crypto: passing configuration parameters to comp algos
Hi,
We'd like to be able to pass algorithm-specific parameters to
comp backends. As of this moment, crypto usees hard-coded default values and does not permit any run-time algorithm configuration, which in some cases simply disables the most interesting functionality. E.g. zstd can be configured to use a pre-trained (in the user-space) compression dictionary, which significantly changes algorithms characteristics. Another, obvious and trivial example, is algorithms compression level.
The problem is that we need to pass params to cra_init() function, because for some algorithms that's the only place where configuration can take place (e.g. zstd). Changing cra_init() to accept additional struct crypto_comp_params looks to be a little intrusive so before I write any patches I'd like to hear your thoughts.
Quoted 11 lines · Sergey Senozhatsky
Hi,
We'd like to be able to pass algorithm-specific parameters to
comp backends. As of this moment, crypto usees hard-coded default values and does not permit any run-time algorithm configuration, which in some cases simply disables the most interesting functionality. E.g. zstd can be configured to use a pre-trained (in the user-space) compression dictionary, which significantly changes algorithms characteristics. Another, obvious and trivial example, is algorithms compression level.
Quoted 6 lines
The problem is that we need to pass params to
cra_init()function, because for some algorithms that's the only place where configuration can take place (e.g. zstd). Changingcra_init()to accept additionalstruct crypto_comp_paramslooks to be a little intrusive so before I write any patches I'd like to hear your thoughts.
Have you considered just using the zstd library (<linux/zstd.h>) directly?
Which kernel subsystem are you working on that uses compression?
- Eric
Quoted 12 lines · Eric Biggers
Quoted 11 lines · Sergey Senozhatsky
Hi,
We'd like to be able to pass algorithm-specific parameters to
comp backends. As of this moment, crypto usees hard-coded default values and does not permit any run-time algorithm configuration, which in some cases simply disables the most interesting functionality. E.g. zstd can be configured to use a pre-trained (in the user-space) compression dictionary, which significantly changes algorithms characteristics. Another, obvious and trivial example, is algorithms compression level.
Quoted 8 lines
Quoted 6 lines
The problem is that we need to pass params to
cra_init()function, because for some algorithms that's the only place where configuration can take place (e.g. zstd). Changingcra_init()to accept additionalstruct crypto_comp_paramslooks to be a little intrusive so before I write any patches I'd like to hear your thoughts.Have you considered just using the zstd library (<
linux/zstd.h>) directly?
Yes, sort of.
Quoted 1 line
Which kernel subsystem are you working on that uses compression?
Forgot to mention - this is for zram primarily (and potentially for zswap). Both of which take advantage of crypto API and can be configured to use various compression algorithms (per-device).
So, on the zram side, in theory, I can stop using crypto API and start calling lzo/zstd/lz4/etc. compression/decompression functions directly (in fact we used to do that many many years ago, before we switched to cypto API).