On 08/23/2016 10:46 PM, Corentin LABBE wrote:
Hello+/* Read data from the RNG unit */ +static int cavium_rng_read(struct hwrng *rng, void *dat, size_t max, bool wait) +{ + struct cavium_rng *p = container_of(rng, struct cavium_rng, ops); + unsigned int size = max; + + while (size >= 8) { + *((u64 *)dat) = readq(p->result); + size -= 8; + dat += 8; + }I think you could use readsq() This will increase throughput
If you look at the implementation of readsq(), you will see that it is a similar loop. Since the overhead is primarily I/O latency from the RNG hardware, the throughput cannot really be changed with micro optimizations to this simple loop.
Also, on big-endian kernels, it appears that a loop of readq() and readsq() will give different results as readq will byte swap the result and readsq does not. Since this is a RNG, the byte swapping is not important, but it is a difference.
Because of this, I think it should be acceptable to stick with the loop we currently have.
If the hwrng maintainers want to change the loop, to a readsq(), we might investigate this more.
Thanks, David Daney -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
