3 ms·

We all know that a single core with twice the performance and twice the cache space is generally better than two cores (though a sibling comment does raise a go

by gpm 7y ago

We all know that a single core with twice the performance and twice the cache space is generally better than two cores (though a sibling comment does raise a good point that poorly written software can lock up an entire core regardless of it's Hz, also some VM scenarios would prefer extra cores over faster cores). We also all know that a single core with twice the performance and twice the cache space costs a lot more than two cores. It's a lot more expensive than even 3 cores. I'd rather have 3 4Ghz cores than 1 8Ghz core (except for the novelty value).

yjftsjthsd-h 7y ago
We all know that a single core with twice the performance and twice the cache space is generally better than two cores I'm not sure that's actually true, even if you want performance (although it's dependent on whether your workload can use more than 1 thread, of course): A single core at a higher clock speed might be better if it can hold that clock speed. But the faster you run, the more power you use and the more heat you produce, and worse, the relationship isn't linear. So ex. 1 core at 4ghz won't stay at 4 ghz, where 2 cores at 2 ghz can hold that speed forever.
- gpm 7y ago
  Right, when I say an xGhz core I'm pretending to live in a simpler world where they can all hold that speed forever. Consider an 8Ghz core to be a core + cooling that can consistently hold a speed twice as fast as the 4Ghz core + cooling can hold.
globular-toast 7y ago
> We also all know that a single core with twice the performance and twice the cache space costs a lot more than two cores. It's a lot more expensive than even 3 cores. I'm a programmer, I don't care how much it costs the hardware manufacturer. I want a single core. Multi-threaded programming sucks. I don't care if that's implemented via multiple cores acting together and only presents itself as a single core. I just want a single core. > I'd rather have 3 4Ghz cores than 1 8Ghz core (except for the novelty value). I'd much rather avoid multi-threaded programming and get the 8GHz core. But your comment is missing the point, really, which is that single-core performance matters. If the 8GHz core existed then you'd still be able to get 3 8GHz cores. Still want the 3x4GHz?
- gpm 7y ago
  8Ghz cores do exist if you have enough money to hire someone to deal with the overclocking for you (or enough liquid nitrogen and time to do it yourself). I, on the other hand, care about the cost of my computers a bit more than that, not having infinite money. Which is why even if 8Ghz cores were commercially available I suspect I would still be buying 3 times as many 4Ghz ones.
  - blattimwind 7y ago
    A Bulldozer FX barreling down the highway at over 8 GHz is actually still slower than any modern CPU at less than half the clock speed. The latter also doesn't require LN2 cooling and doesn't draw more than 100 W for a single core.
- zrm 7y ago
  > If the 8GHz core existed then you'd still be able to get 3 8GHz cores. Well no. Right now you can get ~5GHz cores and they draw close to 300 watts per core, which is why they can't run all cores at 5GHz on threaded programs. For the same amount of power as one core at 5GHz you can get 64 cores at almost 3GHz, e.g. ThreadRipper 3990X. An 8GHz core would presumably draw 500+ watts per core and maybe even a lot more than that. To get the same performance as the 3990X, you would either need a single 185GHz core (basically impossible) or >23 8GHz cores (expected power draw >11kW). That would cost thousands a year in electricity, but a normal 20 amp household circuit breaker would trip before you hit 2.5kW anyway. More than that, by the time you write code that can scale to 16+ threads, 64 isn't that much harder, and 256 isn't much harder than that. So get used to it, because in a few years there are going to be 256-core mobile devices and 1024+ core desktops and servers.
  - p1necone 7y ago
    globular-toast seems to be arguing past everyone because they're imagining a reality where a. these hypothetical ultra high clocked single core CPUs actually exist, and b. they have unlimited spending money and don't care at all about power usage or cooling.
- 7y ago

by gpm 7y ago

yjftsjthsd-h 7y ago

We all know that a single core with twice the performance and twice the cache space is generally better than two cores I'm not sure that's actually true, even if you want performance (although it's dependent on whether your workload can use more than 1 thread, of course): A single core at a higher clock speed might be better if it can hold that clock speed. But the faster you run, the more power you use and the more heat you produce, and worse, the relationship isn't linear. So ex. 1 core at 4ghz won't stay at 4 ghz, where 2 cores at 2 ghz can hold that speed forever.

gpm 7y ago
Right, when I say an xGhz core I'm pretending to live in a simpler world where they can all hold that speed forever. Consider an 8Ghz core to be a core + cooling that can consistently hold a speed twice as fast as the 4Ghz core + cooling can hold.

globular-toast 7y ago

> We also all know that a single core with twice the performance and twice the cache space costs a lot more than two cores. It's a lot more expensive than even 3 cores. I'm a programmer, I don't care how much it costs the hardware manufacturer. I want a single core. Multi-threaded programming sucks. I don't care if that's implemented via multiple cores acting together and only presents itself as a single core. I just want a single core. > I'd rather have 3 4Ghz cores than 1 8Ghz core (except for the novelty value). I'd much rather avoid multi-threaded programming and get the 8GHz core. But your comment is missing the point, really, which is that single-core performance matters. If the 8GHz core existed then you'd still be able to get 3 8GHz cores. Still want the 3x4GHz?

gpm 7y ago
8Ghz cores do exist if you have enough money to hire someone to deal with the overclocking for you (or enough liquid nitrogen and time to do it yourself). I, on the other hand, care about the cost of my computers a bit more than that, not having infinite money. Which is why even if 8Ghz cores were commercially available I suspect I would still be buying 3 times as many 4Ghz ones.
- blattimwind 7y ago
  A Bulldozer FX barreling down the highway at over 8 GHz is actually still slower than any modern CPU at less than half the clock speed. The latter also doesn't require LN2 cooling and doesn't draw more than 100 W for a single core.
zrm 7y ago
> If the 8GHz core existed then you'd still be able to get 3 8GHz cores. Well no. Right now you can get ~5GHz cores and they draw close to 300 watts per core, which is why they can't run all cores at 5GHz on threaded programs. For the same amount of power as one core at 5GHz you can get 64 cores at almost 3GHz, e.g. ThreadRipper 3990X. An 8GHz core would presumably draw 500+ watts per core and maybe even a lot more than that. To get the same performance as the 3990X, you would either need a single 185GHz core (basically impossible) or >23 8GHz cores (expected power draw >11kW). That would cost thousands a year in electricity, but a normal 20 amp household circuit breaker would trip before you hit 2.5kW anyway. More than that, by the time you write code that can scale to 16+ threads, 64 isn't that much harder, and 256 isn't much harder than that. So get used to it, because in a few years there are going to be 256-core mobile devices and 1024+ core desktops and servers.
- p1necone 7y ago
  globular-toast seems to be arguing past everyone because they're imagining a reality where a. these hypothetical ultra high clocked single core CPUs actually exist, and b. they have unlimited spending money and don't care at all about power usage or cooling.
7y ago