5 ms·

> they can't even come up with 1/3 of the speed of a 2016 Xeon Ultimately it's the total cost to run your application that's important, not the raw speed of a

> they can't even come up with 1/3 of the speed of a 2016 Xeon Ultimately it's the total cost to run your application that's important, not the raw speed of a particular core. So 1/3 speed is no problem if it's 1/4 the price (indeed this is the kind of trade-off you'd hope for in an ARM server). Sadly from the same tweet thread that quote came from: 'All in all: Amazon having Arm-based offering is a great first step, but it does not seem to be a particularly appealing one at the moment, (at least for me: especially since the cost difference is nonexistent if I was to match my existing performance.)'. So, for this particular application at least, the A1 instances aren't giving a good cost/performance ratio.

wmf 8y ago
Ultimately it's the total cost to run your application that's important, not the raw speed of a particular core. Not necessarily. A core that's 1/3 the speed can multiply your response time by 3x. https://static.googleusercontent.com/media/research.google.com/en//pubs/archive/36448.pdf https://static.googleusercontent.com/media/research.google.c...
- rbanffy 8y ago
  It depends on how CPU-bound you are. If you spend a lot of time waiting for DRAM, disk or network, then you won't notice. It's a bit like answering e-mail on a Celeron Chromebook compared to your dual Xeon Platinum quad Nvidia desktop. You won't notice the difference. 90% of the time the only difference I notice between my light-and-slow laptop I use for meetups and conferences and my heavy-and-beefy one is that the puny one has no built-in fan. When running Python code, my very methodologically questionable benchmarks indicate the size of the L1 cache makes a huge difference, so I'll take an ARM64 box with a Core i9 worth of transistors used as cache over the i9 with an ARM64 worth of cache any time.
  - reitzensteinm 8y ago
    Disk or network sure, but I don't think you can by any reasonable definition divorce "core performance" from the cache hierarchy and memory bandwidth that feeds it, at least in the context of the GP's post.
davrosthedalek 8y ago
It's important to note here that it's not the chip which has to be cheaper, but the whole setup. If a arm chip is 1/3 of the speed, I need three cpus, three mainboards, three switch ports, more ram (because I have to run three OS instances) etc.
- rbanffy 8y ago
  Only if you are CPU-bound (which is rarely the case).
  - davrosthedalek 8y ago
    No. If the system, for my task, is a factor 3 slower (in the sense it can handle 1/3 of the tasks in a given time), I need three of them. And as a parallel comment points out, this does not solve the issue of latency.
    - rbanffy 8y ago
      How much time does your CPU spend waiting for IO during your typical tasks?
      - davrosthedalek 8y ago
        Please read the whole thread. We are talking about a web server which is a factor of three slower. I really don't care why. The /package/ is factor 3 slower. Assuming that the rest of the system, i.e. mainboard etc., is at a similar cost level, it's not enough that the CPU is factor 3 cheaper. That was my point.
        ksec 8y ago
        And that is why I said it didn't make sense for ARM to be on Public Cloud, unless it is super cheap or you are on a very specific niche like Cloudflare and do low level optimisation while paying for your own electricity usage. CPU cost of a system percentage has dropped over the years when Memory prices are sky high. The only contender here is EPYC2.

wmf 8y ago

Ultimately it's the total cost to run your application that's important, not the raw speed of a particular core. Not necessarily. A core that's 1/3 the speed can multiply your response time by 3x. https://static.googleusercontent.com/media/research.google.com/en//pubs/archive/36448.pdf https://static.googleusercontent.com/media/research.google.c...

rbanffy 8y ago
It depends on how CPU-bound you are. If you spend a lot of time waiting for DRAM, disk or network, then you won't notice. It's a bit like answering e-mail on a Celeron Chromebook compared to your dual Xeon Platinum quad Nvidia desktop. You won't notice the difference. 90% of the time the only difference I notice between my light-and-slow laptop I use for meetups and conferences and my heavy-and-beefy one is that the puny one has no built-in fan. When running Python code, my very methodologically questionable benchmarks indicate the size of the L1 cache makes a huge difference, so I'll take an ARM64 box with a Core i9 worth of transistors used as cache over the i9 with an ARM64 worth of cache any time.
- reitzensteinm 8y ago
  Disk or network sure, but I don't think you can by any reasonable definition divorce "core performance" from the cache hierarchy and memory bandwidth that feeds it, at least in the context of the GP's post.

davrosthedalek 8y ago

It's important to note here that it's not the chip which has to be cheaper, but the whole setup. If a arm chip is 1/3 of the speed, I need three cpus, three mainboards, three switch ports, more ram (because I have to run three OS instances) etc.

rbanffy 8y ago
Only if you are CPU-bound (which is rarely the case).
- davrosthedalek 8y ago
  No. If the system, for my task, is a factor 3 slower (in the sense it can handle 1/3 of the tasks in a given time), I need three of them. And as a parallel comment points out, this does not solve the issue of latency.
  - rbanffy 8y ago
    How much time does your CPU spend waiting for IO during your typical tasks?
    - davrosthedalek 8y ago
      Please read the whole thread. We are talking about a web server which is a factor of three slower. I really don't care why. The /package/ is factor 3 slower. Assuming that the rest of the system, i.e. mainboard etc., is at a similar cost level, it's not enough that the CPU is factor 3 cheaper. That was my point.
      - ksec 8y ago
        And that is why I said it didn't make sense for ARM to be on Public Cloud, unless it is super cheap or you are on a very specific niche like Cloudflare and do low level optimisation while paying for your own electricity usage. CPU cost of a system percentage has dropped over the years when Memory prices are sky high. The only contender here is EPYC2.