[Linuxppc-users] [EXTERNAL] AES NX Coprocessor dm-crypt support

[Anton Blanchard]

Hi,

> I am interested in support for the NX AES Coprocessor as described in 
> section 11.1 and 25.3 of the POWER9 User Manual in Linux's dm-crypt.
> 
> Currently I am using LUKS on NVMe drives that advertise having
> 3.2GB/s read speeds (Samsung) and I am currently capped to 1GB/s with
> current on-chip instructions (vcipher etc).
> 
> If we consider the advertised performance for the NX Coprocessors and
> my dual CPU system, two NX engines per CPU (6.4 * 2 * 2), it would
> total for 25.6 Gbps 256bit AES performance which equals 3.2GB/s. That
> would allow me to use LUKS over my NVMe drives without performance
> loss, which is needless to say, quite awesome.

What algorithm are you using? Is it AES-XTS? On my box:

# cryptsetup benchmark --cipher aes-xts-plain64

#     Algorithm | Key |  Encryption |  Decryption
        aes-xts   256b  2332.2 MiB/s  2366.8 MiB/s

That's just crypto performance - adding in I/O will see that number drop,
but 1 GB/sec seems a bit low. I just took a look at the AES-XTS
algorithm and I see a few places we can pick up a bit of performance
(perhaps 10%).

Keep in mind that you are comparing a single threaded in core result
with a projected multi threaded NX result. The in core results will
scale with the number of cores you have, and even 2 cores will exceed
the performance of all 4 NX accelerators.

Thanks,
Anton

> 
> Another significant benefit of this would be XMR mining, the current 
> latest POWER miner does not make use of NX coprocessors. ( 
> https://urldefense.proofpoint.com/v2/url?u=https-3A__github.com_madscientist159_xmrig&d=DwICAg&c=jf_iaSHvJObTbx-siA1ZOg&r=azkGdnz7EYeVmhCvUFAXMMwzYZqpcBIElGi1DsA0tKU&m=Nito0Ak3Mdo6mT2SflTzQb-SP6s6Zzu4kvBvoWYcJek&s=1G2rfMAGH6r7CmZqKQaZy9InJT-f8AD2yKJPYMTuCF8&e= ).
> 
> How would I go about this? Currently there's a gzip implementation at 
> https://urldefense.proofpoint.com/v2/url?u=https-3A__github.com_abalib_power-2Dgzip&d=DwICAg&c=jf_iaSHvJObTbx-siA1ZOg&r=azkGdnz7EYeVmhCvUFAXMMwzYZqpcBIElGi1DsA0tKU&m=Nito0Ak3Mdo6mT2SflTzQb-SP6s6Zzu4kvBvoWYcJek&s=yCOEOyXyZMDPplivKtIC-X6iUbm2OcGxeqtt8qn07ac&e=
> - it's cited in the manual.
> 
> PS: I'm part of an active community around POWER9 and the Talos II 
> systems at #talos-workstation on Freenode IRC, feel free to join and 
> ping JSharp, tpearson, koenigni, awordnot or (myself) dftxbs3e about 
> this.
> 
> Thanks
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