On (25/03/01 15:22), Herbert Xu wrote: > Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx> wrote: > > > > New API splits functions by access mode: > > - zs_obj_read_begin(handle, local_copy) > > Returns a pointer to handle memory. For objects that span two > > physical pages a local_copy buffer is used to store object's > > data before the address is returned to the caller. Otherwise > > the object's page is kmap_local mapped directly. > > I presume this buffer is always given to the compression algorithm > to decompress? In that case there should be no need to linearise > them at all. > > Just return a two-entry SG list, and give it to the Crypto API > to deal with. Both software and hardware algorithms can handle > non-linear input. Yes software decompression is currently > linearising all input with a copy, but that is no different > to the copy that you're making in zsmalloc. > > So please change this API to create an SG list instead of copying. > That way we can then optimise the software decompression to read > non-linear input directly and skip the copying altogether. A heads up: Discussed with Herbert privately, we will look into SG-list API later (future dev cycles).
