On Mon, Dec 05, 2022 at 11:21:51PM +0100, Daniel Borkmann wrote: > On 12/5/22 7:15 PM, Jason A. Donenfeld wrote: > > Since BPF's bpf_user_rnd_u32() was introduced, there have been three > > significant developments in the RNG: 1) get_random_u32() returns the > > same types of bytes as /dev/urandom, eliminating the distinction between > > "kernel random bytes" and "userspace random bytes", 2) get_random_u32() > > operates mostly locklessly over percpu state, 3) get_random_u32() has > > become quite fast. > > Wrt "quite fast", do you have a comparison between the two? Asking as its > often used in networking worst case on per packet basis (e.g. via XDP), would > be useful to state concrete numbers for the two on a given machine. Median of 25 cycles vs median of 38, on my Tiger Lake machine. So a little slower, but too small of a difference to matter.
