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 [thread overview]
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
next prev parent reply other threads:[~2019-06-19 17:07 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-05 0:23 Alternatives to /sys/kernel/debug/wakeup_sources 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
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