6 ms·

How about single core performance? Many games are pegged to one or two cores only. I've always found the AMD approach of throwing more cores at the problem not

by bzb3 6y ago

How about single core performance? Many games are pegged to one or two cores only. I've always found the AMD approach of throwing more cores at the problem not to be optimal.

gambiting 6y ago
>> Many games are pegged to one or two cores only That hasn't been the case for a looong time. But to answer your question, they are much faster than anything from Intel at comparable pricing: https://www.eurogamer.net/articles/digitalfoundry-2020-amd-ryzen-3100-3300x-cpu-review https://www.eurogamer.net/articles/digitalfoundry-2020-amd-r... "The results here are immediately interesting. Despite costing less than every other CPU represented, the 3100 manages to tie the Core i5 9600K in single-core performance and outperform the Ryzen 2600 and 2700X by around 12 per cent. The 3300X is even more impressive, with a single-core score that exceeds the Core i7 9700K and only falls behind the Ryzen 9 3900X and Core i9 9900K."
- jdsully 6y ago
  I have a Ryzen 3900X, and also an i5 for software development. With unoptimized code the Ryzen is pretty close to the i5. But when you start to really optimize it becomes obvious the i5 has more execution resources and is faster single threaded.
  - ccffpphh 6y ago
    Is this including SPECTRE, etc. mitigations?
    - jeffbee 6y ago
      Why would anyone enable speculative execution mitigations on a computer used to build software?
      - monotypical 6y ago
        because it's the default on most operating systems
      - londons_explore 6y ago
        Building software with lots of opensource libraries is effectively giving shell access to the authors of those libraries. They can stick whatever they like in those build scripts, and there's so many thousands of them I bet you don't check all of them by hand. Given that, I'd prefer they had shell access as a low privilege user than be able to read my ssh keys from RAM... Obviously if you compile software as your regular linux user account like most users, you're already a sitting duck, so might as well throw in a few more vulnerabilities.
      - josteink 6y ago
        Because you’re downloading lots of untrustable source from npm and friends when you are fetching your dependencies.
    - jdsully 6y ago
      Yes default settings. The code we’re talking about is a hand rolled LZF decompressor originally written on the Ryzen 9 (so not intentionally Intel optimized). Spectre doesn’t make much difference since its not making syscalls. If you can somehow keep the CPU fed it becomes obvious there is more oomph behind the Intel device. That said how often are you running hand rolled assembly routines? As an additional datapoint liblzf is faster on the Ryzen. But its limited by pipeline stalls so doesn’t get to take advantage of the extra resources.
  - hansvm 6y ago
    I haven't looked at their newer offerings, but in years past that was definitely a problem that afflicted AMD -- having a fraction of the floating point execution units per core, creating AVX by adding an emulation layer over the existing SSE registers, etc. For a lot of use cases AMD could still be faster according to a wall clock (they weren't worse across the board -- those failings were used to purchase advantages in other chip features), but their peak flops were peanuts in comparison to the Intel offerings.
    - jdsully 6y ago
      That part is fixed. They even eliminated most of the downclocking issues with the AVX units on Intel. AMD has been pretty tactical with Zen2. The issues I’m talking about are execution resources for scalar code. Things like how many ALUs and which execution ports are able to execute which instructions.
  - pornel 6y ago
    When you optimize for maximum performance, leaving 11 cores idle is very sad.
    - jdsully 6y ago
      If your algorithm is already parallel then you go back to making each core do more work per cycle.
  - deleted 6y ago
    [deleted]
  - zrm 6y ago
    Most benchmarks show the 3900X with single thread performance competitive with Intel's offerings, including for software whose developers spend plenty of time optimizing it. Can you think of a reason they haven't realized this performance advantage in practice?
    - jdsully 6y ago
