i recently upgraded from my old quad core q9550 with 4 GB SSD 2 RAM to a dual xeon e5 2670 (2x8 core) with 32 GB DDR 3 RAM,
the performance on the quad was very good, and audio was mainly not the reason for my upgrade, but now i have performance lags all over
with the exact same setup, where cpu usage normally would be around 20%, it skips up to around 60-75$ and audio is stuttering…
in renoise (2.0), all 16 cores are selected, (in bios, i have deactivated hyperthreading), and no matter if i switch down to 8 or 4 cores and click reinitialize,
the processor usage remains the same when playing an audio track with exactly the same plug ins …
in addition, when rendering out in 24 bit or 32 bit, it is 30-40% slower than the old quad core… wen i verify the core usage through hardware monitor, it shows that only 1 or 2 cores are fully used,
most are at 0%, some at 3%, some at 17%… how can that be? and how can an 8 times faster pc be slower, especially considering an SSD instead of the old, slow HDD is used?
Renoise is not like raytracing, video rendering, or data folding. It will split stuff to run in parallel very rough. Audio graphs are not simple to just chop into pieces and evenly spread among cpus. This is for realtime, and also for rendering which is basically like realtime but without waiting for the clock/soundcard until it is time for the next block of audio. I have 6core and it seems it need lots of tracks and instruments independent from each other to take use of the power. But I can’t tell for sure, as renoise will only present one number, and no way to judge how well it is putting stuff into parallel operation.
For the general perfomance stuff. I think I remember multi cpu setups is not so much like having the double amount of cores, but rather a bit like a network (via ram bus/sharing) of 2 pcs. So syncronisation between the cpus is much slower than it would between to cores of the same chip that share a fast cache. And it has to be addressed in the software and the operating system to be properly utilised. Maybe you could try to disable a whole cpu in bios for a test if it is possible? I could imagine renoise just wasn’t written with multi cpu systems in mind and suffers from trying to sync threads via the slower connection between two cpus. Also I know of no similar realtime application to run across “networks” of cpus, only stuff like raytracing or data folding/crunching. Or maybe utilising virtualisation and reserving cpus for isolated realtime tasks.
What os do you use? On windows, you should check your system for dpc latency. Bad drivers can cause huge dpc latencies, which causing bad audio performance. What audio driver do you use?
I repeat in short words: a 2 cpu 2x8 cores machine won’t work the same as a single cpu 16 core machine. Software that was never optimized to run on multi cpu machines might cause problems.
Try to disable one cpu, or lock everything that has to do with renoise to a single cpu on operating system level, and see if things get better.
I know it is sad news. You will be able to rock stuff like graphics raytracing with the machine in full potential. But not realtime audio like renoise - spreading such a program across the 2 cpus will limit performance.
