1 Topic by Timur Born (edited by Timur 2009-01-23 02:27:45)

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Topic: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

Here is a small HOWTO for getting the lowest possible DPC latencies (<100 us) on bootcamped Macbooks Pro (late 2008):

Disclaimer: I did all tests on my late 2008 Macbook Pro Unibody 2.8 GHz model with NVidia chipset and graphic. Most of the following suggestions should apply to standard Macbook models and likely older generation as well.

First of all Intel Speedstep leads to dropouts and higher DPC latencies on small load! Unfortunately all tools that are supposed to manually switch Speedstep off don't seem to run on the late Macbooks (Pro) while on OS X you can use "Coolbook".

Your only way to make sure your processor is clocked high enough and not dynamically switching is to put up a constant load (like running your DAW pretty hot or running Prime95 at "Idle/Lowest" process Priority in the background). I will keep investigating if I can find a tool to switch Speedstep off.

Most importantly (to get rid of really bad DPC latency spikes):

Kill the process "KBDMGR.EXE"!

That's Apple's driver for controlling brightness and keyboard lighting via the function keys and setting tap options for the trackpad. It seems to have broken multithreading! You can also the CPU affinity of KBDMGR.EXE to CPU1 (not CPU0!) which will help decreasing DPC Latencies alot, but there will still be Audio dropouts.

Here's a small toolkit I put together that allows you to conviniently enable/disable Apple's "Boot Camp" tray application (KBDMGR.EXE) via an icon link and/or keyboard shortcut. Optionally it will switch the function of the F-Keys automatically for you depending on whether Boot Camp is loaded or not.

Furthermore it automatically turns Boot Camp's CPU priority to "Idle" and CPU affinity to CPU1 in order to turn down the bug induced DPC Latencies and prevent dropouts with Windows sounds and Media Player playback. Professional Audio users will find that only turning off Boot Camp will allow low audio latency usage.  Installation instructions are included in the README.TXT for your convinience. wink

Boot CampED - Download Page

Turn off the Broadcom 802.11N WLAN driver via Device-Manager or update to the latest drivers via Microsoft Update Catalog.

Like on OS X the Airport module can lead to audio dropouts. The DPC Latencies produced by the Broadcom driver are less regular than the KBDMGR thing, alot higher in value. Best thing is to try for your own needs.

Update:Meanwhile a new Broadcom drivers was published via Microsoft's Update Catalog named "Broadcom - Network - Broadcom 4322AG 802.11a/b/g/draft-n Wi-Fi Adapter " (4322 is the chip used). This one comes with both low DPC latencies and finally the ability to use the full rate upto 300 mbit/s. Go get it! For safety you might still want to turn WLAN off during critical audio work though.

Change the graphic-card driver to "Standard VGA Driver" via Device-Manager or use RIVATUNER to enforce a fixed clock-rate and performance mode.

Update:The dynamic clock-rate switching happening with NVidia drivers in order to save power and keep temperatures low leads to extreme DPC spikes for each switch and constantly high DPC latencies when it settles in low performance 2D mode. RIVATUNER's "Enforce Performance Mode" option can be used to set the card to a fixed clock-rate. I recommend using "Low Power 3D" for audio work.

User of XP might think that they don't need this, but be aware that on XP the NVidia driver keeps running at highest clock-rates in "Performance 3D Mode" all the time. Via RIVATUNER you can switch to "Low Power 3D".

Turn off the ACPI compliant Battery driver via Device-Manager

This driver polls the battery for its current load status and produces a small, single, short spike exactly every 15 seconds. In my own tests I found that it doesn't seem to affect low latency audio performance. Furthermore turning it off will remove monitoring of your current battery status. But if you are running on power-chord anyway and want to make absolutely sure you can turn it off.

All other devices don't add much if anything to DPC latencies, but can savely be turned off if you don't need them (like Nvidia LAN, Bluetooth, Onboard High Definition Audio).

Attention: Removing the Battery while the power chord is connected results in permanently reduced CPU clock (downto the lowest clock setting possible). According to Apple this is done to prevent overloading the power-supply during heavy load as it needs the assistance of the battery from time to time.

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Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

modified several parts of the original posting, especially the paragraph about the graphic-card drivers

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Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

hey timur,

have you realy bought a mac to have windows installed on that machine? fryingpan (... ein bisschen spa? mu? sein, dann ist die welt voll sonnenschein ... oder wie war das nochmal?)

4 Reply by Timur Born (edited by Timur 2008-12-10 15:41:49)

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Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

Beside Ableton Live and now Logic I own Sonar (Windows only), so I'm using both OSes at least until I know how to deal with OS X inside out. :-)

I'm also not happy with OS X performance yet, my Kore 1 USB interface seems to performs better on Windows and the Fireface 400 connected to a TI based Expresscard hardly manages to perform 5% better than my old Desktop PC (A64 X2 @ 2800 GHz with DDR1 RAM).

