On 2018-07-25 11:54:53 [+0200], Ard Biesheuvel wrote: > Indeed. OTOH, if the -rt people (Sebastian?) turn up and say that a > 1000 cycle limit to the quantum of work performed with preemption > disabled is unreasonably low, we can increase the yield block counts > and approach the optimal numbers a bit closer. But with diminishing > returns. So I tested on SoftIron Overdrive 1000 which has A57 cores. I added this series and didn't notice any spikes. This means cyclictest reported a max value of like ~20us (which means the crypto code was not noticeable). I played a little with it and tcrypt tests for aes/sha1 and also no huge spikes. So at this point this looks fantastic. I also setup cryptsetup / dm-crypt with the usual xts(aes) mode and saw no spikes. At this point, on this hardware if you want to raise the block count, I wouldn't mind. I remember on x86 the SIMD accelerated ciphers led to ~1ms+ spikes once dm-crypt started its jobs. Sebastian
