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Single core versus Multicore CPU

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Re: Single core versus Multicore CPU

Postby resistorman » Tue Dec 03, 2019 7:16 am

Single core FUD is being promoted by Intel since AMD is cleaning their clocks with multi core. Quite the reversal from the Athlon vs Core days.
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Re: Single core versus Multicore CPU

Postby Pete Kaine » Tue Dec 03, 2019 12:10 pm

JacoVanDuijn wrote:I have always thought that Multi-core CPU's where better (for Video editing, etc everything non-gaming related) for audio production. But I read that single core performance is better.

Which one is true?

Yes.

JacoVanDuijn wrote:And are their DAWS out there that make use of multi-core? (I read that in the new studio one 4.5 they support multi-core, but not how many. I wanted to ask this on the presonus forums, but I don't have Studio one to register).

Ok, so all DAW's have multi-core support and they are all core limited to some degree. I'd say thread limited, but as Eddy's already pointed out the true meaning of a thread is rather different from Intel or AMD's public facing definition which in reality is really what the rest of the world calls "Logical Cores" (as opposed to "Physical Cores").

I don't think there are any DAW's left out there that handle less than 48 LC's at this point and I suspect most will do a fairly standard 64 with a few more being able to be pushed higher, although I've seen perfomance start to deteriorate once I've gone beyond the 64 LC figure, so if anything I'd imagine the artifical constraints are to do with load balance managment although I suspect there are better people in this thread to comment upon that.

JacoVanDuijn wrote:I am about to buy a new pc and really don't know what to get. I was first going for the Ryzen 3950x, untill I read about the importance of single core performance.

Well, it's IPC (instructions per clock) that is key, or more to the point how accessible they are. You can have two chips with 4GHz core clocks, but the IPC on one might be twice as high as the other, so those two chips wouldn't be all that comparable this is the difference between an i7 first and tenth gen or a AMD first and third generation setup (figures pulled from thin air for point of the example).

Turbos can be miss-leading and the CPU to some degree is only as good as the weakest core.

They tend to stagger turbos, with one or two cores at the full figure and then each additional core being staggered by a 100MHz or 200MHz all the way down to that base clock. What this means is that if all cores are equally loaded, then it will start to lose data (discard and glitch the audio) when the slowest core runs out of overhead.

Of course, the system will try and balance it so that the weaker loads are on the slower cores in an attempt to get the most from the setup. Where this becomes tricky is that you tend to see the entire channel and even dependent tracks get processed on the same core in large chains. Maybe not such a great concern if your mixing in a more traditional sense of taking audio tracks and processing away, but the generation of audio in the box and the processing chains that get applied mean that you sometimes need to keep a careful eye on what a single core might be doing least it get bit overly demanding.

I've long been an advocate of trying to level the cores off where possible. My preference this is done around the single core turbo speed, but we'd raise the rest to match it and for instance with a 9900K we push all cores to 4.9GHz rather than just one of them.

Of course you can't always do this with every chip range as tolerances change between designs and the interesting one (well, headache inducing one in my case) has been trying to figure out where AMD stands on this.

They've been advising for a while now that RAM optimization is better for the end user than overclocking in any way and I agree, I got similar performance results out of overclocking and optimizing the RAM in recent testing, as I did out of overclocking the CPU to an inch of it's life, which means I didn't have to overclock the CPU and the voltages I cranked for that overclock could be removed and the chip now runs a lot cooler which of course is a great. The upshot of this is that you can either run slow RAM and overclock or your can run fast RAM and not overclock.

So, this means whilst we now have a cooler chip, we also open up the chances of it running out of performance earlier on a single core. In real terms through there is enough RAW performance through the extra cores that it more than makes up for this as a balance.

