linux-kernel - Re: Generic battery interface

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20060728122508.GC4158@elf.ucw.cz>
Date:	Fri, 28 Jul 2006 14:25:08 +0200
From:	Pavel Machek <pavel@...e.cz>
To:	Vojtech Pavlik <vojtech@...e.cz>
Cc:	Shem Multinymous <multinymous@...il.com>,
	"Brown, Len" <len.brown@...el.com>,
	Matthew Garrett <mjg59@...f.ucam.org>,
	kernel list <linux-kernel@...r.kernel.org>,
	linux-thinkpad@...ux-thinkpad.org, linux-acpi@...r.kernel.org
Subject: Re: Generic battery interface

Hi!

> > >The applets that were doing it (yes, up to 100 times per second)
> > >corrected their ways pretty quickly, because some machines became
> > >unusable with the applet enabled.
> > 
> > Exactly -- and they've been working merrily ever since.
> > And if you don't want to trust applet developers, cache the latest
> > reads and refresh them only if X jiffies have passed.
> 
> The timer interrupt still has to happen every time their select() or
> sleep() expires, with the system having to wake up, even when nothing
> happened. Polling from userspace is bad.

I do not understand this. Any polling (in kernel or in userspace) will
wake the CPU, wasting power.

OTOH "high/low/very low" battery applet can reasonably query battery
every 5 minutes, while detailed, graphical thingie displaying the
current power consumption will probably poll every 10 seconds...
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/