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

[Harald Freudenberger <freude@linux.ibm.com>]

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