Re: [PATCH v1 1/1] dm-integrity: Implement asynch digest support

Harald Freudenberger
2025-01-17T13:31:37Z

On 2025-01-15 18:29, Mikulas Patocka wrote:
> Hi
>
> The ahash interface is slower than the shash interface for synchronous
> implementations, so the patch is basically slowing down the common
> case.
> See the upstream commit b76ad8844234bd0d394105d7d784cd05f1bf269a for an
> explanation in dm-verity.
>
> Do you have some benchmark that shows how much does it help on s390x?
> So,
> that we can evaluate whether the added complexity is worth the
> performance
> improvement or not.
>
> Mikulas
>

Just a short sniff test on my development system (s390x with 32GB RAM,
16 CPUs).
When I run a dm-integrity format command on a 16G loopback file backed
up by tempfs
I get this on a fedora40 with fresh build v6.13-rc7 kernel:

integritysetup format /dev/loop0 --integrity sha256 --sector-size 4096
...
Finished, time 00m08s, 15 GiB written, speed 1.8 GiB/s

and with the same kernel + my dm-integrity async patch:

Finished, time 00m09s, 15 GiB written, speed 1.7 GiB/s

However, I'll run some more sophisticated performance measurements
during
the weekend.

Harald Freudenberger