      Zen is great if you have moderate utilization code around the ~2-3 instructions per cycle mark. This is common for most compiled C and C++ where it hasn’t been specifically tuned for ILP. In these scenarios even if Intel has an extra ALU it won’t be used anyways. It took 3 days of tuning to get to a point where Intel started pulling away from my Zen2 chip. No matter what I did the Zen2 would not get faster because it was already at max utilization. Lemire had a blog [1] talking about this on here a few months ago as well. Most people were surprised because frankly Zen2 is very competitive with Intel for normal compiled code. https://lemire.me/blog/2019/12/05/instructions-per-cycle-amd-versus-intel/ https://lemire.me/blog/2019/12/05/instructions-per-cycle-amd...
      - zrm 6y ago
        Are you measuring actual performance though or just IPC? We know Intel has that problem with AVX-512. You can get a lot of throughput per cycle with those instructions but the cost is they cause the processor to run hot and have to downclock. It's possible (and really expected) that the same thing happens to some extent at unusually high IPC. Getting 15% higher IPC doesn't really buy you anything if the processor has to lower its clock speed by 15% to execute that type of code.
        jdsully 6y ago
        Actual wallclock time. The code is 100% scalar - LZF is very byte oriented and I haven't found a good way to vectorize it. IPC counts were used to help guide tuning but not a determination of success. I don't really understand why people think this is controversial. Somehow an Intel cpu on a generation behind process is still competitive with a 7nm CPU with more cache. Intel must have one hell of an architecture to make that possible. AMD did a good job for the most common workloads but they have work to do with Zen3 if they want to maintain that lead when Intel finally figures out its manufacturing.
sjwright 6y ago
It’s worth remembering that the PS4 and XB1 consoles both have eight relatively slow x64 cores. Thus any multiplatform titles targeting either of these platforms has to be optimised for many cores and cannot rely on single core performance.
- bzb3 6y ago
  Definitely. But in my case I don't play the last of the last. Most games I play such as world of Warcraft or csgo use old engines and don't take advantage of many cores.
  - hyperbovine 6y ago
    But that was not your original premise. "Many" games are not single core. Rather, a few old classics that refuse to die are.
    - bzb3 6y ago
      https://store.steampowered.com/stats/Steam-Game-and-Player-Statistics https://store.steampowered.com/stats/Steam-Game-and-Player-S... Probably most games on that list don't use all cores. So yeah not "many" but "most". Thanks for the correction.
      - taway555 6y ago
        Please provide sources for core usage for each of the games referenced in your list.
      - sjwright 6y ago
        Any older single core game will run just fine on probably any (non-embedded) x64 CPU on sale right now. Your original premise simply isn’t a problem.
        paulmd 6y ago
        You might be surprised, "older single-core games" like Crysis and Skyrim really do not run all that well even with "modern" architectures behind them. And in particular they often do quite poorly with AMD due to latency issues. Per-thread performance really hasn't improved all that much since the days of, say, a 4.7 GHz 2600K. Core counts have gone up drastically, but that doesn't help your single-threaded game from 2007.
jeffbee 6y ago
It's really hard to glean from the article, which is I guess just designed to get 500+ ad impressions by spreading the information over 33 pages. This comparison of the same data is a little more informative: https://www.anandtech.com/bench/product/2589?vs=2250 https://www.anandtech.com/bench/product/2589?vs=2250 That's a $199 Intel 6-core part against a $120 AMD 4-core part. Anandtech hasn't bothered to benchmark a 4-core 9th-generation Intel CPU yet, despite the fact that they hit retail a year ago.
- IanCutress 6y ago
  'Hasn't bothered' = not been sampled.
  - jeffbee 6y ago
    AnandTech only reviews parts that manufacturers send them for free? Isn't that the opposite of an ethical policy (e.g. the one followed by Consumer Reports?) As it says on "About AnandTech", "one way or another we'll get our hands on a product for review".

