By: anon (spam.delete.delete@this.this.spam.com), August 10, 2019 1:58 pm
Room: Moderated Discussions
Linus Torvalds (torvalds.delete@this.linux-foundation.org) on August 10, 2019 12:13 pm wrote:
> anon (spam.delete.delete@this.this.spam.com) on August 10, 2019 11:25 am wrote:
> >
> > If Linus is interested in the 3950X as an upgrade and not the 3900X (or even 3800X) I
> > highly doubt it's for the single thread performance.
>
> I'm a big proponent of single-thread performance in general, because a lot
> of real-world problems really do end up being fairly limited by Amdahl.
>
> So you'll find me often talking up single-core performance,
> and I absolutely despise the "flock of chickens" machines.
>
> But realistically, Zen 2 is clearly in the "good enough" territory for anything I do on that front.
> It will open that huge pdf file without me twiddling my thumbs, even when that's almost entirely
> single-threaded. And once something performs well enough, all that I really do is build the kernel.
> Which is actually ludicrously well parallelized - more so than most other projects are.
>
> So I think single-thread performance is king, but I also know that the only thing I personally do
> doesn't really care all that deeply. We've got a couple of link stages and a few other serialized parts,
> but the really expensive parts when I do a full re-build can easily use hundreds of cores.
>
> I just don't think that because I can use hundreds of cores that that
> is necessarily a good fit for a lot of other real-life problems.
>
> From a performance standpoint I could easily use server-class machines (or something like Threadripper).
> Or even a farm. It's just that I also want it to be quiet and a convenient form factor, and easily
> available. If I can't buy the parts at the local Fry's or with two-day shipping off Amazon, I'm
> just not interested. You can keep your bespoke stuff. I believe in mass market.
>
> Linus
Yeah, I could guess the reasoning and you did mention the TDP and wanting a quiet machine.
This was just for john. No one upgrades from an 8 core to a 16 core with virtually identical or worse single threaded performance if higher single threaded performance is their top priority and an 8 or 10 core would do.
Zen 2 in general is looking quite interesting for upgrades. I never cared for "enthusiast" platforms. I don't need the extra memory channels and I certainly don't feel the need to pay 2000$ for a CPU to get a few extra cores even though I could. But 330$ for 8 cores with SMT or 500$ for 12 is quite fair and quite tempting. And you don't feel like you're losing anything in ST like with Zen 1. 750$ for 16 cores isn't bad either even though I don't really "need" it, but should I wait that long until I actually upgrade I might as well, right?
Either way recently it has been a lot more interesting than "still 4 cores, still ~300$, just slightly faster" we've had for a decade. Now upgrades feel worthwhile again.
> anon (spam.delete.delete@this.this.spam.com) on August 10, 2019 11:25 am wrote:
> >
> > If Linus is interested in the 3950X as an upgrade and not the 3900X (or even 3800X) I
> > highly doubt it's for the single thread performance.
>
> I'm a big proponent of single-thread performance in general, because a lot
> of real-world problems really do end up being fairly limited by Amdahl.
>
> So you'll find me often talking up single-core performance,
> and I absolutely despise the "flock of chickens" machines.
>
> But realistically, Zen 2 is clearly in the "good enough" territory for anything I do on that front.
> It will open that huge pdf file without me twiddling my thumbs, even when that's almost entirely
> single-threaded. And once something performs well enough, all that I really do is build the kernel.
> Which is actually ludicrously well parallelized - more so than most other projects are.
>
> So I think single-thread performance is king, but I also know that the only thing I personally do
> doesn't really care all that deeply. We've got a couple of link stages and a few other serialized parts,
> but the really expensive parts when I do a full re-build can easily use hundreds of cores.
>
> I just don't think that because I can use hundreds of cores that that
> is necessarily a good fit for a lot of other real-life problems.
>
> From a performance standpoint I could easily use server-class machines (or something like Threadripper).
> Or even a farm. It's just that I also want it to be quiet and a convenient form factor, and easily
> available. If I can't buy the parts at the local Fry's or with two-day shipping off Amazon, I'm
> just not interested. You can keep your bespoke stuff. I believe in mass market.
>
> Linus
Yeah, I could guess the reasoning and you did mention the TDP and wanting a quiet machine.
This was just for john. No one upgrades from an 8 core to a 16 core with virtually identical or worse single threaded performance if higher single threaded performance is their top priority and an 8 or 10 core would do.
Zen 2 in general is looking quite interesting for upgrades. I never cared for "enthusiast" platforms. I don't need the extra memory channels and I certainly don't feel the need to pay 2000$ for a CPU to get a few extra cores even though I could. But 330$ for 8 cores with SMT or 500$ for 12 is quite fair and quite tempting. And you don't feel like you're losing anything in ST like with Zen 1. 750$ for 16 cores isn't bad either even though I don't really "need" it, but should I wait that long until I actually upgrade I might as well, right?
Either way recently it has been a lot more interesting than "still 4 cores, still ~300$, just slightly faster" we've had for a decade. Now upgrades feel worthwhile again.