Unfortunately I just found out that for low latency performance you need to kill the KBDMGR.EXE process completely!

Even when there is no increase in DPC and IRQ cycles and near to no CPU load happening from KBDMGR it still interrupts the audio of my Kore 1. Interestingly the buzzing/zipping noises that are happening sound very much like the noise I get on OS X (eventhough at higher load). So something about that Keyboard/Screen lighting control is fishy.

5 Reply by Dalibor Loncar (edited by Dalibor Loncar 2008-12-12 11:25:40)

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Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

you really have to have a "tweaking-fetish".

what?s wrong with my vostro? :censored

[img align=C]http://www.bilderhosting.info/137598.jpg[/img]

i did it the other way round (and yes, i have an os x license and i know that i am not allowed to install it on non apple hw, but i am still annoyed that apple bought emagic in 2002 and stopped the production of logic for pc -> i have invested a lot of money in both emagic hard- and software from the beginning of the 90s until 2002). now I can upgrade from 5.5.1 pc to logic 8 (to be honest I?ve upgraded to Logic Pro 6 in 2003 because there was a possibilty to activate all the plug-ins of logic 6 for the use in 5.5.1 for pc).

btw, my dellintosh works fine! the only thing is i get clicks and pops if the audio buffer of my interface is set below 256 samples with a cpu workload of about 80%(but maybe my interface would similarly behave on a "real" one, i should check that). for mixing in logic only i don?t need lower latencies.

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Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

I tested the Bluetooth connection via a Mighy Mouse Wireless and it doesn't seem to have any considerable negative impact on DPC latencies. Bluetooth is internally connected via USB by the way.

WLAN (Broadcom) still needs to be turned off for serious audio applications. While I was able to get really nice and low DPC latencies with WLAN being active it gets worse as soon as you don't actively use the connection anymore. Fiddling with the various energy-saving settings in the driver didn't have much of an impact, nor had the tool "Vista Anti-Lag".

So swith WLAN off and keep Bluetooth running (if you need it). fryingpan

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Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

Thanks Timur,
I'm reading your posts with interest. I have a macbook pro and I'm trying to decide whether to keep it. It's gotta run xp well.

Question for you, why did you load vista and not xp pro?

Randy

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8 Reply by Timur Born (edited by Timur 2008-12-26 22:38:41)

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Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

I also checked XP meanwhile and will write an extensive report about it as soon as I have time. In short some settings will differ on XP compared to Vista, but performance is about the same.

Vista is my favorite, because it's simply the better OS compared to XP and I am owning a licence of Vista Ultimate already. (Plus I can do DirectX 10 gaming with the inbuild 9600M GT lol).

9 Reply by Timur Born (edited by Timur 2008-12-28 18:03:25)

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Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

Robert Randolph;3729642 wrote:

Note: Nvidia powermizer should be turned off as well. It has great effect on DPC latency.

On XP (in contrast to Vista) you can access PowerMizer settings, but they don't have any effect on the late 2008 MBP, neither DPC wise nor battery/power wise.

Furthermore the NVidia driver produces no relevant DPC/load spikes on XP, but it's a good idea to deactivate "Cursor Acceleration" (set the Troubleshooting setting one tick down). The standard VGA driver on XP (only accessible by uninstalling the NVidia driver) shows lousy performance and should be avoided altogether.

It's also not mandatory to deactivate the ACPI Battery service on XP, because it produces smaller spikes in irregular intervals only.

All in all the lowest DPC latencies I could measure on XP are downto 2 us, but with the tweaks listed in this thread performance of Vista is roughly on par with XP if not even slightly better on my MBP 2.8 GHz.

10 Reply by Timur Born (edited by Timur 2008-12-28 10:02:32)

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Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

Changed the original post to emphasize that KBDMGR.EXE needs to be killed in order to get a dropout-free experience and included a short remark about "Rightmark CPU Clock Utility" making Speedstep clock down somewhat less aggressively (but still happening).

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Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

Timur wrote:

Here is a small HOWTO for getting the lowest possible DPC latencies (<100 us) on bootcamped Macbooks Pro (late 2008):
The Nvidia driver shows some quirks apart from the already described behavior. When Aero is turned off: higher idle DPC latencies, more spikes when GUI elements are moved (like moving a window or (un)folding a subtree of the device-manager) and somewhat erratic movement when moving a window. When Aero is turned on it seems to run better, but some actions like maximizing the DPC Latency Checker window can lead to whole blocks of bad latency spikes.

Thanks Timur,
I'm replying to your message from the other thread here for continuity. I followed your recipe. The only thing I was unclear on was the nvidia driver. I found 181 driver and installed it.Should I have installed the 180.84 beta driver? Also, you might have suggested the newer driver was desirable. Finally, is there anything I need to do after installing the new driver? Any settings? I couldn't find anything.

