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Old 10-14-2019, 08:25 AM   #1
azslow3
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Default Computer performance problem, looking for ideas... [SOLVED]

I try to help a friend to find the bottleneck in his system...

Windows 10, i7 3.4GHz, sufficient RAM, SSD, RME. He can not record using VSTi with ASIO buffer under 256.

We have found one indication what the problem is, in the REAPER performance monitor. But nowhere else...

One track with Native Kontrol and Alicia Keys loaded.
REAPER Performance monitor, with RT information enabled.
Once the track is armed and something is played, we have observed under 20% RT CPU use, but more then 1.8ms longest RT processing. That obviously completely prevent working with 64 samples ASIO buffer size, also once more then one track is armed, even 256 samples buffer is no longer sufficient. RT CPU use is way under 50%. But longest RT processing is over 10ms. Sure, enabling multi-threading for RT helps with parallel recorded tracks. But I guess it should be possible to work with buffer 64 on such system.

In case someone has Alicia Keys, Native Kontrol and 3.4GHz i7 processor. Which numbers are reported by REAPER for you during recording or playback in armed state?

We have already checked that latency monitor has everything under 340uSec, CPU is around 3.4GHz all the time, Windows in performance power plan, CPU temperature is 30 degree, bridge 40, no single core shows more then 30% use, RAM is not filled.

It will be nice to know which numbers we should expect. As a hint what should we expect in case the system works as it should.

Last edited by azslow3; 10-18-2019 at 11:29 AM.
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Old 10-14-2019, 10:53 AM   #2
Stella645
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And how does the RME connect to the computer??
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Old 10-14-2019, 12:16 PM   #3
azslow3
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Quote:
Originally Posted by Stella645 View Post
And how does the RME connect to the computer??
USB. But RT performance monitoring in REAPER is interface independent, and we see clear problem there.

It looks like the computer has "insufficient power" for the synth. The puzzle is what is "insufficient". CPU consumption (in RT, tracks as well as in external monitoring) is rather low. So the plug-in is throttled by something else. Could be the disk, but after initial loading all samples should be in cache (RAM is not filled).
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Old 10-14-2019, 12:46 PM   #4
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Get a baseline on your system before inserting any plugins.

Find the lowest block size you can run stable with.
48k sample rate is normally the sweet spot for lowest latency with lowest CPU hit. (HD sample rates cross the line and take more CPU for the same latency vs 48k. 44.1k however is no lower CPU use but higher latency outright.) You can vet that with loopback tests.

Then when you know what your system (interface + computer) can achieve for a baseline, start introducing the big plugins you want to use.

That you are seeing dropouts but not a lot of CPU hit suggests you are dealing with plugins that have a minimum operating latency that is higher than your minimum required block size to hit your required latency. If and when that happens, you need an interface with a baseline low enough latency to let you run with a larger block size and still hit your round trip latency requirement. RME should be one of the good ones in that area FWIW (even their USB connecting models). Or... you have to compromise and only use plugins with lower inherent latency.

That's the approach to take.
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Old 10-14-2019, 02:45 PM   #5
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Make sure that there is no virus software or any type of "real-time" protection running in the background, or for that matter, anything at all that is not related to recording.

Also, does the same thing happen when you close the Kontakt window? I mean set the settings how you want, then close the Kontackt window and record.
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Old 10-14-2019, 11:52 PM   #6
azslow3
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Thank you for replies. We already know with which settings the system runs without glitches in sound. The problem that these settings are strange for the system specification and observed system load.

GUI is not changing strange parameter we observe (RT longest-block).

Please let us know the number you see there, with just one instance of Alicia loaded into Komplett Kontrol. So we know what should be there.

My old desktop shows relatively high value with Kontakt. But I do not have payed NI instruments, and E7500 is not modern i7.
My i7 based notebook shows significantly lower numbers with instruments I use, but again, I do not have Alicia and notebook i7 is not desktop i7.
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Old 10-15-2019, 08:19 AM   #7
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After complete REAPER re-installation, we observe way better value:
RT longest-block around 0.8ms, no more then 1ms. So 64 samples buffer works now (1.45ms limit).

Still, is that new value good for one Alicia instance in Komplete Kontrol?

We have also done benchmarks, everything looks in upper part for that hardware (except Memory which we have not managed to make working in XMP, so "stock" speed for gamer memory...).
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Old 10-15-2019, 07:54 PM   #8
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Which i7 is it? (2600, 6700, etc).

My Performance Meter reads .36ms / 1.33ms. This is a i9-7940x @ 3.10GHz, with Alicia Keys inside KK, slamming chords repeatedly. Buffer is at 64ms. Interface is RME Fireface UCX connected via USB.

There is disagreement as to whether the "Enable MMCSS" box should be checked on the "About" tab of the RME USB settings window (the one available from the tray on the taskbar), and RME's suggestion is to try it both ways, as it affects the thread priority (reset the ASIO stream each time before checking). For me it works best NOT checked, but try both.

Also note this comment from RME here:

Quote:
Reaper may or may not override driver based MMCSS, depending on the Preferences set in Reaper.

Preferences -> Audio -> Device -> Audio thread priority:

ASIO Default / MMCSS Pro Audio / Time Critical: Keeps the driver based MMCSS priority intact (26 with RME drivers, if enabled, else non MMCSS priority 15)

Time Critical: Uses non MMCSS priority 15, regardless of driver settings

MMCSS / Time Critical: Uses MMCSS priority 24, but only if MMCSS is disabled in RME drivers, else it falls back to non MMCSS priority 15. This looks like either a bug in Reaper or at least a conflict between Reaper and drivers that shouldn't happen.
from https://forum.rme-audio.de/viewtopic.php?id=17575

EDIT: forgot to mention - driver version 1.168, HW revision 48.
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Old 10-18-2019, 11:40 AM   #9
azslow3
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Quote:
Originally Posted by TabbyCat View Post
Which i7 is it? (2600, 6700, etc).

My Performance Meter reads .36ms / 1.33ms. This is a i9-7940x @ 3.10GHz, with Alicia Keys inside KK, slamming chords repeatedly. Buffer is at 64ms. Interface is RME Fireface UCX connected via USB.
Thank you for the reference numbers and extra information !

CPU is 6700. So it is a bit slower then your.

I have also not "optimized" it for audio, so no frequency lock/C states are enabled and all other BIOS power option on default. It is technically a bit tricky, I am far away from that computer.

I have measured up to 0.2ms system latency and up to 0.3ms general latency.
So we have checked one more time, we get stable under 0.7ms with Alicia. That is more or less in agreement with your results, assuming your system is audio optimized: 0.35ms + ~10% CPU performance difference + 0.3ms from sporadic system latency.

Changing RME setting and audio thread priority in REAPER have not produced any noticeable difference in our case.

We have sufficient safety for 64 samples / 44.1kHz mode now. So I have marked the thread as solved.

Thank you again for the input!
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