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How much memory bandwidth do large Amazon instances offer?

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Re: How much memory bandwidth do large Amazon instances offer?

#21

Post by shivam543 »

andrewgross wrote: post #19

7950x3d w/ 128GB at stock timings (~3200MT/s?). Showed a high base but no increase with threads, need to investigate what is happening. 1 54.7 2 50.6 3 49.6 4 48.2 5 47.9 6 47.4 7 47.1 8 46.6 9 46.5 10 46.2 11 46.1 12 45.9 13 45.8 14 45.7 15 45.7 16 45.7 17 45.7 18 45.8 19 45.9 20 45.8 21 45.8 22 45.6 23 45.6 24 45.5 25 45.5 26 45.5 27 45.5 28 45.4 29 45.4 30 45.4 31 45.4 32 45.4

For 2 x 3200 MHz, 51.2 GB/s is the theoretical limit. I guess your single core is good enough to use all bandwidth. How many RAM sticks do you have?

Re: How much memory bandwidth do large Amazon instances offer?

#22

Post by andrewgross »

shivam543 wrote: post #21
andrewgross wrote: post #19

7950x3d w/ 128GB at stock timings (~3200MT/s?). Showed a high base but no increase with threads, need to investigate what is happening. 1 54.7 2 50.6 3 49.6 4 48.2 5 47.9 6 47.4 7 47.1 8 46.6 9 46.5 10 46.2 11 46.1 12 45.9 13 45.8 14 45.7 15 45.7 16 45.7 17 45.7 18 45.8 19 45.9 20 45.8 21 45.8 22 45.6 23 45.6 24 45.5 25 45.5 26 45.5 27 45.5 28 45.4 29 45.4 30 45.4 31 45.4 32 45.4

For 2 x 3200 MHz, 51.2 GB/s is the theoretical limit. I guess your single core is good enough to use all bandwidth. How many RAM sticks do you have?

4 x 32GB for now. I need to investigate manual OC as EXPO doesn't work with all 4 slots populated. Another option is to try the 192GB 4x48GB Corsair kits at 5200.

Re: How much memory bandwidth do large Amazon instances offer?

#24

Post by jmole »

M1 Pro Macbook 32GB:

    1 51.1
    2 99.4
    3 108.2
    4 121.3
    5 116.4
    6 122.9
    7 122.0
    8 123.2
    9 125.6
    10 124.9
Xeon E-2288G (aka i9-9900K) 128GB DDR4-2666:

    $ ./a.out
    1 19.7
    2 27.8
    3 30.0
    4 31.7
    5 33.6
    6 34.4
    7 33.9
    8 33.2
    9 32.2
    10 32.2
    11 32.3
    12 32.1
    13 31.9
    14 31.5
    15 31.2
    16 30.9

Re: How much memory bandwidth do large Amazon instances offer?

#25

Post by skywhopper »

Interesting stuff, although I'll admit when I read the headline I took it to mean the literal `large` instance types, which are actually quite small as AWS lingo goes. Whereas the author means actual LARGE instances, ie, an entire box with no hypervisor layer.

Re: How much memory bandwidth do large Amazon instances offer?

#26

Post by gavinray »

Note that you can get a significant speedup by using "restrict" on the pointer in the "sum()" function to tell the compiler that there is no mutation or aliasing happening during the call's lifetime.

On Godbolt, with a size of 100MB (due to limits), this improves the speed using LLVM 17 (https://godbolt.org/z/6dW1h8aev) from:

  1 15.1 
  2 15.9
To (https://godbolt.org/z/sh3489Mxv)

  1 12.8 
  2 13.7

Re: How much memory bandwidth do large Amazon instances offer?

#28

Post by seiferteric »

andrewgross wrote: post #19

7950x3d w/ 128GB at stock timings (~3200MT/s?). Showed a high base but no increase with threads, need to investigate what is happening. 1 54.7 2 50.6 3 49.6 4 48.2 5 47.9 6 47.4 7 47.1 8 46.6 9 46.5 10 46.2 11 46.1 12 45.9 13 45.8 14 45.7 15 45.7 16 45.7 17 45.7 18 45.8 19 45.9 20 45.8 21 45.8 22 45.6 23 45.6 24 45.5 25 45.5 26 45.5 27 45.5 28 45.4 29 45.4 30 45.4 31 45.4 32 45.4

7950x with 32GB @ 6000MT/s:

    1 52.6
    2 78.1
    3 71.0
    4 74.3
    5 71.3
    6 72.5
    7 70.0
    8 69.6
    9 68.4
    10 68.7
    11 68.5
    12 68.3
    13 68.3
    14 68.0
    15 67.8

Re: How much memory bandwidth do large Amazon instances offer?

#29

Post by speedgoose »

Running on an 2xARM Cavium ThunderX2 CN9980 with 1TB of ram and 256 threads (Simula Ex3): ~120.

Running on an 2xAMD EPYC 7763 64-Core Processor, with 256GB of ram and 256 threads (EuroHPC LUMI standard CPU node): ~38.

Running on my Macbook Pro M1 16GB on battery power, but with 8GB of data to not swap as I have other apps running: ~59.

Re: How much memory bandwidth do large Amazon instances offer?

#30

Post by dd_xplore »

I changed data_volume to 8GB and ran on my desktop (Amd Ryzen5 7600X + 2x8GB DDR5-4800 running @ 5000 Mhz)(Win11) I get around 55 GB/s

  PS E:\> .\bandwidth.exe  
  1 54.0  
  2 56.7  
  3 56.1  
  4 55.3  
  5 54.6  
  6 54.3  
  7 53.9  
  8 53.1  
  9 53.4  
  10 53.1  
  11 52.3  
  12 52.8
55 is kinda low for DDR5 I guess..

On S23 Ultra (Snapdragon 8 Gen 2+, 12GB LPDDR5X @4200MHz)

  u0_a339@localhost ~> ./bandwidth
  1 34.4 GB/s
  2 38.7 GB/s
  3 42.0 GB/s
  4 42.3 GB/s
  5 42.4 GB/s
  6 40.2 GB/s
  7 41.0 GB/s
  8 40.3 GB/s
On a NanoPi-R6C (RockChip RK3588s @2.4Ghz + 8GB LPDDR4X)

  pi@nanopi ~> ./bandwidth
  1 22.1 GB/s
  2 26.2 GB/s
  3 27.5 GB/s
  4 27.7 GB/s
  5 27.1 GB/s
  6 27.1 GB/s
  7 27.0 GB/s
  8 26.9 GB/s
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