Comment by dijit | Hacker News Reader

Comment by dijit | Hacker News Reader

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I don't buy it.

I'm actually a large fan of the Pi but people seem to think it's lower power than it actually is: but the performance trade-off is real.

the -peak- power consumption of a Pi is 15W (but it's difficult finding an adapter which will supply that).

So if we're talking peak power consumption the Pi would win because most decent quality mobile x86 chips draw something like 15w by themselves at peak, but if you look at something with the m3-8100y[0] then you've got a CPU that draws 5w at peak, and has 10 PCIe lanes instead of just 1.

they have boards with this kind of platform: https://www.dfrobot.com/product-1404.html

If you're looking to get a super low energy homeserver these absolutely dominate on peak usage.

But, a rpi and a laptop are roughly comparable in terms of idle power consumption. Unless it's like a gaming laptop or something. Mine draws 3w during "idle"* from the wall and I have a Xeon E3-1505M v6 (45W TDP).

[0]: https://ark.intel.com/content/www/us/en/ark/products/185282/...

- "idle" meaning with a few containers, a window manager, the screen turned on and wifi enabled/connected.

> I don't buy it.

Size? I’d never change my chinese x86, 10W TDP, mini-pc running OPNsense for a Pi. Its perfect size. But I have to use Pi for my drone video, nothing else will fit.

Sounds like a good excuse for a bigger drone.

its 650mm already :)

That’s fair. I’d also argue that the form factor has a good community around it.

I’m not saying there are no reasons. But people salivating at the Pis as a be all and end all of low energy devices are a bit annoying.

The Pi is primarily a tool for students and to a lesser extent: makers to get a general purpose computer to be as cheap as possible for the purpose of education.

But people want it to be home servers or to compete with other products of a higher price point. But it betrays the original purpose.

You need to compare apples to apples, CPU Gflops/W is the number for that.

And humanity is probably stuck between 2-3 for eternity (usable cheap X86/ARM/RISC-V, not fringe prototypes).

Pi 4 uses 7W CPU full 400% blast for about 14 Gflops, how much does the LattePanda give at peak?

Next step up is Atom at 25W.

Also you have to add size of the cluster and cost of the PSU and cables to the equation.

More PCI lanes is only interesting if you plan on using them.

File servers (or most server apps generally) don't do much FP. And gflops counts tend to incorporate SIMD lanes to get many times bigger numbers than scalar code, which again is not used by most server apps.

Ok, so what is the better metric?

I'm pretty sure Gflops on f.ex. this site is without SIMD as it makes no sense to compare CPUs like that: http://web.eece.maine.edu/~vweaver/group/green_machines.html

Not sure what's the best proxy benchmark, sorry. Maybe something like SPEC jbb or sfs benchmarks?

Re the numbers at that site, that's using OpenBLAS linpack which is likely utilizing SIMD but can also be memory bandwidth bound.

Ok, thanks for letting me know, I thought the world was sane and had a way to compare CPUs in an apples to apples fashion...

> More PCI lanes is only interesting if you plan on using them

I’m hard pressed to think what else you would want in a file server.

Storage uses PCI lanes (4 for NVMe), network uses PCI lanes (1 for each gigabit of network, typically).

I'm still stuck on SATA, don't see the point of NVMe because there is no application I want to write that needs that disk speed.

I use my servers as MMO backends, partly they will serve files, but mostly they'll do real-time networking and db stuff... some AI for the monsters and validation for anti-cheat so I need CPU more than fast storage or network.

Ok.

But, we’re talking home servers and for _most_ people that’s a file server, or something heavy with I/O and SATA is still I/O.

Most (if not all) SATA controllers interface to the CPU with PCIe (lspci will show you a SATA controller on the PCI bus)

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