ACPI - knowledge please...

In regards to my 6625, which I use primarily for sound production:

can anyone tell me about the importance of ACPI to my laptop (6625) - I know turning it off requires a full reinstall, not something to be taken lightly, but is it a prerequisite for some components...
I ask because RATTV3 seems to point to it providing a lot of dpc calls, thus bumping the DPC latency, and some music-specialist pc manufacturers are not at all keen on ACPI being enabled.
(yes, this is idle wondering... but it might lead to action in the future, if I feel it has a decent chance of effectiveness)

 

ACPI means Advanced Configuration and Power Interface. (Like APM that was more limited to control power management through the OS)
This puts the OS in control of the power management. Systems may be put into extremely low power consumption, and ofcourse ACPI makes sure it wakes up quickly.
ACPI does a lot more but I don't think that info will help you.

Only on very old systems we don't see ACPI but APM.
Maybe you can find some info here
http://forum.sysinternals.com/forum_posts.asp?TID=837

 

thanks for the quick reply, I will have a look at that.
I was just reading up on it a little - I realised I'd posted an ignorant sounding question asking for someone else to spoonfeed me knowledge, which is the sort of thing that irks me a little when others do it...
and I'm starting to remember what it was like sorting out IRQ conflicts on old computers. Although I suspect this (the ability to manually assign IRQ's, (plus the lack of power saving functions)) may be part of the reason others disable ACPI, I don't remember it particularly fondly.
... actually, I have read some of that before, perhaps this time I'll get to the end.
Anyway, further comments welcome.

 

well, it was recommended not to use ACPI with Win2000.
With XP, ACPI generally seems to be fairly well-considered. However, under ACPI IRQ's are auto-assigned, and cannot be manually assigned in the OS. I think this is why some people suggest using Standard PC instead of ACPI. For a laptop I imagine ACPI provides plenty of day-to-day advantages, and setup is probably a lot easier.
Vista generally seems less suitable for audio work, although the intention was, I think, that it would be capable of handling audio in a more stable way by allowing it higher system priority if necessary - not something I know much about, since I am leaving Vista alone for some time.

Could you tell me what sort of DPC latency you get please?
Do you wish the firewire was powered?


p.s. the more I read, the more it seems turning ACPI off is probably not a good solution.

 

Hi,

I wrote about ACPI but I mean AHCI
is not recommended for DAW ! sorry
I get low green bars between 30-100 us
with XP Home but not good with Vista!
I use RME Fireface 800 so I need external PSU

sorry for the confusion

regards S-EH

 

BIOS 015 was made to address DPC issues, you can read it in it's full glory here

Official release: http://forum.notebookreview.com/showthread.php?t=235817
The Push: http://forum.notebookreview.com/showthread.php?t=227434

 

hehe, yes it was... but it's not yet providing me with especially low latency, although certainly an improvement over 012.

Of course, this is an issue which has legion causes, but I know there are other 6625 users on the forum who experience similar problems, and none of the components I have has (to the best of my knowledge) an acknowledged problem with DPC calls.
I have been through Device Manager disabling devices (which lowers the average baseline DPC latency value), and I still get a fairly frequent bump of approx 1ms every 5ms. This is not from a fresh install with only minimal drivers, so it's quite possible that I simply haven't found the root cause of the problem, but it still occurs when everything none-vital is disabled in Device Manager (i.e. sound, video, networking, firewire, cardreader, expresscard, all disabled - touchpad, monitor, hard drive, usb ports enabled), and as mentioned in the first post RATTV3 (which can trace DPC calls) suggests that (if I'm reading it correctly) ACPI is responsible for a lot of these calls - which I haven't tried disabling, since it's not a component I can replace or have the option to disable. This makes me think that the new BIOS is not yet running as I would wish with regards to DPC latency (nor fan control).



S-E Hansson:
that's interesting, since it suggests that the problem is not BIOS related (which is quite possible), could you tell me a few more things about your system please?
- BIOS version
- do you have any devices disabled
- model of network card, and driver versions
- I presume NVidia 8600m gt - which drivers

When you say you get 30-100 us, do you get any regular spikes, or not?


In case of an answer, thanks
Matt

 

@stutter, I did the whole turning off ACPI thing with device manager (=>Standard PC) and ended up re-installing XP after that nightmare. A lot (like 50%) of the devices won't allow manual IRQ/DMA assignment so it's pretty much useless turning ACPI off - it's not like in the DOS days The system was in such a bad state that I didn't even try checking the DPC!

 

well, since this line of reasoning led to me trying disabling the batter, which seems to have worked in reducing the periodic high DPC calls, I'm happy enough.