[LAD] 4-6 or 8 cores ??
Going to finally build a new machine. I'ts going to be Intel this time - AMD for 15 years or so - can any one here give some advice as to how many cores are optimal given current kernel >3.8 performance. Any install/operational issues? Any pitfalls ? any advice very welcome. cheers g. ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] 4-6 or 8 cores ??
Hi Geoff On Sun, 16 Jun 2013 20:49:26 +1000 you wrote: > Going to finally build a new machine. I'ts going to be Intel this time - > AMD for 15 years or so - can any one here give some advice as to how > many cores are optimal given current kernel >3.8 performance. Any > install/operational issues? Any pitfalls ? I can't provide much in the way of scientific evidence; there are others who know far more about the technical realities of this - and push their machines much harder - than I do. Personally, I have always run with the idea that so long as one has N independent processes whose links to other processes are limited to the consumption or production of streams, then one could theoretically max out N CPU cores. However in most practical cases involving audio and video one is running the streams at real world speed, and this obviously limits the extent that each process requires a CPU. The only time a single process would have the chance to max out a single CPU core would be when freewheeling with jack for example, or doing a final render of a video. If one spends most of the time interacting with their AV software, this means that there's no simple answer to the "how many cores are optimal" questions. It depends on the precise mix of software you're running, what each process requires of a CPU core, how much I/O each process instigates, and so on. Another caveat is jackd: my current understanding is that jack2 can better utilise multiple cores, but I'm happy to be corrected on this point by anyone with more knowledge than I (I really haven't looked into this recently because for my current situation it's academic). My system has been based on a first-generation i7 for the last couple of years and I've noticed no major issues. However, in terms of audio work I'm not really pushing the system all that hard during real work (I don't have soft-synths running generally, and the plugins I use tend to be fairly frugal with CPU requirements). This gives me 4 cores with hypertheading and when I've done tests to see what it could handle, an audio-like workload is able to push well above the 400% loading (so the hyperthreading seems to be doing something useful). Having said all that and knowing the sort of work you do, I would probably err on the side of getting as many cores as you can reasonably afford. As time goes on they won't go astray; you'll have the flexibility to experiment with new ways of doing things without being too constrained by the number of cores at your disposal. A final comment is that with the release of Intel's Haswell-based CPUs we are at an interesting point in time. These new cores are certainly a big win for mobile computing due to their lower power consumption for a given performance level. However, whether the increase in outright performance - the primary metric for a desktop - justifies the "new product" premium these will attract for the next 6-12 months remains to be seen, especially since one would also expect some runout discounting on the 4th generation CPUs in the coming months. Regards jonathan ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] 4-6 or 8 cores ??
On Sun, Jun 23, 2013 at 9:48 PM, Jonathan Woithe wrote: > Another caveat is jackd: my current understanding is that jack2 > can better utilise multiple cores, but I'm happy to be corrected on this > point by anyone with more knowledge than I > From https://github.com/jackaudio/jackaudio.github.com/wiki/Q_difference_jack1_jack2 "SMP support is not always as valuable as you would think. If your applications are chained INPUT --> A --> B --> C --> OUTPUT, then it will * not* be able to utilize multiple processors. However, if you applications are independently generating audio to the OUTPUT, that is when "parallel" sub-graph exist in the global graph, then they can be." ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] 4-6 or 8 cores ??
On Mon, 24 Jun 2013 03:48:21 +0200, Jonathan Woithe wrote: Having said all that and knowing the sort of work you do, I would probably err on the side of getting as many cores as you can reasonably afford. Strange, people claim that everything works without issues for old PCs, with one or two cores, even without a using a kernel-rt, so I would try to get such a machine that does everything that's needed, instead of getting more than is needed, not only to get less power consumption/heat/noise. IOW I wouldn't ask for the amount of cores, but for a setup that is known to run without xruns, jitter etc.. A Ferrari is much faster than a lorry, but would you prefer a Ferrari to a lorry for transporting band equipment? "Tuning" is for optimizing a system, not for having the "most" of what ever you can get. For me this request sounds like ... I want to buy a new amp. What's better 35 W or 150 W? I would ask ... I want to buy a new board/CPU and I own sound card Xyz. What mobo/CPU do you use with this card and are there any issues? 2 Cents, Ralf ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] 4-6 or 8 cores ??
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 On 2013-06-24 03:48, Jonathan Woithe wrote: > However in most practical cases involving audio and video one is > running the streams at real world speed, and this obviously limits > the extent that each process requires a CPU. The only time a > single process would have the chance to max out a single CPU core > would be when freewheeling with jack for example, or doing a final > render of a video. this very well matches my personal experience, that since the advent of PIII/800MHz i never had any more performance problems in my realtime applications. (theoretically this would hold true for a PI/100MHz as well, but alas, they don't make this stuff anymore). fgamsdr IOhannes -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.12 (GNU/Linux) Comment: Using GnuPG with Icedove - http://www.enigmail.net/ iEYEARECAAYFAlHIR24ACgkQkX2Xpv6ydvRpXACgkiifdry5f3GL9Q8ejRuXiz14 WRwAn2Wn7ikecYsvUR68Bf24bJguizCT =LcLR -END PGP SIGNATURE- ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
Re: [LAD] 4-6 or 8 cores ??
Le Mon, 24 Jun 2013 15:19:45 +0200, IOhannes m zmoelnig a écrit : > his very well matches my personal experience, that since the advent > of PIII/800MHz i never had any more performance problems in my > realtime applications. For me, a multi-cores machine is a must. In one hand, jack1 on a 32 bits single core machine and a rt kernel, give me very little less latency, than jack2 on a 64 bits 4 cores machine and a "regular" kernel, with rt enabled via cgroups. Both machines have the maximum amount of RAM they can handle and are running fvwm-crystal as desktop. On the other hand, this last machine give me the opportunity to be able to do whatever I want, as example run a server, have emerge that compile hugin or libreoffice, and run rt applications, all that at the same time on the same machine. To do the same with a single core machine, I must have a double boot with 2 kernels, a rt one for the audio applications, and a non rt one for the server and emerge (I don't try it with a cgroup enabled kernel). Dominique -- "We have the heroes we deserve." ___ Linux-audio-dev mailing list Linux-audio-dev@lists.linuxaudio.org http://lists.linuxaudio.org/listinfo/linux-audio-dev
