From: Thomas Renninger <trenn@suse.de>
To: Saru Addep <saru.dpm@gmail.com>
Cc: cpufreq@lists.linux.org.uk
Subject: Re: Overall picture of cpufreq..
Date: Sun, 13 Jan 2008 23:54:34 +0100 [thread overview]
Message-ID: <1200264884.4157.16.camel@queen> (raw)
In-Reply-To: <9f79f7f50801111415w354dc91fwfeec98b16a00fb74@mail.gmail.com>
On Fri, 2008-01-11 at 14:15 -0800, Saru Addep wrote:
> Hi All,
...
> 2) What is the purpose of userspace governor.
You can set the frequency from userspace:
/sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed
(or similar) pops up when you switch to userspace governor.
The first dynamic cpufreq approaches were done in userspace. You have a
daemon checking every some 100 ms for the CPU load (/proc/stats) and
then decide whether to increase or decrease the freq.
The ondemand governor is doing that in kernel, but has the sideeffect of
not supporting HW (IIRC speedstep-lib, possibly longhaul, powernow-k7
(not sure) and other older ones) that takes too long for switching
frequencies. Then you would still need the userspace governor for
switching.
Thomas
next prev parent reply other threads:[~2008-01-13 22:54 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-01-11 22:15 Overall picture of cpufreq Saru Addep
2008-01-11 22:50 ` Leisner, Martin
2008-01-13 22:54 ` Thomas Renninger [this message]
2008-01-14 2:12 ` Saru Addep
2008-01-14 7:08 ` Tomasz Chmielewski
2008-01-14 7:51 ` Saru Addep
2008-01-14 9:51 ` Thomas Renninger
2008-01-14 10:16 ` Tomasz Chmielewski
2008-01-14 10:32 ` Thomas Renninger
2008-01-14 10:59 ` Tomasz Chmielewski
2008-01-14 19:13 ` Saru Addep
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