CPU performance meters disappear with ultra low latency?

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Shambler
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2016/09/22 12:49:56 (permalink)

CPU performance meters disappear with ultra low latency?

Hi all,
 
I've just added a Scarlett 18i20 and noticed that if I run it at a buffer size of 16 at 48KHz the CPU performance meters in SONAR disappear.
 
Increasing the buffer to 32 or greater and they come back.
 
Anyone else see this?

SONAR Platypus on Win10 64bit.
Studio One Pro / Cubase Pro 9.5...just in case.
8GB i7-2600 3.4GHz Gigabyte  Z68XP-UD3P
Geforce GTX970
Focusrite Scarlett 18i20 2nd Gen
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    JonD
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    Re: CPU performance meters disappear with ultra low latency? 2016/09/23 10:10:57 (permalink)
    64 buffer size is considered ultra-low by most here and not even achievable by many.
     
    16 is likely stressing your system way too hard.  You should find the "sweet spot" and not push it that low just because you can.
     
    By all means, report it to Focusrite, but if there's no problem at 32 buffer and above, I honestly wouldn't sweat it.
    post edited by JonD - 2016/09/23 10:32:21

    SonarPlat/CWbBL, Win 10 Pro, i7 2600K, Asus P8Z68 Deluxe, 16GB DDR3, Radeon HD5450, TC Electronic Impact Twin, Kawai MP11 Piano, Event ALP Monitors, Beyerdynamic DT770 Pro, Too Many Plugins, My lucky hat.
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    brundlefly
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    Re: CPU performance meters disappear with ultra low latency? 2016/09/23 12:18:43 (permalink)
    Yes, I lose Perf Meter bars at 16 samples. Light projects play fine at that buffer size, but anything that spikes DPC latency is likely to cause a dropout and I can hear the CPU working overtime so I almost never run it that low.

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    scook
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    Re: CPU performance meters disappear with ultra low latency? 2016/09/23 12:33:25 (permalink)
    My guess it is the buffer processing is so fast there is nothing to display. From http://www.cakewalk.com/D...elp=ControlBar.11.html

    CPU meters. Displays the time it takes to process a buffer full of audio data as a percentage of the maximum time available to process that data and maintain uninterrupted playback.

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    Shambler
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    Re: CPU performance meters disappear with ultra low latency? 2016/09/23 14:16:57 (permalink)
    I'm Superconducting!
     
    This is without any VST instruments running, just streaming in audio from SPDIF and a few effects.
     

    SONAR Platypus on Win10 64bit.
    Studio One Pro / Cubase Pro 9.5...just in case.
    8GB i7-2600 3.4GHz Gigabyte  Z68XP-UD3P
    Geforce GTX970
    Focusrite Scarlett 18i20 2nd Gen
    Prophet 12/Rev 2/Virus Snow
    Zebra2/DIVA/NI Komplete 10
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    brundlefly
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    Re: CPU performance meters disappear with ultra low latency? 2016/09/23 15:00:38 (permalink)
    scook
    My guess it is the buffer processing is so fast there is nothing to display. From http://www.cakewalk.com/D...elp=ControlBar.11.html

    CPU meters. Displays the time it takes to process a buffer full of audio data as a percentage of the maximum time available to process that data and maintain uninterrupted playback.





    My guess is that with a buffer being processed every 333us there isn't enough time for the process that calculates the height of the bars to complete, and the variables that store the height of each bar are just staying at their initialized value of 0. That or it was just coded to skip the Perf Meter routine when the buffer is set below 32 samples because it's not feasible to deliver meaningful values.

    SONAR Platinum x64, 2x MOTU 2408/PCIe-424  (24-bit, 48kHz)
    Win10, I7-6700K @ 4.0GHz, 24GB DDR4, 2TB HDD, 32GB SSD Cache, GeForce GTX 750Ti, 2x 24" 16:10 IPS Monitors
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