On 14 May 2014 04:39, Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> wrote: > Dmitry Kasatkin <dmitry.kasatkin@xxxxxxxxx> wrote: >> Hi, >> >> ahash allows to use HW acceleration, but usually it comes at a cost of >> additional HW related configuration overhead, such as configuring hash >> module, DMA, etc. For that reason hashing small chucks of data is >> faster doing it with shash (CPU) rather than HW acceleration. >> >> I measured long time ago on omap-sham driver but cannot recall any data. >> >> Does anyone have any experience under what data size it is still >> better to use shash? > > It's going to be hardware-specific. It'll also depend on whether > you're coming from user-space or not as that would entail a bigger > per-request overhead, meaning that you need more data to break > even. > > Cheers, > -- > Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> > Home Page: http://gondor.apana.org.au/~herbert/ > PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt Thanks for the reply. Integrity subsystem hashing files and file sizes of course are much different. It is nice to minimize overall hashing time. I made a patch for ahash support, but without removing shash. It defines kernel command line parameter for file size threshold when start using ahash. It may be adjusted/tuned based on the particular HW. http://git.kernel.org/cgit/linux/kernel/git/kasatkin/linux-digsig.git/commit/?h=ima-experimental&id=85189d1265da83c4a5c537071b1fe4cddec59a54 -Dmitry -- To unsubscribe from this list: send the line "unsubscribe linux-crypto" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
