Hi Matteo, > > Marvell Armada 8040 - MACCHIATOBin Dual shot: > > > > $ dd if=/dev/zero bs=1G count=10 |time -p sha1sum > > a0b6e2ca4e28360a929943e8eb966f703a69dc44 2g.bin > > > > real 0m49.390s > > user 0m46.852s > > sys 0m2.076s > > $ dd if=/dev/zero bs=1G count=10 |time -p ./sha1sum-afalg > > a0b6e2ca4e28360a929943e8eb966f703a69dc44 2g.bin > > > > real 0m15.104s > > user 0m0.052s > > sys 0m15.008s
These are exciting speed improvements! > Linux kernel cryptographic API via the AF_ALG address family. Can you briefly explain: * <https://en.wikipedia.org/wiki/Crypto_API_(Linux)> says that on x86 platforms the same functions can be done through CPU instructions. Are these instructions privileged? If not, then what are - for this frequent case of Intel CPUs - the advantages and tradeoffs of user-space vs. kernel-space use of this crypto instructions? * What is the best way to detect that the Linux kernel support for this API is present? Is it that the socket(AF_ALG) call fails? Or is there some hint in the /proc/cpu or /proc/sys file system? A few hints regarding the gnulib coding style: * As you already noticed, we need to avoid build failures and runtime failures on platforms where this is not supported. * We don't use github, but this mailing list, for discussion and code reviews, as github is a proprietary and somewhat closed environment. * In the module description, section 'Include', you should not list all include files but only those that the user is supposed to include. In this case, I think, the af_alg business is invisible to the caller of the 4 modules. * In an include file, such as lib/af_alg.h, we include only the minimum of header files that are required for parsing it. In this case, I think it would only be <stdio.h>. The other header files can be included in the .c files, with the appropriate #if conditions. * The 'Hey Emacs!' section is only needed in files that contains non-ASCII characters. * Put '} else {' on 3 separate lines. * Use 'size_t', not 'int', for variables that denote the length of a memory segment. Bruno