Cheers
Randy

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Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

Hey Randy,

I didn't try the 181 driver yet, but since it's mainly an OpenGL developer driver I don't expect it to bring any performance gains for our Audio applications. The only reason why I mentioned the 180.84 driver is that it was the latest version available when writing the post. I installed it to get a comparison with the Bootcamp drivers supplied by Apple.

For DPC Latencies (and thus Audio performance) the NVidia Vista drivers (for the 9600M GT) are problematic (not so the XP drivers), so the best solution for best Audio performance seems to be using the Microsoft "Standard VGA driver" on Vista until NVIdia provides DPC Latency free drivers (I will try the 181 on my Vista 64 installation next).

Unfortunately the Standard VGA drivers don't support using Aero and that can be a considerable drawback. Believe it or not, but Aero is really an advantage for us Audio application users. There are lots of badly implemented VST plugins (and some DAWs) out there whose GUIs behave erratic or eat performance. Aero catches that all and makes it into a smooth experience (proved by the fatal Vista incompatibility of Ableton Live's GUI drawing methods that until version 7.0.12 ate away CPU cycles like nothing even with only one audio track playing which was easily fixed by using Aero).

Let's hope that both Apple and NVidia get their act together and provide better performing mobile drivers anytime soon. The NVidia 7800GT on my PC desktop shows no relevant DPC spikes whatsoever on Vista neither with or without Aero, so it's obviously possible. fryingpan

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Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

Timur wrote:

Hey Randy,

Unfortunately the Standard VGA drivers don't support using Aero and that can be a considerable drawback. Believe it or not, but Aero is really an advantage for us Audio application users. There are lots of badly implemented VST plugins (and some DAWs) out there whose GUIs behave erratic or eat performance. Aero catches that all and makes it into a smooth experience (proved by the fatal Vista incompatibility of Ableton Live's GUI drawing methods that until version 7.0.12 ate away CPU cycles like nothing even with only one audio track playing which was easily fixed by using Aero).

Let's hope that both Apple and NVidia get their act together and provide better performing mobile drivers anytime soon. The NVidia 7800GT on my PC desktop shows no relevant DPC spikes whatsoever on Vista neither with or without Aero, so it's obviously possible. fryingpan

Interesting. With the wlan disabled, standard vga driver, kbdmgr.exe killed off, my MBP never even reaches 100 microsends. Solid as a rock. With this exercise I also learned how to make my vista laptop solid for audio; again it was wlan disabled and standard vga driver, and latency never got over a millisecond and usually much lower, like in the 100 microsecond range. I'm excited about the MBP as a great windows audio machine.

Would xp fare better with the standard vga driver?

Now, on to tackling the expresscard/onboard fw800 issue to give you some more data points.

Cheers
Randy

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14 Reply by Timur Born (edited by Timur 2009-01-02 00:45:57)

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Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

Randy wrote:

Would xp fare better with the standard vga driver?

Nope, because the Standard VGA driver of XP performs very bad. You can practically see the screen content being build up when using that one. On the other hand the NVidia driver allows for more troubleshooting control on XP and generally produces no troubling DPC spikes.

I also compared Vista 64 and found it to be behaving just like Vista 32 with the exception that Vista 64 allows to use the full 4 GB of the Macbook Pro while Vista 32 only allows 3 GB.

The "BIOS" likely is to blame on the latter, because it seemingly doesn't map the onboard graphic memory (512 MB for the  9600M + 256 MB for the 9400M) over the 4 GB limit.

Unfortunately I cannot use Vista 64 (yet), because 1. there are no drivers for my NI Kore and 2. it doesn't allows to set Ableton Live's priority to "Realtime" which is necessary to overcome a performance bug in Live.

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Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

Timur wrote:
Randy wrote:

Would xp fare better with the standard vga driver?

Nope, because the Standard VGA driver of XP performs very bad. You can practically see the screen content being build up when using that one. On the other hand the NVidia driver allows for more troubleshooting control on XP and generally produces no troubling DPC spikes.

I bought an oem copy of xp pro sp3 and installed it, replacing vista. The nvidia driver is easier to deal with and I didn't have to go to the standard vga driver. However, and I hate to admit this, I miss the vista interface and aero. Just a much more attractive ui. I'm still toying with the idea of going back to vista, but would need to switch to the vga driver for critical audio work, and as you pointed out, there might be plugs that need aero.

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16 Reply by MC

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Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

To get a little bit Vista feeling without any additional CPU load: download the Zune theme for your XP, and then use the famous Yz Shadow (freeware) to get the border shadows for the windows.

Regards
Matthias Carstens
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Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

MC wrote:

To get a little bit Vista feeling without any additional CPU load: download the Zune theme for your XP, and then use the famous Yz Shadow (freeware) to get the border shadows for the windows.

