New C5a benchmark: Performance/Price

AWS recently released the new series C5a equipped with custom AMD EPYC 7R32. We can discover here, a less expensive alternative to C5, similar to what they did with M5, R5 and T3. But cost isn’t an appropriated metric if you doesn’t take in account performance, so let’s dive into a performance/price benchmark comparing C5 and C5a.

A lower pricing

Name CPU RAM C5 C5a
large 2 4 0.085 0.077
xlarge 4 8 0.170 0.154
2xlarge 8 16 0.340 0.308
4xlarge 16 32 0.680 0.616
9xlarge 36 72 1.530 1.232
12xlarge 48 96 2.040 1.848
18xlarge 72 144 3.060 2.464
24xlarge 96 192 4.080 3.696
metal 96 192 4.080

Pricing is for East US (Ohio)

Performance a bit better

Before open the hood, there are 2 things to keep in mind about C5: CPU performance is highly variable. Behind the product names, several CPU model are sold and we actually collected the following:

  • Intel(R) Xeon(R) Platinum 8124M
  • Intel(R) Xeon(R) Platinum 8275CL

Like the new AMD EPYC 7R32, both are custom models only available at AWS. Next thing, a same CPU model works at different frequencies. Generally, Cloud Providers set their CPU frequency at baseline or turbo frequency, for Platinum 8124M, we detected values from 3 up to 3.45GHz.

Geekbench 5

Kind c5.large c5a.large
Single score 934 909
Single Integer 902 815
Single Float 949 969
Single Crypto 1267 1782
Multi score 1115 1168
Multi Integer 1049 1067
Multi Float 1200 1256
Multi Crypto 1470 1952

From a Geekbench perspective, C5a excels especially in cryptography realm which is not a subject to underestimate, nowadays encryption is something used everywhere, from volumes to HTTP connections or with any backend. Other domain are also more efficient but not with a huge gap.

sysbench RAM

c5.large c5a.large
Read 8201 9139
Write 6134 7091

RAM bandwidth is a good indicator of neighborough’s noise and as C5a has just been released its value has higher chance to be better. Then, we’ll also check regularly if C5 and C5a can still pretend the same throughput.

Performance/Price

Viewing the results below and knowing instances’ prices are 10% lower, it’s not a surprise that C5a has better profile in terms of performance per dollar spent.

Type Hourly Monthly Multi score Perf/price ratio
c5.large 0.085 62.05 1115 17.97
c5a.large 0.077 56.21 1168 18.82

Monthly price is calculated from 730 hours.
Perf/price ratio equals “Mult-score / Monthly”

Conclusion

With this new original CPU model, AWS decreases their pricing again but with some performance increasement. In the past with the previous C5, we observed a lot of performance variation and it wouldn’t be a surprise if future tests pull the average performance up or down.

As the full series cannot be described by its smaller instance type, we also tested bigger flavors. Feel free to consult their performance on our Public Cloud Reference.

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