To note, AMD has come under fire for being able to rarely hit their advised turbo figures, with constant updates appearing to tweak it. Instead the 3950X for example (because it's fresh in my mind) has a 3.5GHz base clock and 4.7GHz advised turbo and in my own testing we're looking at it only managing to hit around 4.1GHz - 4.25GHz across the various cores. The interesting thing for me was that none of the cores were spiking under DAW usage (whereas they might with a program that favours single cores) and this is how I would prefer a CPU to behave when dealing with a hugely multi-core capable client and audio.

As a general example I would take a 12 core 4.2GHz over a 8 core 4.6GHz.
But I would most likely take a 8 core 4.6GHz over a 12 core 3.8Ghz

All depending on the generational IPC scores of course.

Eddy Deegan wrote:
JacoVanDuijn wrote:I have always thought that Multi-core CPU's where better (for Video editing, etc everything non-gaming related) for audio production. But I read that single core performance is better.

Are you sure you read that right? There may be advice out there to disable hyper-threading on certain Intel CPUs due to the issues associated with the various CPU hardware bugs that surfaced a while back but generally speaking more cores is better when it comes to video editing.

Video editing is largely off-line rendering and the CPU is able to just deal with it as and when it can free up the processing capability. More cores the better and we're not overly bothered by how fast they are (more is more through)

Audio (and to be be fair, video streaming) is real-time and so you either complete the work within a given cycle (i.e. your ASIO buffer) or you can expect drop outs and glitching to ruin your session.

miN2 wrote:Re Studio One: it supports multi-core, but they took serious time implementing it to a half-way decent standard in my view, and it still doesn't really hold a candle to the likes of Cakewalk and Cubase.

Studio One 3 by all accounts was pretty well put together, but from feedback the Studio One 4 engine managed to go backwards to some degree when they made changes under the hood. Apparently they've improved it again in recent build releases, so I'm a little bit lost to how exactly it holds up these days, although good to know they've been working on it.

merlyn wrote:The R9 3900x looks good with a slightly faster base clock of 3.8 GHz versus the 3.5 GHz of the 3950x.

The 3900X is marginally faster per core on average, but again we're talking about the system running a roughly 4.2 - 4.3 average across those cores under heavy loads. The small 100MHz difference for me puts the 3950X ahead on it's higher core count.

To anyone wondering why I've not published the 3950X yet, stock has been really lacking and I only got to play with one last week. I don't normally cover limited editions (hence no 9900KS coverage) and AMD isn't letting on if they are shipping any more stock anytime soon or at all. I'll more than likely cover it when I do the Intel 10 series, although they also don't have stock, but at least they can outline a figure of at last double digits when asked how many we might see over.
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Re: Single core versus Multicore CPU

Postby Folderol » Tue Dec 03, 2019 12:47 pm

As a point of interest, a certain soft-synth of my acquaintance has 1 very high priority audio thread, 1 slightly lower priority MIDI thread, and 3 very low priority UI and housekeeping threads.

In Folderol towers, on a single core machine it runs like a pig. On a dual core one it runs well. On a 4 core one it runs extremely well. The 4 core machine runs at the same clock speed as the 2 core one (neither overclocked).
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Re: Single core versus Multicore CPU

Postby JacoVanDuijn » Sat Dec 07, 2019 5:12 pm

Pete Kaine wrote:
To anyone wondering why I've not published the 3950X yet, stock has been really lacking and I only got to play with one last week. I don't normally cover limited editions (hence no 9900KS coverage) and AMD isn't letting on if they are shipping any more stock anytime soon or at all. I'll more than likely cover it when I do the Intel 10 series, although they also don't have stock, but at least they can outline a figure of at last double digits when asked how many we might see over.

Dear Pete,

thank you for taking the time and writing all of this. I have learned so much from you and others here.

1. Let's say I would get a good SSD, good and fast ram etc, so no bottlenecks and I have the money should I go for the 3950x? My aim is to decrease stutter and crackling. Will the 3950x be the best option of all the cpu's out there or would you advice a different CPU?

