On (24/05/10 15:40), Herbert Xu wrote: > > But in general case, a typical crypto API usage > > > > tfm = crypto_alloc_comp(comp->name, 0, 0); > > > > should become much more complex. I'd say that, probably, developing > > an entirely new sub-set of API would be simpler. > > We could easily add a setparams interface for acomp to support > this. The form of parameters would be specific to each individual > algorithm (but obviously all drivers for the same algorithm must > use the same format). For some algorithms params needs to be set before ctx is created. For example zstd, crypto/zstd calls zstd_get_params(ZSTD_DEF_LEVEL, 0) to estimate workspace size, which misses the opportunity to configure it an way zram/zswap can benefit from, because those work with PAGE_SIZE source buffer. So for zram zstd_get_params(ZSTD_DEF_LEVEL, PAGE_SIZE) is much better (it saves 1.2MB per ctx, which is per-CPU in zram). Not to mention that zstd_get_params(param->level, 0) is what we need at the end. And then drivers need to be re-implemented to support params. For example, crypto/lz4 should call LZ4_compress_fast() instead of LZ4_compress_default(), because fact() accepts compression level, which is a tunable value.
