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Athlon XP-M cpu frequency scaling and Athcool
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Author:  stunted [ Mon Nov 14, 2005 7:36 pm ]
Post subject:  Athlon XP-M cpu frequency scaling and Athcool
Hi, got my system (below) working quite well, and now my recording patterns have stabilised [1] I'm probably only recording about 3 ~ 4 hours a day (this may go up when I switch to a decent cable provider) and after commflaging my CPU is idle, I'd like to run some "Power Now" style dynamic multiplier management and Athcool.

The problem is I can't run Athcool the whole time as it results in distorted sound, is there a way to run a script just before a recording starts and another after it ends?

How would I enable the Power Now stuff, there are some modules floating around and I'd really like this system to slow the processor down when idle like my Windows box which uses CrystalCPUID to clock at 400 Mhz when Idle.

[1] initially I was recording loads of stuff I wasn't watching, I still only watch about 2/3s of the stuff I record but it's *so* nice to have a buffer of add free TV waiting for me whenever I want to veg-out.
Author:  tjc [ Mon Nov 14, 2005 8:03 pm ]
Post subject: 
Do not be suprised if you suffer random and "mysterious" lock ups or crashes related to disk activity if you use athcool. The concept is nice but the technique used does not play well with some chipsets and/or BIOSes.
Author:  stunted [ Mon Nov 14, 2005 8:14 pm ]
Post subject: 
Yeah, I heard it wasn't perfect, but other that the sound going bad (fuzzy distorted and crackly) it seemed OK with my ECS K7S5A (SIS 735).

Oh and I tinkered with the PCI latency to no avail.

PS. I already underclock my Geforce 2 from 200 to 50MHz, this is fine for MPEG 4 playback and cools the passive heat-sync on the card from ouch thats too hot to touch for prolonged periods (about 60C) to mildly warm to the touch (about 40C). As far as I know, with my GPU, XvMC doesn't help with MPEG4 anyway and I don't do any MPEG2 playback at the moment so 50MHz is fine, (much lower and I get tearing around the interlace lines). At some point I'll sort out DVD playback, get a PVR 500 and probably get DVB-C, so I'll want the XvMC acceleration, my plan is to have a script run nvclock -r before playback starts and nvclock -m 50 -n 50 when it finishes, any idea's where I'd put them and even better if it would be possible to have it run conditionally depending on if the video to be played is MPEG2 and would be assisted by the added GPU speed or MPEG4 and wouldn't?

It would also be helpful for the HDTVers with Nvidia cards if it could have 3 states, like low power for menus & idle conditions, middle power for SDTV playback and full power for HDTV, this doesn't affect me as I don't think my GPU's up to HD anyway but my next one will be.

sh-3.00$ nvclock -r
Your nVidia Geforce 2 MX/MX400 has been restored to its original speeds
Memory speed: 167.043 MHz
Core speed: 199.656 MHz

sh-3.00$ nvclock -m 50 -n 50
nVidia Geforce 2 MX/MX400
Memory speed: 50.113 MHz
Core speed: 50.113 MHz
Author:  stunted [ Wed Nov 16, 2005 6:56 pm ]
Post subject: 
Just incase anyone's interested in this there is an interesting thread on the subject over on the Gentoo forums.
http://forums.gentoo.org/viewtopic-t-18 ... art-0.html

If you can't be bothered to read the thread the upshot is that the BIOS on a desktop motherboard doesn't contain the necessary PST tables that the list the valid voltage and multiplier settings for a given mobile CPU, also most desktop MBs can't change the core voltages anyway.

There is an apparently working patch for powernow-k7.c (the kernel module that does cpu frequency scaling for athlon XP-Ms) to stop it using the ACPI tables of CPU-modes, and instead use a user supplied table. There is also a suggestion that the ability to supply your own PST table may be included in the vanilla kernel at some point.

Hope this helps, I'm going to wait and see on powernow for the moment, I may have a go at patching when I have time.

I'd very much like a way to stop Athcool at the commencement of a recording and restart it at the end, any ideas?
Author:  Greg Frost [ Wed Nov 16, 2005 7:46 pm ]
Post subject: 
A hacky way to do it might be to use the messages written to the backend log file. I think that it outputs messages when starting and stopping playback.
Author:  stunted [ Tue Nov 22, 2005 1:30 am ]
Post subject: 
What, by having something monitor the logs or by finding and modifying the code that posts the log messages?

Would this same trick work for starting / stopping Athcool a just before the system starts and after it finishes recording?
Author:  Greg Frost [ Fri Nov 25, 2005 2:27 pm ]
Post subject: 
I was thinking of changing the backend startup script so that it tees the output through a script that parses it. In theory you should be able to do what you want as long as there is a recognisable string in the backend output whenever the trigger events that you are looking for happen. Its a horrible hack though that is liable to be broken if the output messages change when upgrading to a different KnoppMyth/Mythtv version.
Author:  red321 [ Sun Apr 02, 2006 9:23 am ]
Post subject: 
Is there any update on this old post ? I just changed out my 1600 Duron for a Geode 1750+, both on pcchips 848 motherboards. As the Geode is rated at 14W and the Duron is sonmthing like 55, I was hoping for a lot less heat and power.

Using an energy meter I only sem to be seeing a 20 watt saving,

[edit]
looking into it a bit more the Geode is 14W Typical 25 watt max, and the Duron is 48 Typical 57 max, so I guess I shoul donly expect 34 watts :-(

So I might not be far off, but I woul dlike to see how much more I can lose with powernow.
Author:  stunted [ Mon Apr 10, 2006 1:44 am ]
Post subject: 
I'm looking at getting a Geode CPU for my backend (probably a NX1500@6W version), how's yours going? Stable? where did you get it?

Also I don't think they variable clock like a mobile CPU, I think they just sit at their rated frequency (in your case 1.4GHz) not using much power.
Author:  red321 [ Tue Apr 18, 2006 6:41 am ]
Post subject: 
Sorry for the delay.

I am in the UK and got it from savacentre (was Watford electronics) It came bundles with a PC Chips 848a motherboard, with what looks like a specialised bios. I think the specialised BIOS is to support what is a mobile chip with the right voltages, and the whole thing was packaged as a unit, with the heatsink glued down.

Using cpuz and that sort of programme it is basicaly an Athlon Mobile chip, and does support all the things you would expect. (Variable frequency) I assuem that if you wound up the volts you could wind up the performance, but I was aiming the other way round. In windows on the same setup I can scale the frequency up and down from about 800 - 1400 but it doesnt actually make a worthwhile diffrence in the power usage, I think the real benifit comes in reducing the core voltage at the same time, which desktop motherboards seem incabable of doing under software control.

I havnt seen the 1500+ version for sale anywhere in the UK.
Author:  stunted [ Tue Apr 18, 2006 9:48 pm ]
Post subject: 
red321 wrote:
I am in the UK and got it from savacentre (was Watford electronics) It came bundles with a PC Chips 848a motherboard, with what looks like a specialised bios. I think the specialised BIOS is to support what is a mobile chip with the right voltages, and the whole thing was packaged as a unit, with the heatsink glued down.
I'm in Singapore, ASRock have just released a new BIOS for my K7VM3 that supports the Geode chips, if I can find one and they're not too expensive I'll give it a go.
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