2. You also talked about real-time. is it true that real-time processing is done better with more cores (again, assuming no bottlenecks from other PC parts)?
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Re: Single core versus Multicore CPU

Postby Pete Kaine » Mon Dec 09, 2019 11:46 am

JacoVanDuijn wrote:1. Let's say I would get a good SSD, good and fast ram etc, so no bottlenecks and I have the money should I go for the 3950x? My aim is to decrease stutter and crackling. Will the 3950x be the best option of all the cpu's out there or would you advice a different CPU?

Ideally, you need to pick your price point before asking that question. It's not the best out there, but it's probably the best bang per buck currently.


JacoVanDuijn wrote:2. You also talked about real-time. is it true that real-time processing is done better with more cores (again, assuming no bottlenecks from other PC parts)?

No, single core score tends to be more important and then number of cores for real-time handling and you more than likely be better served taking 8 cores at 4.2GHz over 16 cores at 2.4Ghz for instance.
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Re: Single core versus Multicore CPU

Postby CS70 » Mon Dec 09, 2019 12:11 pm

JacoVanDuijn wrote:2. You also talked about real-time. is it true that real-time processing is done better with more cores (again, assuming no bottlenecks from other PC parts)?

A little point of pedantry - you don't have real "real time processing" in a system unless the operating system (and to a degree the hardware) is "real time" (regular Windows and OSX aren't): true "real time" processing means guaranteed processing time - and since the time-quality-price triangle is valid for CPUs as well :) , the implication is that in a real time system the same computation is not guaranteed to provide the same result every time. In practice you will get whatever state of the computation exists when the deadline (the time allocated to the operation) expires - and this specific kind of interruption must generally be implemented at very low level, in hardware.

General purpose operating systems prioritize correctness of result over time guarantees, and at most provide an estimate of execution time for a given computational load. Of course we use "real time" loosely to indicate that the system is fast enough in the most cases. In practice, under a load which is easy to handle by the resources available (cores, bandwidth, local memory etc), a non RT OS will in average work fast enough to make little difference, but all the personal computers we use tend to be of that sort.
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Re: Single core versus Multicore CPU

Postby wireman » Mon Dec 09, 2019 9:08 pm

CS70 wrote:General purpose operating systems prioritize correctness of result over time guarantees, and at most provide an estimate of execution time for a given computational load. .

Really? I think they prioritise fair access to resources (for some measure of fair) for a running workload.
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Re: Single core versus Multicore CPU

Postby CS70 » Mon Dec 09, 2019 9:50 pm

wireman wrote:
CS70 wrote:General purpose operating systems prioritize correctness of result over time guarantees, and at most provide an estimate of execution time for a given computational load. .

Really? I think they prioritise fair access to resources (for some measure of fair) for a running workload.

It's a different level of abstraction. Fair access to resources, for whatever definition of "fair", can be provided by both real time and non real time systems - it's only a matter of load distribution. Both models allow for preemptive scheduling of computational flows.

But the defining characteristic of "correctness"-oriented system is that the flow of control does not return until a computation is completed, regardless how much time it takes. 2+2 is always 4, but it may take a potentially unbounded while for the result to be computed and the flow of control returned to tthe requester.

A "true" realtime system, on the other side, works with strict deadlines: if the allocated time for the computation is expired the flow of control and the result is returned (possibly with a flag set). So 2+2 occasionally maybe 3.5 or whatever.

This may seem odd but typically in physical control systems is much better to have an occasionally slightly wrong result than a possibly long waiting time before the computation is finished. This is also occasionally useful for algorithms which return quickly most of the time but may behave different for a few sets of input parameters, etc.

Obviously a real time system must be sized so that the majority of the expected computations do not generate errors.. and that's why it's not so suited for general purpose computers. Both models have equivalent computational power and you can emulate one with the other but when implemented in a physical machine, you've gotta choose.
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Re: Single core versus Multicore CPU

Postby wireman » Mon Dec 09, 2019 10:21 pm

CS70 wrote:
wireman wrote:
CS70 wrote:General purpose operating systems prioritize correctness of result over time guarantees, and at most provide an estimate of execution time for a given computational load. .

