Linux-PM Archive on lore.kernel.org
 help / color / Atom feed
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Joel Fernandes <joelaf@google.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>,
	Tri Vo <trong@android.com>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Sandeep Patil <sspatil@android.com>,
	Viresh Kumar <viresh.kumar@linaro.org>,
	Hridya Valsaraju <hridya@google.com>,
	Linux PM <linux-pm@vger.kernel.org>,
	"Cc: Android Kernel" <kernel-team@android.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Alexei Starovoitov <ast@kernel.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Alexei Starovoitov <ast@fb.com>
Subject: Re: Alternatives to /sys/kernel/debug/wakeup_sources
Date: Wed, 19 Jun 2019 19:07:50 +0200
Message-ID: <20190619170750.GB10107@kroah.com> (raw)
In-Reply-To: <CAJWu+oqSgcBVhDY7CjWpNQrK=XiKAb5S-YSp=6-UM--UFmKvGQ@mail.gmail.com>

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...

thanks,

greg k-h

  reply index

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-05  0:23 Tri Vo
2019-06-11 17:31 ` Tri Vo
2019-06-18 20:17   ` Sandeep Patil
2019-06-18 21:23     ` Rafael J. Wysocki
2019-06-18 23:15       ` Tri Vo
2019-06-18 23:52         ` Joel Fernandes
2019-06-19  8:35           ` Rafael J. Wysocki
2019-06-19 10:33             ` Joel Fernandes
2019-06-19 16:51             ` Sandeep Patil
2019-06-19 16:53             ` Joel Fernandes
2019-06-19 17:07               ` Greg Kroah-Hartman [this message]
2019-06-19 18:01                 ` Joel Fernandes
2019-06-19 18:31                   ` Tri Vo
2019-06-19 18:35                   ` Greg Kroah-Hartman
2019-06-19 18:55                     ` Joel Fernandes
     [not found]                       ` <CAGETcx-ZZRc_jtBws2cFTe1wjiWeBowdqfqOhcCJV_7AUyBEVw@mail.gmail.com>
2019-06-19 20:09                         ` Joel Fernandes
2019-06-19 20:40                           ` Saravana Kannan
2019-06-19 20:52                             ` Joel Fernandes
2019-06-24  1:48             ` Tri Vo
2019-06-24  7:36               ` Greg Kroah-Hartman
2019-06-24 12:27                 ` Joel Fernandes
2019-06-24 21:55                   ` Rafael J. Wysocki
2019-06-24 22:14                     ` Tri Vo

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190619170750.GB10107@kroah.com \
    --to=gregkh@linuxfoundation.org \
    --cc=ast@fb.com \
    --cc=ast@kernel.org \
    --cc=hridya@google.com \
    --cc=joelaf@google.com \
    --cc=kernel-team@android.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-pm@vger.kernel.org \
    --cc=rafael@kernel.org \
    --cc=rjw@rjwysocki.net \
    --cc=rostedt@goodmis.org \
    --cc=sspatil@android.com \
    --cc=trong@android.com \
    --cc=viresh.kumar@linaro.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-PM Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-pm/0 linux-pm/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-pm linux-pm/ https://lore.kernel.org/linux-pm \
		linux-pm@vger.kernel.org linux-pm@archiver.kernel.org
	public-inbox-index linux-pm


Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-pm


AGPL code for this site: git clone https://public-inbox.org/ public-inbox