From mboxrd@z Thu Jan 1 00:00:00 1970 From: John Haxby Subject: Re: Xen power management default governor Date: Tue, 12 Jan 2010 10:36:38 +0000 Message-ID: <4B4C50B6.8060600@oracle.com> References: <05B5EEEB4701429FBB815E35A9AC9A54@china.huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <05B5EEEB4701429FBB815E35A9AC9A54@china.huawei.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Kaushik Barde Cc: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org On 11/01/10 23:36, Kaushik Barde wrote: > I believe, userspace governor gives better application control for instance, > controlling P-states through existing userspace frequency scaling daemons. > > Just easier to set one's own power management policy. > > -Kaushik > Yes, but that's true, but that doesn't explain why userspace is the default, especially as there doesn't seem to be any userspace governor in the distribution and anyway, the userspace default was abandoned in the mainline Linux kernel because ondemand works rather better. On most machines, "userspace" with no running governor daemon is the same as "performance". However, on some BIOS revisions of some hardware, "userspace" is the same as "powersave" and this basically makes it look as though the system is running rather slower than you would expect. So while userspace might be good for people who have clear cut ideas of what they think the policy for scaling should be, it's not good for everyone else and, in fact, it might lead people to believe that performance is actually rather poor. > -----Original Message----- > From: xen-devel-bounces@lists.xensource.com > [mailto:xen-devel-bounces@lists.xensource.com] On Behalf Of John Haxby > Sent: Monday, January 11, 2010 4:51 AM > To: xen-devel@lists.xensource.com > Subject: [Xen-devel] Xen power management default governor > > > Can anyone tell me why the default governor for power management is > "userspace"? If there any reason why it shouldn't be "ondemand"? > > And is there a userspace governor daemon that I've overlooked? > > jch > > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xensource.com > http://lists.xensource.com/xen-devel > >