Yes, that does quench the aero thirst a bit. Thanks!

Randy's Website

18 Reply by Timur Born (edited by Timur 2009-01-02 11:52:45)

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Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

Randy wrote:

and as you pointed out, there might be plugs that need aero.

Which is still true when using XP (which offers no Aero aka Desktop Windows Manager/DWM.EXE at all). One has to keep in mind though that in these cases DWM only corrects the GUI drawing issues of the original plugin/DAW GUI. So getting that fixed by the plugin/DAW developers is always to be prefered.

All in all I'm very confinced that Vista is the better OS under the hood (aka it's not just that shiney Aero thingy). Most problems are based on driver and software issues that often derive from bad implementations (which on XP didn't show as often unless something crashed). Vista is more strict in its demands on how software needs to be implemented properly and that's good so. In the end it's build on the very same code base as Server 2008 (even the latest SP2 is the same for both).

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Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

There is some good news: Because of the Windows 7 Beta that will be published in the near future Microsoft has put up a new "Microsoft Update-Catalog" at: http://catalog.update.microsoft.com/v7/site/Home.aspx

This includes many updated drivers for hundreds of hardware interfaces including Broadcom WLAN drivers and Nvidia 9600M GT drivers that are found on the current Macbook (Pro) models.

Especially the Broadcom driver is very interesting:

1. It finally enables full 300 mbit/s 802.11n support, whereas older drivers (including OS X) only connect upto 130 mbit/s with many routers. Whatever the driver does to switch 300 mbit on it even stays on when you reinstall the older drivers!

As a drawback you cannot use channels 12 and 13 anymore (in Germany) as this driver seems to be made for the USA only.

2. It dramatically improves DPC latencies

From this (Bootcamp Broadcom driver version 4.170.77.3/03-21-08):

http://img231.imageshack.us/img231/1552/broadcombootcampiz5.png

To this (Broadcom driver version 5.10.38.26/10-22-08):

http://img261.imageshack.us/img261/8513/broadcom5ds4.png

I would still advice to turn off WLAN when doing critical Audio work, but at least you only have to do it for special circumstances now.

The Nvidia 9600M GT drivers are version 177.48 and thus slightly newer than the Bootcamp ones. Unfortunately they shows about the same DPC Latency behavior as before. So for critical Audio work you still have to fall back to the "Standard VGA Drivers".

PS: Curiously the new driver version of the Broadcom drivers resembles what OS X reports as "Firmware Version: 5.10.38.24". Even more strange Windows 7 Beta comes with a driver version 4.176.75.11/10-23-08 that is one day younger, but less performing than the version 5 drivers.

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Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

Timur wrote:

There is some good news: Because of the Windows 7 Beta that will be published in the near future Microsoft has put up a new "Microsoft Update-Catalog" at: http://catalog.update.microsoft.com/v7/site/Home.aspx

This includes many updated drivers for hundreds of hardware interfaces including Broadcom WLAN drivers and Nvidia 9600M GT drivers that are found on the current Macbook (Pro) models.
<SNIP>

Wow Timur. You're awesome. Very interesting news. I was planning on installing vista over xp today since I really miss vista (I use it on my HP laptop) and since nothing works for me on XP anyway, there's nothing to lose. I ordered the Lindy repeater (4.5M??? a bit longer than I need) which has shipped and will arrive friday, so something will work.

So it looks like if I get windows 7 beta I can use those drivers. cool. Also, I noticed vista sp2 beta. Have you played around with it? Maybe it has the newer drivers too?

Thanks again Timur for sharing all of your hard work with us.

Randy's Website

21 Reply by Timur Born (edited by Timur 2009-01-06 22:47:40)

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Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

Randy wrote:

Wow Timur. You're awesome. Very interesting news.

Thanks for the flowers! :-D

I ordered the Lindy repeater (4.5M??? a bit longer than I need) which has shipped and will arrive friday, so something will work.

If the Lindy is too inconvinient (long) for you, you can just try a simple Firewire Hub and put a short cable in between. A combination of powered Firewire and USB hub could be quite convinient, too.

So it looks like if I get windows 7 beta I can use those drivers. cool.

That's what the site is made for! wink

Also, I noticed vista sp2 beta. Have you played around with it? Maybe it has the newer drivers too?

I notice nothing special about SP2. In general it's just a combined package for all the little updates and patches that were released after SP1. I doubt that there are any special drivers in there. The worst culprit remain the ACPI Battery driver (spike every 15s on Vista, also happening in Windows 7 btw) and the NVidia graphic-drivers (same behavior in Windows 7).

Thanks again Timur for sharing all of your hard work with us.

