From: "Rafael J. Wysocki" <rjw@sisk.pl>
To: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Nathan Zimmer <nzimmer@sgi.com>,
linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
cpufreq@vger.kernel.org, Shawn Guo <shawn.guo@linaro.org>,
linaro-dev@lists.linaro.org
Subject: Re: [PATCH 0/2] cpufreq: cpufreq_driver_lock is hot on large systems
Date: Tue, 05 Feb 2013 11:03:13 +0100 [thread overview]
Message-ID: <3480441.gCEh0J5edK@vostro.rjw.lan> (raw)
In-Reply-To: <CAOh2x=n+ASeLpGHexxDvPGrN6ia+bLnNUNCb-covGDoABVk_wQ@mail.gmail.com>
On Tuesday, February 05, 2013 01:58:20 PM Viresh Kumar wrote:
> On Tue, Feb 5, 2013 at 6:37 AM, Rafael J. Wysocki <rjw@sisk.pl> wrote:
> > On Monday, February 04, 2013 04:45:11 PM Nathan Zimmer wrote:
> >> I am noticing the cpufreq_driver_lock is quite hot.
> >> On an idle 512 system perf shows me most of the system time is spent on this
> >> lock. This is quite signifigant as top shows 5% of time in system time.
> >> My solution was to first convert the lock to a rwlock and then to the rcu.
> >>
> >>
> >> Nathan Zimmer (2):
> >> cpufreq: Convert the cpufreq_driver_lock to a rwlock
> >> cpufreq: Convert the cpufreq_driver_lock to use the rcu
> >>
> >> drivers/cpufreq/cpufreq.c | 139 ++++++++++++++++++++++++++--------------------
> >> 1 file changed, 79 insertions(+), 60 deletions(-)
> >
> > I like these changes.
> >
> > Viresh, anyone, any comments?
>
> Hi Nathan/Rafael,
>
> Even i liked the basic idea behind the patchset, but didn't like the way it
> is divided into patches. For me, it is highly discouraged to undo something
> that you added in the same patchset. And you did exactly the same thing.
>
> Patch 2 is revert of 1 + rcu stuff.
>
> So, i would expect a single patch, i.e. merge of both patches + rebased
> on latest stuff.
I actually don't agree with that, becuase the Nathan's apprach shows the
reasoning that leads to the RCU introduction quite clearly. So if you
don't have technical problems with the patchset, I'm going to take it as is.
Thanks,
Rafael
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
next prev parent reply other threads:[~2013-02-05 9:57 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-04 22:45 Nathan Zimmer
2013-02-04 22:45 ` [PATCH 1/2] cpufreq: Convert the cpufreq_driver_lock to a rwlock Nathan Zimmer
2013-02-05 8:11 ` Viresh Kumar
2013-02-04 22:45 ` [PATCH 2/2] cpufreq: Convert the cpufreq_driver_lock to use the rcu Nathan Zimmer
2013-02-05 1:07 ` [PATCH 0/2] cpufreq: cpufreq_driver_lock is hot on large systems Rafael J. Wysocki
2013-02-05 8:28 ` Viresh Kumar
2013-02-05 10:03 ` Rafael J. Wysocki [this message]
2013-02-05 9:58 ` Viresh Kumar
2013-02-05 10:13 ` Rafael J. Wysocki
2013-02-05 14:58 ` Nathan Zimmer
2013-02-05 22:00 ` Rafael J. Wysocki
2013-02-06 2:04 ` [PATCH v2 linux-next " Nathan Zimmer
2013-02-06 2:04 ` [PATCH v2 linux-next 1/2] cpufreq: Convert the cpufreq_driver_lock to a rwlock Nathan Zimmer
2013-02-06 2:47 ` Viresh Kumar
2013-02-06 2:04 ` [PATCH v2 linux-next 2/2] cpufreq: Convert the cpufreq_driver_lock to use the rcu Nathan Zimmer
2013-02-06 2:52 ` Viresh Kumar
2013-02-06 8:51 ` Viresh Kumar
2013-02-06 13:00 ` Rafael J. Wysocki
2013-02-07 23:29 ` Rafael J. Wysocki
2013-02-11 17:13 ` Nathan Zimmer
2013-02-11 19:36 ` Rafael J. Wysocki
2013-02-12 4:03 ` Nathan Zimmer
2013-02-12 15:59 ` Paul E. McKenney
2013-02-13 13:20 ` Rafael J. Wysocki
2013-02-20 23:56 ` [PATCH v3 0/2] cpufreq: cpufreq_driver_lock is hot on large systems Nathan Zimmer
2013-02-20 23:56 ` [PATCH v3 1/2] cpufreq: Convert the cpufreq_driver_lock to a rwlock Nathan Zimmer
2013-02-20 23:56 ` [PATCH v3 2/2] cpufreq: Convert the cpufreq_driver_lock to use the rcu Nathan Zimmer
2013-02-21 5:50 ` Viresh Kumar
2013-02-21 17:49 ` Nathan Zimmer
2013-02-22 16:24 ` [PATCH v4 0/2] cpufreq: cpufreq_driver_lock is hot on large systems Nathan Zimmer
2013-02-22 16:24 ` [PATCH v4 1/2] cpufreq: Convert the cpufreq_driver_lock to a rwlock Nathan Zimmer
2013-02-23 3:57 ` Viresh Kumar
2013-02-22 16:24 ` [PATCH v4 2/2] cpufreq: Convert the cpufreq_driver_lock to use the rcu Nathan Zimmer
2013-02-23 3:39 ` Viresh Kumar
2013-02-25 20:07 ` Nathan Zimmer
2013-03-11 23:23 ` [PATCH v4 0/2] cpufreq: cpufreq_driver_lock is hot on large systems Rafael J. Wysocki
2013-03-13 20:50 ` Nathan Zimmer
2013-04-01 15:33 ` [PATCH v5] cpufreq: split the cpufreq_driver_lock and use the rcu (was cpufreq: cpufreq_driver_lock is hot on large systems) Nathan Zimmer
2013-04-01 16:28 ` Viresh Kumar
2013-04-01 17:17 ` Nathan Zimmer
2013-04-01 20:11 ` [PATCH v6 0/2] cpufreq: cpufreq_driver_lock is hot on large systems Nathan Zimmer
2013-04-01 20:11 ` [PATCH v6 1/2] cpufreq: split the cpufreq_driver_lock and use the rcu Nathan Zimmer
2013-04-02 5:05 ` Viresh Kumar
2013-04-02 14:55 ` Nathan Zimmer
2013-04-02 14:59 ` Viresh Kumar
2013-04-02 15:40 ` Nathan Zimmer
2013-04-02 15:52 ` Viresh Kumar
2013-04-02 22:57 ` Rafael J. Wysocki
2013-04-03 5:25 ` Viresh Kumar
2013-04-01 20:11 ` [PATCH v6 2/2] cpufreq: covert the cpufreq_data_lock to a spinlock Nathan Zimmer
2013-04-01 20:41 ` Rafael J. Wysocki
2013-04-02 0:56 ` Nathan Zimmer
2013-04-02 5:04 ` Viresh Kumar
2013-04-02 12:48 ` Rafael J. Wysocki
2013-04-02 14:58 ` Nathan Zimmer
Reply instructions:
You may reply publicly 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=3480441.gCEh0J5edK@vostro.rjw.lan \
--to=rjw@sisk.pl \
--cc=cpufreq@vger.kernel.org \
--cc=linaro-dev@lists.linaro.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pm@vger.kernel.org \
--cc=nzimmer@sgi.com \
--cc=shawn.guo@linaro.org \
--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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®