I did try to write some MIPS32r2 code.
I wrote the chacha20_keysetup, chacha20_generic_block and
poly1305_generic_blocks in assembly.
Tried to load all needed variables in the registers. Which should
reduce the memory overhead.
But it is very difficult for me to do code profiling and/or isolate
the code and make some benchmark programs like supercop.
So testing was simple. Crosscompile the code. Copy and load the module
on the target. Run setup script and iperf.
#ifdef CONFIG_CPU_MIPS32_R2
asmlinkage void chacha20_keysetup(struct chacha20_ctx *ctx, const u8
key[static 32], const u8 nonce[static 8]);
asmlinkage void chacha20_generic_block(struct chacha20_ctx *ctx);
asmlinkage unsigned int poly1305_generic_blocks(struct poly1305_ctx
*ctx, const u8 *src, unsigned int srclen, u32 hibit);
#endif
But the speed is equal or less on my TP WR1043ND device which is a
MIPS32r2 24kc big endian.
So GCC does a good job. Also 24kc has no special CoProcessors or FPU.
Most improvement what I had it to change the buildroot default
optimization -Os to -O2.
This gives around 1-3% speed improvement.
ideas:
- remove the little endian parts on the MIPS.
Offcourse do it also on the other side.
On this device I can't switch endian.
But I did not see any improvements. Need 2 instruction for swapping
32bit register.
After a quick calculation it could save around 0.4% which is
~0.1MBit/s on this device.
Greats,
René van Dorst.
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