Really? I think they prioritise fair access to resources (for some measure of fair) for a running workload.

It's a different level of abstraction. Fair access to resources, for whatever definition of "fair", can be provided by both real time and non real time systems - it's only a matter of load distribution. Both models allow for preemptive scheduling of computational flows.

But the defining characteristic of "correctness"-oriented system is that the flow of control does not return until a computation is completed, regardless how much time it takes. 2+2 is always 4, but it may take a potentially unbounded while for the result to be computed and the flow of control returned to tthe requester.

A "true" realtime system, on the other side, works with strict deadlines: if the allocated time for the computation is expired the flow of control and the result is returned (possibly with a flag set). So 2+2 occasionally maybe 3.5 or whatever.

OK, yes. For some reason when I read the post I thought you meant that a general purpose OS could choose how much priority to place on correctness.
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Re: Single core versus Multicore CPU

Postby CS70 » Tue Dec 10, 2019 12:54 am

wireman wrote:
OK, yes. For some reason when I read the post I thought you meant that a general purpose OS could choose how much priority to place on correctness.

All good, no stress.
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Re: Single core versus Multicore CPU

Postby LoveMonkey3833 » Tue Dec 10, 2019 8:52 am

merlyn wrote:
miN2 wrote:Turbo boost requires sufficient power and cooling available to maintain the boost. If the system has this is can be maintained indefinitely.

Would a stock cooler do that?

What chip would you go for? Out of the high end choices on this thread I'd go for a Ryzen 3900x because it has speed and cores.

@JacoVanDujin Put simply clock speed gives low latency and more plugins on one track. More cores gives more tracks or virtual instruments.

DO NOT USE A STOCK COOLER!!!!!
Get a Noctua DH-15 cooler with Kingpin cooling paste! Mixing and doing audio work makes your computer hot as it maxes everything out! Stick with air cooling as it's easier and tbh most water coolers that you buy off the shelf still don't stand up to Noctua's top of the line air cooler the NH-D15. It's the best air cooler in the biz. There are 2 that come close right now, maybe 3, but still can't beat it. Also get a case that has great air cooling, but isn't crazy loud! Like Rosewill Thor V2! Nothing beat's it that I've come across yet!
Make sure you've got a great PSU as well, like an Evga Supernova G2 1300. People will tell you to get maybe a 650 PSU or some bs like that, but don't take into account all the crap we have to install in the computer, plus all the peripherals we run off of USB hubs, plus the addon's we might put on later! Get an overpowered PSU, and make sure it's at least Gold standard, and it has a 10year warranty. You don't want your thousands of dollars setup to take a dump on you and blow up your shit! Trust me it's not worth it. Had a Rosewill PSU that literally blew up my AMD build back in say 2010 or so. Their PSU's suck, but cases are great! Also, get extra fans for your case, yes this case is the only one that comes with a huge ass 280mm fan(or something like that)on the side blowing directly onto your CPU, but you still want extra fans in there! I'd get Noctua fan's or Arctic fan's or whoever bought out Scythe....them guys. Really I'd skip Artic and just go Noctua or the Scythe wannabe guys. Cooling is super important! VERY VERY VERY Important! If that didn't sink in, let me say it again in caps....COOLING IS VERY IMPORTANT!
Oh and the AMD 8650 (or whatever number it is)on all the tests smoked the Intel CPU's. But In my experience AMD CPU's suck ass when it comes to audio processing. Maybe the new ones are killer, but until I got concrete evidence I stuck with Intel. Recently upgraded my cpu from a 6 core 5820k to a 9700k. I wanted to go with the I9 but couldn't afford it since I'm building from scratch. Didn't have the extra $227$ to throw on a cpu with marginal improvements. Of course, they were out of the AMD ones the 50's whatever number they are. But I wanted Thunderbolt compatibility and the Gigabyte Z390 Designare board was the only one proven to be compatible with UAD's Thunderbolt. AMD didn't have any boards that were "proven" to be working on Thunderbolt without issue on a Windows-based machine. Now that may have changed in the last 2 weeks since I did my research, or I may have missed it, but still, Intel has traditionally been better for audio production. But I totally hate that since I think they are too damn expensive for what you get and would rather have 12 cores that are faster with AMD....and generally cheaper too. Alas, it wasn't meant to be, and I probably should be grateful because my experience with AMD as audio production workstations is absolutely terrible. Nothing but issues at every turn! Although I would recommend an AMD GPU instead of Nvidea for your audio production CPU as there are a few articles of how AMD beats Nvidea somehow for audio production computers. You'll have to google it as I'm too lazy right now to find it!
My recent build is an Intel 9700k I7, Noctua NH-D15 Chromax cooler, Corsair Vengence LPX 3200 ram, AMD Sapphire 590x GPU(the blue one) got it open box for $160 at Microcenter, an Adata-3000 write speed or so nvme SSD drive(don't remember the numbers was $100 on sale though), Gigabyte Z390 Designare mobo, Evga Supernova G2 1300 PSU, Rosewill Thor V2 case, and about 7 additional Noctua fans in there. All of it was overclocked to 4.9 and the ram was as well, but a buddy did that for me and made it so that I could do change from normal function to overclocked audio production function from my desktop after a restart. So if I'm not working on a crazy large project I don't have to worry about it getting crazy hot in there, although my cooling is pretty wicked good for not going the water route. Oh and all my fans including my cpu cooling fan is hooked up to 2 rotary dials on the front of my case so that while recording I can turn down the fans, and then crank them when mixing! They can get loud when cranked even though I got quiet fans, nothing you can do about moving that much air. Think of jet's pushing tonnes of air....Not the same but you can't make it dead quiet either no matter what you do. Only mitigate it. Buy buying a case like a Be Quite case with soundproofing in the case, you'd have to go with water cooling as not enough air would be able to get in the case otherwise! Good luck on your build!
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Re: Single core versus Multicore CPU

