/srv/irclogs.ubuntu.com/2022/02/22/#ubuntustudio.txt

BrianHechinger[mOvenWerks: did we ever prove the AudioFire 4 and 12 were different hardware? I can't get the 4 to anywhere near 16/2.10:20
OvenWerksIamthehuman12: I have no way of knowing that. I would expect the FW chipset part to be the same, the mixer to be the same but maybe fewer chips, the adc/dac and audio stuff might be different (like the delta 44/66 as compared to the delta 1010 (or the d1010lt) they all used the same base chip but the adc/dac and audio are different qualities15:56
OvenWerksIamthehuman12: sorry wrong nick... BrianHechinger[m ^^^16:15
OvenWerksBrianHechinger[m: there is much more to low latency than just the audio device. or even the audio device and the PCIe card it connects to.16:16
OvenWerksI think we are both using the same kernel as well.16:17
OvenWerksAt the time I put this computer together (I guess it is old now) Audio was my first concern. My previous experiance (P4 days) had shown me that hyperthreading caused trouble below 64/2 (sometimes even at) and so I decided the i5 with 4 cores and 4 threads would be the best chip. no use paying for the i7 and shutting half of it down.16:21
OvenWerksBrianHechinger[m: I think that both hyperthreading has improved and the way linux deals with hyperthread cores has improved, but I have not been able to test that on my i5 :)16:22
OvenWerksBrianHechinger[m: once I had the chip I wanted to use, I went through the motherboards that chip would fit in (that had the right socket). I found that the most expensive ones had a lot of bells and whistles on board and I was concerned that they would use up IRQs or other resources, also the audio card I was using at the time was a set of two PCI (not PCIe) cards and so I wanted maximum number of 16:27
OvenWerksPCI slots. This meant look for a full size board (7slots) and I was able to find one with 3 PCI slots for my two PCI boards16:27
OvenWerksI found this just below about the middle of the available MBs. Of course one of those PCI slots used the dreaded IRQ16, shared with a number of other things and was not usable. (PCIe is different usng virtual IRQs)16:30
OvenWerksBrianHechinger[m: I have of course tuned the IRQs, made sure my cores always run at one speed, stop cron if need be, etc.16:36
OvenWerksBrianHechinger[m: other than these things I do not know how our systems might differ. If you can at least start jack at 16/2, that would argue for the chipset in the device being the same. If jack will not even start with such a low latency and hangs instead that may be a different matter16:38
BrianHechinger[mYeah, the fact that I can't even start jack below like 64/3 or whatever it is really bothers me. I should be able to start at 16/2 even if it's a trainwreck of xruns17:16
BrianHechinger[mI found with liquorix I could start 16/2 just fine, but that doesn't have threadedirq enabled (it clashes with their choice of scheduler) so I'm still not sure what that proved. Liquorix also had some nasty instabilities on my system so it's been purged.17:17
BrianHechinger[mI'm mostly just trying to wait for 22.04 at this point because I figure the best time to really rattle trash cans is on an LTS release and not an interim one.17:17
BrianHechinger[mOvenWerks: The other thing to keep in mind was early hyperthreading was bad. Really bad. to the point where we turned it off on all the servers and got better performance (out of both windows and linux)17:22
OvenWerksBrianHechinger[m: yes I realize early HT was some of the worst. However, even if it is better now, if the core makes a context change at the wrong time, it will affect minimum scheduling. maybe not at 64/2 but getting things down to less than 1ms that is more iffy.17:59
OvenWerksI think newer kernels are smart enough not allow low priority threads to use the same core though.18:00
BrianHechinger[mYeah, that's probably true. An interesting experiment would be to exclude a core from doing any other work and dedicating it to the low priority stuff. But, until i can get Jack starting at all with lower latency it's kinda moot. 😜18:09
EickmeyerThe 5.15 kernel in Jammy has some nice RT improvements, so keep that in mind.19:15
BrianHechinger[mYeah, that's another reason why I'm waiting for 22.04 to start really digging into this again.21:52
OvenWerksHmm, I should try running 16/2 then... I had two xruns pretty quick after I started. But it's fine now. DSP is 12 to 15% with youtube running through it.22:01
OvenWerkshmm I've had better, 20ish xruns in 8 minutes22:08
OvenWerksStill, I don't need 16/2 and 64/2 runs forever still.22:09

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