I have to do the analysing work for my own projects anyway. Writing it all down in a is the extra work part. ed:

22 Reply by Timur Born (edited by Timur 2009-01-12 19:02:09)

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Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

Some Updates:

1. NVidia now officially offers graphic-drivers for their mobile line of GPU including the 9400M/9600M that are found in the Macbook (Pro). So you can just download the latest drivers directly from NVidia now without any need to mess with INF files or any other hack.

2. I have found the source for the DPC Latency spikes that are happening with NVidia graphic-drivers installed. Actually there are two reasons for this happening.

a) The Nvidia driver dynamically changes the GPU clock-rate (including GPU memory) up and down depending on current graphic-load. Everytime the clock-rate changes (especially when it changes down) a huge DPC Latency spike happens. This has been reported with Geforce-8 based GPU on other forums and unfortunately the 9600M is more of a Geforce-8 than Geforce-9.

b) When graphic-load is low (like with most 2D based DAWs) the GPU memory is clocked down to only 100 MHz (from a max of over 700 MHz), this leads to regular and ongoing DPC Latency spikes when many dymanic elements are displayed by a DAW.

I have already managed to temporarily get rid of NVidia based DPC Latency spikes and I'm working on finding a solution that allows to permanently get rid of those during DAW work. I will report back on that.

Until then the best performing option that leads to the lowest average DPCs is still to switch the graphic-driver to "VGA Standard Driver" (minimum power draw will be upto 5W higher though).

3. Nvidia also offers an application called Ntune at version 6. NTune allows you to overclock/underclock the Frontsidebus (and thus the CPU and RAM), modify RAM timings and overclock/underclock the GPU. Only experienced people who know what they are doing should mess with it, but it's nice to have for those of us who like messing around anyway. wink

23 Reply by Randy (edited by Randy 2009-01-12 20:20:12)

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Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

As stated in previous posts, with my Latebook no express cards work running bootcamped vista sp1, and while my Konnekt 24d works under osx, when running vista(same with xp) whenever I plug it in the machine freezes. If I try to reboot with it plugged in it never gets past the black screen but the fan revs up slowly and ever increasing. I have been tempted to see if I leave it long enough it will explode. Anyway, I ordered and received the Lindy repeater. I tried it but it had no effect. I have logged a support case with TC.

So now I have a Lindy repeater I don't need. It's a great cable but back it goes.

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24 Reply by fl

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Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

Timur wrote:

Some Updates:

1. NVidia now officially offers graphic-drivers for their mobile line of GPU including the 9400M/9600M that are found in the Macbook (Pro). So you can just download the latest drivers directly from NVidia now without any need to mess with INF files or any other hack.

Thanks for publishing all this information, Timur. Although my late 2007 MacBook Pro (running XP SP3 under Bootcamp) uses the NVIDIA GeForce 8600M GT graphics processor, I was able to find the newest drivers for that, and it has improved things a lot.

Using Merging Technology's Pyramix software, I used to see heightened DPC Latencies when I put Pyramix into Play, even higher when in Record, and highest when I had the level meters visible in the track headers.  With the new drivers, I now see none of this behaviour, and even recording multiple tracks, I'm only rarely exceeding 300 micro-seconds of DPC Latency.  In the Device Manager, getting the Properties of the NVIDIA driver, I see I'm now running version 6.14.11.7928.

Thanks again for your work and research.

Frank Lockwood
https://LockwoodARS.com
Fireface 800, Firmware 2.77
Drivers: Win10, 3.125; Mac, 3.36

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Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

Randy wrote:

but the fan revs up slowly and ever increasing. I have been tempted to see if I leave it long enough it will explode.

hehe...do it...do it!!!....damn computers...they need to be exploded every now and then to show them who is really the boss and make us all feel better.

Andrew.

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Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

Preamp wrote:
Randy wrote:

but the fan revs up slowly and ever increasing. I have been tempted to see if I leave it long enough it will explode.

hehe...do it...do it!!!....damn computers...they need to be exploded every now and then to show them who is really the boss and make us all feel better.

Andrew.

Ah, I wish it were so easy. Those diabolical robots have a mechanism where they protect themselves by shutting off when things get too hot. cowards!

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27 Reply by Dandruff (edited by Dandruff 2009-01-14 07:34:56)

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Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

Timur wrote:

a) The Nvidia driver dynamically changes the GPU clock-rate (including GPU memory) up and down depending on current graphic-load. Everytime the clock-rate changes (especially when it changes down) a huge DPC Latency spike happens. This has been reported with Geforce-8 based GPU on other forums and unfortunately the 9600M is more of a Geforce-8 than Geforce-9.

Maybe you can solve it by adjusting the (throttling)settings directly in the BIOS with NiBiTor and nvFlash
Just don't know if it works with mobile/notebook cards ...

