Intel Core i7

jksuperstar

So, I keep seeing Audio latency tests, in both Windows XP/Vista/7 and Linux, that show 17us typical, with 66us max. Carefully selecting the core affinity, and you can improve this more.

So, worst case, that's down to 3 samples at 44.1kHz!! This is a really great thing for audio, if the ASIO drivers and the host buffers support it.

I have an 'older' Core2Duo laptop, and in Ableton, I can already use 32 sample deep buffers between VSTs, and get 2-5ms latency in my audio card (Emu 1616m).

Switching to a core i7 could really change things: This new low latency, and the fact that a quad-core i7 can do upwards of 75GFLOPS, is a shit-ton of power, and honestly can replace a lot of extra gear I have laying around. Possibly even my G2.

Thoughts? Any other hints at getting real latency down on a PC into the double or single digit range of samples? I'm not looking for imperceptible latency, but the fact that I can work with audio buffers of a couple of samples, which opens the world up for real-time audio-rate synthesis on a PC.

jksuperstar · Posted: Fri Mar 12, 2010 11:15 am Post subject:

links:

http://www.osadl.org/Single-View.111+M594f3c2c67e.0.html

These results are nuts, look at the DPC latency reported on recent chips!! (Scroll down to post #66 and beyond)..

http://www.xtremesystems.org/forums/showthread.php?p=4274278

DrJustice · Posted: Sat Mar 13, 2010 7:59 am Post subject:

Very interesting, jk!

The laptop I'm running here periodically (every minute or so) throws a slow building up of DPC latency to > 4mS. Ref. the attached picture. Strange... there's some real garbage driver running on it. The system is a 3 year old Dell Latitude D820 with T2500 CPU @ 2GHz. Nothing is tweaked in any way - this is my work/coding/browsing machine so it's not critical.

I'm planning on an i7 laptop to use as a DAW. Hopefully it will fare a lot better, as in exhibiting a more consistent lowish latency. Then the rest is up to how clever the drivers and audio/MIDI hardware are...

DJ
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jksuperstar · Posted: Mon Mar 15, 2010 7:33 am Post subject:

Ugh..the desktops easily see 2x performance, more like 3x over the mobile versions. I need to think how I can turn my rig into an all-in-one unit so it's easy to move around, and still have a desktop processor involved.

soundwave106 · Posted: Mon Mar 15, 2010 5:30 pm Post subject:

jksuperstar · Posted: Mon Mar 15, 2010 9:01 pm Post subject:

DrJustice · Posted: Tue Mar 16, 2010 4:41 am Post subject:

Ha ha - well the work as such is critical enough, but running text editors and compilers doesn't really need interrupt responses of a few µS. If bits of code were skipped like lost audio buffers I'd start to worry Laughing

After your initial posting I took an interest in this, and it seems that on some (Dell) systems there is not a lot you can do to straighten it out - some have the DPC offenders locked into the BIOS, dependent on fixes from the manufacturer. I'll definitely do some careful research before deciding on a laptop for DAW use.

DJ
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jksuperstar · Posted: Tue Mar 16, 2010 7:46 am Post subject:

I'm driving myself mad over hear, trying to figure out the best combiniation of processor and GPU. Since I started looking into OpenGL and especially OpenCL, I'd really like to see what a processor (GPU) that isn't servicing OS and peripherals is capable of in computing realtime audio Smile

YAP (Yet Another Project)....

Antimon · Posted: Tue Mar 16, 2010 8:35 am Post subject:

Not knowing much about it, I share your enthusiasm for non-graphical use of the processing power in graphics cards. Someone should patch ChucK to use it!

/Stefan

DrJustice · Posted: Mon Mar 22, 2010 1:29 pm Post subject:

Just an update re. that DPC latency curve above: it was th DVD R/W driver... with it disabled, the curve is nice and flat, never above 800µS and mostly around 100µS. So, a damn idling DV-ROM driver made by "Toshiba Samsung Storage Technology Corporation" doing that!?!? How is it even possible...

DJ
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