On (24/04/29 20:18), Eric Biggers wrote: > On Tue, Apr 30, 2024 at 12:04:47PM +0900, Sergey Senozhatsky wrote: > > 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. > > > > Have you considered just using the zstd library (<linux/zstd.h>) directly? Yes, sort of. > 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).