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Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

Thanks for the input Dandruff. I thought about that, but messing with these on a 2300 Euro expensive Macbook Pro seems quite a dangerous mind to taste. wink

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Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

I have one bad news and two lightly good news:

Bad news: I was not able to keep the Nvidia 9600M GT from switching down to 2D mode sooner or later. Even when it is possible to keep it from switching clock-rates in performance-3D and low-power-3D by setting those to the same clock-rates once it goes down to 2D the performance is rather bad aka DPC latencies are regular high enough to make it unusable for low latency audio work. It seems that the lower the memory clock the higher the DPC latencies.

1. good news: "For a limited time, provide your feedback on Rel 179 notebook drivers."

http://surveys.nvidia.com/index.jsp?pi= … dd3baa920a

So for the first time they offer us end-users to tell them what we think about the performance of their drivers. I will use that opportunity to tell them about bad DPC behavior! wink

2. good news: NVidia not only officially offers drivers for the graphic-card but also for the system chipset. You can find it under "NForce -> NForce7 -> 730i/Geforce 9400m/9300m mGPU". The current version is already a bit more up-to-date than the ones on the Bootcamp disc.

3. good news: I forgot what it was, but I'm sure there was a third good news. smile

  • Registered: 2008-04-02
  • Posts: 13

Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

Hi Timur,

I've been following the MacBook Pro/RME saga from afar for quite a while. I have a FF400 sitting here and I've been trying to decide whether to go through with buying a MBP. What an AMAZINGLY sweet combination that SHOULD be.

Anyway, I just wanted to say that I really appreciate your enthusiasm for passing on your knowledge.

Cheers,
Andrew.

p.s. your avatar always makes me think of Dave Grohl...

  • Knut
  • Knut
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  • Registered: 2007-04-06
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Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

I've been trying to decide whether to go through with buying a MBP. What an AMAZINGLY sweet combination that SHOULD be.

We recommend to wait for the upcoming new revision 7 of the LSI /Agere FW chip in the MBP. This will probably fix all current problems. We don?t know when this will happen - maybe already in the upcoming MBP 17 -  but will post it here immediately when we get some solid information.

best regards
Knut

  • Registered: 2008-01-01
  • Posts: 3,025

Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

Update: I didn't give up and finally found a way to keep the NVidia graphic from producing DPC Latencies on Vista/W7 while NVidia drivers are used (instead of just using VGA Standard drivers).

Furthermore I found that the only reason why Windows XP is not affected by NVidia induced DPC Latencies is because the graphic card's clock-rates are never changed but keep running at the highest settings (Performance 3D), not even when installing the latest drivers. This is a bug! The obvious drawback is that power drain and likely GPU temperatures are somewhat higher compared to Vista/W7.

Actually I found two ways to stop NVidia DPC Latencies from happening on Vista/W7. Since the reason for the DPC Latencies are:

1. dynamically switching clock-rates
2. running at low performance 2D mode most of the time

We need to get rid of both! One way is to switch to the Microsoft VGA Standard driver which makes the 9600M run at fixed "medium" clock-rates for both GPU and memory. But since this not only means to abandon Aero, but also Nvidia video-playback acceleration and other driver goodies it's only the second best option.

The best option I found is to use an application called Rivatuner that offers a somewhat hidden option called "Force Performance Mode". This allows to set the NVidia driver to one of it's three modes: "Standard 2D" (we don't want that!), "Low Power 3D" (comparable to Standard VGA driver clock-rates), "Performance 3D" (that's what XP gets stuck at).

I recommend enforcing the "Low Power 3D" mode for audio work. You need to restart the computer in order to switch the "Force Performance Mode" on and off in case you need to get the old behavior back or need the full "Performance 3D" mode for gaming, but that's not too much of an inconvenience. It also works on XP by the way.

The second method I found is a bit too geeky and needs too much work to setup so I wont explain that in detail. The general idea of that second idea is that once a DAW GUI is loaded any switching of GPU clock-rates forces the GPU back to "Performance 3D" mode (even when the rate doesn't actually change). So a regular occurring switch every few seconds would keep the rate constant. I prefer method 1 even when that means to reboot for changing it.

PS: I will write some details on how to find the "Force Performance Mode" option inside of Rivatuner later and put the updated details into the original first post then.

  • Registered: 2008-04-02
  • Posts: 13

Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

We recommend to wait for the upcoming new revision 7 of the LSI /Agere FW chip in the MBP. This will probably fix all current problems. We don?t know when this will happen - maybe already in the upcoming MBP 17 -  but will post it here immediately when we get some solid information.

best regards
Knut

....been waiting 18 months to get a laptop. I guess I'll keep waiting...any news on the new chip will be MUCH appreciated Knut.

Thankyou,
Andrew.

34 Reply by Timur Born (edited by Timur 2009-01-16 14:18:51)

  • Registered: 2008-01-01
  • Posts: 3,025

Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

As promised I updated the original post. Here is a short guide how to activate the "Enforce Performance Mode" option in RIVATUNER.

