4 ms·

They are decent, but don't seem quite as good as the ones on AMD's (or even more Intel's) processors. Qualcomm Centriq 2434 [https://www.nextplatform.com/2017/

by devit 9y ago

They are decent, but don't seem quite as good as the ones on AMD's (or even more Intel's) processors. Qualcomm Centriq 2434 [https://www.nextplatform.com/2017/11/08/qualcomms-amberwing-arm-server-chip-finally-takes-flight/ https://www.nextplatform.com/2017/11/08/qualcomms-amberwing-...]: - 40 cores (no SMT) - 2.5 GHz peak - 4 uops/instructions per cycle [https://www.qualcomm.com/media/documents/files/qualcomm-centriq-2400-processor.pdf https://www.qualcomm.com/media/documents/files/qualcomm-cent...] - 110 W TDP - $888 - 10 Guops/s/core - 0.011 Guops/s/core/$ - 400 Guops/s - 0.45 Guops/s/$ - 3.63 Guops/s/W AMD Epyc 7401P [https://en.wikipedia.org/wiki/Epyc https://en.wikipedia.org/wiki/Epyc]: - 24 cores (2x SMT) - 2.8 GHz all-core boost - 6 uops per cycle [http://www.agner.org/optimize/microarchitecture.pdf http://www.agner.org/optimize/microarchitecture.pdf] - 170 W TDP - $1075 - 16.8 Guops/s/core - 0.016 Guops/s/core/$ - 403 Guops/s - 0.37 Guops/s/$ - 2.37 Guops/s/W So based on this the AMD processor has 170% the Qualcomm's per-core performance, equal on total throughput, 83% of Qualcomm's total thoughput per $ and 65% of Qualcomm's total throughput per W. Note that the AMD CPU has SMT while the Qualcomm doesn't which improves utilization, and its components are probably faster (due to higher TDP and more experience making CPUs), so it looks like the AMD CPUs are likely to be strictly better in practice except possibly on performance/watt. Also, with AMD/Intel, albeit at much lower performance/$, you can have 32-core instead of 24-core CPUs and there is up to 4/8-way SMP support that Qualcomm doesn't mention.

kogepathic 9y ago
> so it looks like the AMD CPUs are likely to be strictly better in practice except possibly on performance/watt. Cloud scale providers don't care about raw performance (within reason). TCO wins the day, so if Qualcomm CPUs offer higher performance per watt than Intel or AMD, I can definitely see them buying these like hotcakes.
bhouston 9y ago
They do seem surprisingly decent. Not yet clearly better, but they are surprisingly decent. It is too bad someone has't made a graph of these two trajectories, Intel/AMD performance and ARM performance, over time. I bet it would let us see if there is going to be an intercept between the two and when it would happen. We have like 7 years of data now in this race, a graph should be possible.
gok 9y ago
Hold up. Comparing uops/sec between CPU architectures is not meaningful.
- jabl 9y ago
  Yes. Furthermore, the assumption that a core being capable of a maximum of x uops/cycle means that the core actually executes x uops/cycle when running a workload seems really far-fetched.
thecompilr 9y ago
This is the most meaningless comparison you could possibly make. By this logic Pentium 4 is also better, because it had 3.8 peak GHz, SMT and could do 4 uops/cycle. In reality things don't work like that. First of all some of the uops can only be loads, others stores and other branches. Second, you have factors like branch prediction, cache latency, branch mis-prediction penalty that plays a huge role on performance. I am yet to see a workload that can saturate 6 execution ports, even with SMT. In the real world Centriq is better in performance/watt, and is even better in perfomance/thread that an SMT thread on an Intel Skylake.
- Joky 9y ago
  > In the real world Centriq is better in performance/watt, and is even better in perfomance/thread that an SMT thread on an Intel Skylake. Is there one such thing as "in the real world"? I mean isn't it use-case dependent and if you want a build machine, a web server, or a database server you'll get different results out of your benchmarks?
  - thecompilr 9y ago
    I am sorry, you are 100% correct. There are workloads where you can't beat Intel. Pure number crunching for example, where you can utilize AVX-512. I meant in the real world of (most) web servers in this case.
    - geezerjay 9y ago
      > There are workloads where you can't beat Intel. Pure number crunching for example, where you can utilize AVX-512. That's also debatable. I've read HPC papers that show opterons outperforming xeons on heavy fp workloads due to the higher throughput and larger cache. Baseless claims regarding "real world performance" are only good for marketeers.
      - rbanffy 9y ago
        Edge cases are edge cases. I once made a semi-retired 5 year-old server crush a brand new one on a specific workload just because I noticed the working dataset did fit entirely in its L2 cache. Will I ever do it again? I have no idea. At the time, I got a very nice bottle of wine for my bet.

by devit 9y ago

kogepathic 9y ago

> so it looks like the AMD CPUs are likely to be strictly better in practice except possibly on performance/watt. Cloud scale providers don't care about raw performance (within reason). TCO wins the day, so if Qualcomm CPUs offer higher performance per watt than Intel or AMD, I can definitely see them buying these like hotcakes.

bhouston 9y ago

They do seem surprisingly decent. Not yet clearly better, but they are surprisingly decent. It is too bad someone has't made a graph of these two trajectories, Intel/AMD performance and ARM performance, over time. I bet it would let us see if there is going to be an intercept between the two and when it would happen. We have like 7 years of data now in this race, a graph should be possible.

gok 9y ago

Hold up. Comparing uops/sec between CPU architectures is not meaningful.

jabl 9y ago
Yes. Furthermore, the assumption that a core being capable of a maximum of x uops/cycle means that the core actually executes x uops/cycle when running a workload seems really far-fetched.

thecompilr 9y ago

This is the most meaningless comparison you could possibly make. By this logic Pentium 4 is also better, because it had 3.8 peak GHz, SMT and could do 4 uops/cycle. In reality things don't work like that. First of all some of the uops can only be loads, others stores and other branches. Second, you have factors like branch prediction, cache latency, branch mis-prediction penalty that plays a huge role on performance. I am yet to see a workload that can saturate 6 execution ports, even with SMT. In the real world Centriq is better in performance/watt, and is even better in perfomance/thread that an SMT thread on an Intel Skylake.

Joky 9y ago
> In the real world Centriq is better in performance/watt, and is even better in perfomance/thread that an SMT thread on an Intel Skylake. Is there one such thing as "in the real world"? I mean isn't it use-case dependent and if you want a build machine, a web server, or a database server you'll get different results out of your benchmarks?
- thecompilr 9y ago
  I am sorry, you are 100% correct. There are workloads where you can't beat Intel. Pure number crunching for example, where you can utilize AVX-512. I meant in the real world of (most) web servers in this case.
  - geezerjay 9y ago
    > There are workloads where you can't beat Intel. Pure number crunching for example, where you can utilize AVX-512. That's also debatable. I've read HPC papers that show opterons outperforming xeons on heavy fp workloads due to the higher throughput and larger cache. Baseless claims regarding "real world performance" are only good for marketeers.
    - rbanffy 9y ago
      Edge cases are edge cases. I once made a semi-retired 5 year-old server crush a brand new one on a specific workload just because I noticed the working dataset did fit entirely in its L2 cache. Will I ever do it again? I have no idea. At the time, I got a very nice bottle of wine for my bet.