by bzb3 6y ago

How about single core performance? Many games are pegged to one or two cores only. I've always found the AMD approach of throwing more cores at the problem not to be optimal.

gambiting 6y ago

>> Many games are pegged to one or two cores only That hasn't been the case for a looong time. But to answer your question, they are much faster than anything from Intel at comparable pricing: https://www.eurogamer.net/articles/digitalfoundry-2020-amd-ryzen-3100-3300x-cpu-review https://www.eurogamer.net/articles/digitalfoundry-2020-amd-r... "The results here are immediately interesting. Despite costing less than every other CPU represented, the 3100 manages to tie the Core i5 9600K in single-core performance and outperform the Ryzen 2600 and 2700X by around 12 per cent. The 3300X is even more impressive, with a single-core score that exceeds the Core i7 9700K and only falls behind the Ryzen 9 3900X and Core i9 9900K."

jdsully 6y ago
I have a Ryzen 3900X, and also an i5 for software development. With unoptimized code the Ryzen is pretty close to the i5. But when you start to really optimize it becomes obvious the i5 has more execution resources and is faster single threaded.
- ccffpphh 6y ago
  Is this including SPECTRE, etc. mitigations?
  - jeffbee 6y ago
    Why would anyone enable speculative execution mitigations on a computer used to build software?
    - monotypical 6y ago
      because it's the default on most operating systems
    - londons_explore 6y ago
      Building software with lots of opensource libraries is effectively giving shell access to the authors of those libraries. They can stick whatever they like in those build scripts, and there's so many thousands of them I bet you don't check all of them by hand. Given that, I'd prefer they had shell access as a low privilege user than be able to read my ssh keys from RAM... Obviously if you compile software as your regular linux user account like most users, you're already a sitting duck, so might as well throw in a few more vulnerabilities.
    - josteink 6y ago
      Because you’re downloading lots of untrustable source from npm and friends when you are fetching your dependencies.
  - jdsully 6y ago
    Yes default settings. The code we’re talking about is a hand rolled LZF decompressor originally written on the Ryzen 9 (so not intentionally Intel optimized). Spectre doesn’t make much difference since its not making syscalls. If you can somehow keep the CPU fed it becomes obvious there is more oomph behind the Intel device. That said how often are you running hand rolled assembly routines? As an additional datapoint liblzf is faster on the Ryzen. But its limited by pipeline stalls so doesn’t get to take advantage of the extra resources.
- hansvm 6y ago
  I haven't looked at their newer offerings, but in years past that was definitely a problem that afflicted AMD -- having a fraction of the floating point execution units per core, creating AVX by adding an emulation layer over the existing SSE registers, etc. For a lot of use cases AMD could still be faster according to a wall clock (they weren't worse across the board -- those failings were used to purchase advantages in other chip features), but their peak flops were peanuts in comparison to the Intel offerings.
  - jdsully 6y ago
    That part is fixed. They even eliminated most of the downclocking issues with the AVX units on Intel. AMD has been pretty tactical with Zen2. The issues I’m talking about are execution resources for scalar code. Things like how many ALUs and which execution ports are able to execute which instructions.
- pornel 6y ago
  When you optimize for maximum performance, leaving 11 cores idle is very sad.
  - jdsully 6y ago
    If your algorithm is already parallel then you go back to making each core do more work per cycle.
- deleted 6y ago
  [deleted]
- zrm 6y ago
  Most benchmarks show the 3900X with single thread performance competitive with Intel's offerings, including for software whose developers spend plenty of time optimizing it. Can you think of a reason they haven't realized this performance advantage in practice?
  - jdsully 6y ago
    Zen is great if you have moderate utilization code around the ~2-3 instructions per cycle mark. This is common for most compiled C and C++ where it hasn’t been specifically tuned for ILP. In these scenarios even if Intel has an extra ALU it won’t be used anyways. It took 3 days of tuning to get to a point where Intel started pulling away from my Zen2 chip. No matter what I did the Zen2 would not get faster because it was already at max utilization. Lemire had a blog [1] talking about this on here a few months ago as well. Most people were surprised because frankly Zen2 is very competitive with Intel for normal compiled code. https://lemire.me/blog/2019/12/05/instructions-per-cycle-amd-versus-intel/ https://lemire.me/blog/2019/12/05/instructions-per-cycle-amd...
    - zrm 6y ago
      Are you measuring actual performance though or just IPC? We know Intel has that problem with AVX-512. You can get a lot of throughput per cycle with those instructions but the cost is they cause the processor to run hot and have to downclock. It's possible (and really expected) that the same thing happens to some extent at unusually high IPC. Getting 15% higher IPC doesn't really buy you anything if the processor has to lower its clock speed by 15% to execute that type of code.
      - jdsully 6y ago
        Actual wallclock time. The code is 100% scalar - LZF is very byte oriented and I haven't found a good way to vectorize it. IPC counts were used to help guide tuning but not a determination of success. I don't really understand why people think this is controversial. Somehow an Intel cpu on a generation behind process is still competitive with a 7nm CPU with more cache. Intel must have one hell of an architecture to make that possible. AMD did a good job for the most common workloads but they have work to do with Zen3 if they want to maintain that lead when Intel finally figures out its manufacturing.

sjwright 6y ago

It’s worth remembering that the PS4 and XB1 consoles both have eight relatively slow x64 cores. Thus any multiplatform titles targeting either of these platforms has to be optimised for many cores and cannot rely on single core performance.

bzb3 6y ago
Definitely. But in my case I don't play the last of the last. Most games I play such as world of Warcraft or csgo use old engines and don't take advantage of many cores.
- hyperbovine 6y ago
  But that was not your original premise. "Many" games are not single core. Rather, a few old classics that refuse to die are.
  - bzb3 6y ago
    https://store.steampowered.com/stats/Steam-Game-and-Player-Statistics https://store.steampowered.com/stats/Steam-Game-and-Player-S... Probably most games on that list don't use all cores. So yeah not "many" but "most". Thanks for the correction.
    - taway555 6y ago
      Please provide sources for core usage for each of the games referenced in your list.
    - sjwright 6y ago
      Any older single core game will run just fine on probably any (non-embedded) x64 CPU on sale right now. Your original premise simply isn’t a problem.
      - paulmd 6y ago
        You might be surprised, "older single-core games" like Crysis and Skyrim really do not run all that well even with "modern" architectures behind them. And in particular they often do quite poorly with AMD due to latency issues. Per-thread performance really hasn't improved all that much since the days of, say, a 4.7 GHz 2600K. Core counts have gone up drastically, but that doesn't help your single-threaded game from 2007.

jeffbee 6y ago

It's really hard to glean from the article, which is I guess just designed to get 500+ ad impressions by spreading the information over 33 pages. This comparison of the same data is a little more informative: https://www.anandtech.com/bench/product/2589?vs=2250 https://www.anandtech.com/bench/product/2589?vs=2250 That's a $199 Intel 6-core part against a $120 AMD 4-core part. Anandtech hasn't bothered to benchmark a 4-core 9th-generation Intel CPU yet, despite the fact that they hit retail a year ago.

IanCutress 6y ago
'Hasn't bothered' = not been sampled.
- jeffbee 6y ago
  AnandTech only reviews parts that manufacturers send them for free? Isn't that the opposite of an ethical policy (e.g. the one followed by Consumer Reports?) As it says on "About AnandTech", "one way or another we'll get our hands on a product for review".