Open RIVATUNER and switch to the "Power User" tab.
Expand the "RivaTuner\NVIDIA\Overclocking" Tree.
Set "EnablePerfLevelForcing" to 1.
Switch to the "Main" tab.
Under "Driver settings" click on the small arrow left to "Customize..." and chose the first icon "System settings".
Set "Force constant performance level" to either "low power 3d" (suffient for 2d audio work) or "performance 3d" (used for 3d gaming).
Click OK and let the computer restart.

  • Registered: 2008-01-01
  • Posts: 3,025

Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

I spent some time to get more convinient control over KBDMGR and the corresponding settings application (the one you configure the trackpad and F-keys behavior besides other stuff).

Right ALT-. will switch KBDMGR on and off now. Additionally the F-keys are automatically switched to their special Macbook functions (like controlling brightness) when KBDMGR is on and to normal F-keys function when KBDMGR is off.

Furthermore when Windows boots up and when enabling it via ALT-. then KBDMGR is set to "Idle" priority and CPU1 affinity. That helps for normal desktop audio output, but for professional audio work it still needs to be turned off.

Right ALT-, will open up the settings dialog now. It also works with KBDMGR being disabled including setting brightness via the slider.

PS: While I was at it I also remapped the key left to the backspace to act as DEL (it's the never used key `? on german keyboards) and the right CMD key to act as CTRL (so I can use it like on the OS X).

36 Reply by Randy (edited by Randy 2009-01-21 09:19:56)

  • Randy
  • Randy
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  • Registered: 2008-12-21
  • Posts: 77

Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

Timur wrote:

I spent some time to get more convinient control over KBDMGR and the corresponding settings application (the one you configure the trackpad and F-keys behavior besides other stuff).

<SNIP>

How are you doing this, and how can I do it? It sounds great.

Randy's Website

37 Reply by Timur Born (edited by Timur 2009-01-23 02:35:39)

  • Registered: 2008-01-01
  • Posts: 3,025

Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

Here's a small toolkit I put together. Installation instructions are included in the README.TXT for your convinience. wink

[url=http://www.screencast.com/t/7HhqtFZLpf]Boot CampED - Download Page[/url

  • Registered: 2008-01-01
  • Posts: 3,025

Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

I put up some better download links!

39 Reply by fl

  • fl
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  • From: Toronto, Ontario, Canada
  • Registered: 2007-11-12
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Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

Hmmm, it's been so long since I killed the KBDMGR.EXE I've forgotten how to re-enable it to try out Timur's fix.  Can some Windows savvy person help me out?

Frank Lockwood
https://LockwoodARS.com
Fireface 800, Firmware 2.77
Drivers: Win10, 3.125; Mac, 3.36

fl's Website

  • Registered: 2008-01-01
  • Posts: 3,025

Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

Just reinstall Boot Camp from the CD's "drivers/apple" directory (or look wether you disabled KBDMGR.EXE vis Msconfig). I tried whether one can start KBDMGR just after bootup, but for some strange reason it wont work then (eventhough it really only does autostart via the RUN entry of the Registry).

  • From: Houston, TX
  • Registered: 2007-05-11
  • Posts: 1,191

Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

I use Rivatuner simply for increasing my GPU's fan speed - I'll have to try the 3D Performance tweak you mentioned to see if that helps my silly Vista DPC spikes (I'd assume this is true for ANY PC with nVidia Drivers, not just a bootcamped MAC, correct?).

PS - When do you find time to sleep?  :-P

cool

MADIface-XT+ARC / 3x HDSP MADI / ADI648
2x SSL Alphalink MADI AX
2x Multiface / 2x Digiface /2x ADI8
  • Registered: 2008-01-01
  • Posts: 3,025

Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

I fixed a bug with my "Boot CampED" tool package that prevented it from switching priority to Idle and affinity to CPU1.

Here is a new a better link that wont get obsolete once I upload a new version:

Boot CampED - Download Page

  • Registered: 2008-01-01
  • Posts: 3,025

Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

Randyman... wrote:

I use Rivatuner simply for increasing my GPU's fan speed - I'll have to try the 3D Performance tweak you mentioned to see if that helps my silly Vista DPC spikes (I'd assume this is true for ANY PC with nVidia Drivers, not just a bootcamped MAC, correct?).

Before you try to enforce a fixed Performance Mode have a look at the clock-rates readings first. Use Rivatuner Monitoring tool for that and watch DPCs while clock-rates change (use NVidias 3D preview that is found in its settings).

I'm using a 7800 GT in my desktop PC and don't need these tricks there, because it doesn't perform just as good in 2D as in 3D and once it settles there it usually remains there. But the desktop card uses alot higher memory frequencies when in 2D (actually it never turns those down, which is why I use Rivatuner to do that for 2D).