Postby Pete Kaine » Tue Dec 10, 2019 10:41 am

CS70 wrote:A "true" realtime system, on the other side, works with strict deadlines: if the allocated time for the computation is expired the flow of control and the result is returned (possibly with a flag set). So 2+2 occasionally maybe 3.5 or whatever.

Aye, it's for want of a better term really. Given ASIO is buffer based, it's not quite real time of course, although in contrast expired time in this context results in data errors manifesting as currupted audio whilst still continuing to otherwise process as normal.

It's a far cry from a off-line job through as the demands remain different, we need an intermedite term for it.
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Re: Single core versus Multicore CPU

Postby James Perrett » Tue Dec 10, 2019 3:52 pm

Pete Kaine wrote:It's a far cry from a off-line job through as the demands remain different, we need an intermedite term for it.

Back in the days when I was dealing with real time operating systems (like VxWorks or VRTX) we would talk about hard real time systems and soft real time systems. The word 'deterministic' seemed to crop up quite a bit too.
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Re: Single core versus Multicore CPU

Postby CS70 » Tue Dec 10, 2019 4:03 pm

Pete Kaine wrote:
CS70 wrote:A "true" realtime system, on the other side, works with strict deadlines: if the allocated time for the computation is expired the flow of control and the result is returned (possibly with a flag set). So 2+2 occasionally maybe 3.5 or whatever.

Aye, it's for want of a better term really. Given ASIO is buffer based, it's not quite real time of course, although in contrast expired time in this context results in data errors manifesting as currupted audio whilst still continuing to otherwise process as normal.

It's a far cry from a off-line job through as the demands remain different, we need an intermedite term for it.

No worries, I was just being pedantic because it was a good opportunity to shed some light on a computer science idea which is not widely understood. I use myself "real time" in the same context, because as you say the context makes clear what one means..
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