? Have you measured it, reading from virtual files is
fast :)

And how often does this happen? Does it _need_ to happen?

Parsing files is also hard, and not for sysfs files, you can't have it
both ways.

So try it this way, and if there really is a performance issue, we can
then talk about it...


greg k-h