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  • Diagnosing Real Time Performance

    I have two machines currently, a beefy Dual Xeon Supermicro PC and a Hackintosh 6-core 3930k DAW running Digital Performer 9.02. Audio interface is MOTU 424 card with a 2408mk3.

     

    I could use some help diagnosing what looks to be a real time performance issue. I'm trying to play back a sequence at a 256 buffer. When it gets to a section of the music that's very active, the "Processing" bar in DP goes from barely there to being completely pegged solid red with dropouts and dragging tempo. 

     

    Here's what I've tried:

    • I think I've eliminated the PC sample machine as being the culprit. The CPU does not get above 33% during playback with no dropouts or visible spikes of any kind. Also, running DPC latency checker while playing back the sequence hardly changes and hovers around 60us, stays in the green the whole time.
    •  Back on the DAW side, HW Monitor seems to suggest that the CPU is throttling down during the tough section. This to me suggests the bottleneck is not the CPU, it seems like something is locking the CPU so it can't process.
    • In DP, I've eliminated all plugins. The only plugin that is active in the session is VE PRO. 
    • If I switch to a buffer of 512, all is well and the processing never spikes. I could stay here, but I'd really like to have a bit better latency. If I can diagnose the spike, my current CPU should be able to handle this no problem.

    Is there anything like LatencyMon or DPC Latency Check for OSX? What steps am I missing for diagnosing the spike?

    Edit: I'm only using one instance of Ve Pro as that seems to get the best performance, with a total of 34 channels of audio being sent back to the DAW. Also, the machines are connected via LAN directly, no switch in between.  

    Thanks for your time.

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  • I still cannot play back a demanding sequence at a 256 buffer with no other plugins loaded other than one instance of VE Pro. Playback at 512 has virtually no system stress whatsoever, so I can still work with the delay. However, low latency is my holy grail. So on to diagnosing-

    Processing spikes occur in Windows 7 and OSX, so it doesn't seem to have anything to do with OSX specific drivers. Also, ran DPC Latency and LatencyMon during playback while in Windows7, all drivers seem to come back below 1ms. The only driver that's a slight problem is NVidia, but it's still not a big offender, and isn't locking up the CPU during playback. 

    So, possibilities for the bottleneck are:

    Disk Speed: Using all SSDs, but my motherboard has two SATA controllers. Intel and Marvel. I'll have to dig and see where the system drive is hooked up. If it's currently hooked up to the Marvel controller, I'll swap the cable for an Intel SATA Port and see what that does. 

    Sample PC: It's possible the machine is somehow choking even though spikes happen only on the DAW side. While I monitor processing on the Sample PC - the performance is even across all cores at about 33% with no visible spikes. It's practically symetrical across 32 threads. Gotta love VE PRos hyperthreading! In order to fully test this, I'd need a second sample machine so that will have to wait. 

     

    Network connection: Even connecting directly with no switch, the sequence chokes with only 17 stereo channels. I've heard of people running much more than that over LAN. On my Sample PC, I have dual Gigabit ports directly through the Supermicro board, so that's probably not the bottleneck. On my DAW, I have an Intel controlled connection directly to the motherboard as well, but you never know.

    The next step is I've bought an Intel x540_t2 dual 10Gb ethernet card for my DAW machine. I'll split the Server instance into two, establish two different connections with different subnets for each Ethernetport. This will split the network load between two ports. If that doesn't fix it, the network is probably not the bottleneck. 

    VE Pro's Server Plug In: I'm trying to find some RME gear to see if connecting via ADAT helps. The plug in is so well written this is my least likely guess, but you never know. Might be some unique conflict with my system.

    I'll report back pn any findings, but util then any other bottlenecks that I'm not thinking of? 


  • Have you tried just running on the PC as local host, and just not even using the Hackintosh? I am basically to the point where a slave is not even necessary. Kind of depends on what you are doing, but I ended up experiencing the slave actually degrading my overall system performance and didnt really bring me any added benefit over just running everything on a beefy single box as local host.


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    @Synetos said:

    Have you tried just running on the PC as local host, and just not even using the Hackintosh? I am basically to the point where a slave is not even necessary. Kind of depends on what you are doing, but I ended up experiencing the slave actually degrading my overall system performance and didnt really bring me any added benefit over just running everything on a beefy single box as local host.

    Although everybody has their own unique workflows that fit their needs the problem with running slaves is with one machine about a thousand things could go wrong.  When you add a slave now a million things.  Two slaves, two million and so on.

    I would estimate that half the posts on this forum are people complaining of problems with their slaves: "I can't get these machines to connect, These ip addresses don't work, The slaves won't recognize the licenses on my fifteen dongles, I can't generate the 1.5 gigawatts to get the Flux Capacitor to overturn, etc."

    Okay, maybe I'm exagerating a little but you get the idea.

    Again, you do what you have to in order to make your musical dreams a reality no matter how many Rube Goldberg solutions you use but I've always gone through life with the KISS model in mind😃

    I apologize to you RootNDoo because this is more of a rant than a fix to your problem and I hope somebody can help you but for the benefit of others who are considering a slave system...