PS - When do you find time to sleep?  :-P

Now!journey Generally I get a good share of at least 7 hours, sometimes more per night. But I'm working alot on the computer and all these audio-computer related things, that's why I'm so active in forums at the moment. I like sharing and discussing what I find. wink

  • From: Houston, TX
  • Registered: 2007-05-11
  • Posts: 1,191

Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

You are indeed everywhere!  I'll try your Rivatuner suggestions tonight on my one nVidia equipped rig.  Thanks!

cool

MADIface-XT+ARC / 3x HDSP MADI / ADI648
2x SSL Alphalink MADI AX
2x Multiface / 2x Digiface /2x ADI8

45 Reply by Timur Born (edited by Timur 2009-01-23 13:06:39)

  • Registered: 2008-01-01
  • Posts: 3,025

Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

Also make sure to set your system on load while using the DPC Latency Checker, especially on Vista 32-bit! If DPCs on load are low then you don't have too worry that much, because usually your CPU will also be on high load while using a DAW. But it's not a perfect situation, that's why I'm using Coolbook on OS X (and set power-managment to ALWAYS ON on XP with my AMD X2 CPU which unfortunately wont work for Intel Speedstep).

Use Prime95 for that, because it will produce all of its load at the very lowest possible CPU priority 1 and thus not interfere with any other software (CPU heat will increase considerably though).

46 Reply by fl

  • fl
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  • From: Toronto, Ontario, Canada
  • Registered: 2007-11-12
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Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

Timur wrote:

Right ALT-. will switch KBDMGR on and off now.

Unless I'm missing something, there is no Right Alt key on a MacBook Pro keyboard - to what are you referring?

Frank Lockwood
https://LockwoodARS.com
Fireface 800, Firmware 2.77
Drivers: Win10, 3.125; Mac, 3.36

fl's Website

47 Reply by Timur Born (edited by Timur 2009-02-26 17:10:13)

  • Registered: 2008-01-01
  • Posts: 3,025

Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

It's called "option" on english keyboards, but "alt" on german ones. wink

In Windows it corresponds to pressing CTRL+ALT together (and thus is called "Alt GR" on german PC keyboards). In Windows you can set keyboard shortcuts within the properies of any Icon shortcut that react to a key-combination of "CTRL+ALT+<key>". Using the right option/Alt key is just an easier way of using these.

48 Reply by fl (edited by fl 2009-02-26 20:40:41)

  • fl
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Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

Timur wrote:

It's called "option" on english keyboards, but "alt" on german ones. wink

In Windows it corresponds to pressing CTRL+ALT together (and thus is called "Alt GR" on german PC keyboards). In Windows you can set keyboard shortcuts within the properies of any Icon shortcut that react to a key-combination of "CTRL+ALT+<key>". Using the right option/Alt key is just an easier way of using these.

Perhaps there is a different keyboard provided with MacBook Pros released for the European markets, but on my machine, there is only one key to the right of the space bar, and that is the Command or Apple key, then an "Enter" key and then the four arrow keys, so your program, as is, will not work on my machine.  To further complicate matters, I've already used the program, "Key Tweak" to re-map the Command and Control keys on the left side of the space bar, because I'm so used to the Mac way of doing things - the way Windows utilizes the Control key for everything is almost as annoying as popping the Start Menu up every time I hit the Command key...

Frank Lockwood
https://LockwoodARS.com
Fireface 800, Firmware 2.77
Drivers: Win10, 3.125; Mac, 3.36

fl's Website

49 Reply by Timur Born (edited by Timur 2009-02-26 21:01:22)

  • Registered: 2008-01-01
  • Posts: 3,025

Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

As far as I know Apple got rid of the second ENTER key all together and replaced it with the second option key on all new keyboards. Whatever...

1. The batchfiles will work anyway, because the keyboard shortcut is just for convinience. You can simply use the icon shortcut to start the batchfile.

2. Like I wrote before you can simply use CTRL+ALT (aka CTRL+OPTION) which is the very same as using the right alt/option key. It's just the default way of how Windows provides keyboard shortcuts.

3. You don't need to use the batchfile, it's just for convinience. You can simply kill KBDMGR manually via Task-Manager and change its CPU affinity there, too.

PS: I was told by one user that on his XP installation the START command used by the batchfile doesn't offer the "/AFFINITY" switch. If you others are experiencing the same problem then simply remove that all references to that switch from the batchfiles.

50 Reply by fl

  • fl
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  • From: Toronto, Ontario, Canada
  • Registered: 2007-11-12
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Re: HOWTO: Low DPC latencies (<100 us) on bootcamped Macbooks (Pro)

Aren't there problems associated with re-starting KBDMGR after it's been killed in the Task Manager?  I thought I read somewhere that it will lock up the computer, or BSOD it...

Frank Lockwood
https://LockwoodARS.com
Fireface 800, Firmware 2.77
Drivers: Win10, 3.125; Mac, 3.36

fl's Website