The explanation is simple, the kernel is taking too long to run so the main loop is unable to calculate the speed. If you're still seeing 0 H/s with -w 1 or -n 1 -u 1024 then the GPU is simply too slow. If you're using EC2 this makes perfect sense as the GPUs that Amazon uses are terrible for password cracking.
Anyway, I thought this was rather obvious, but reporting 0 H/s is purely a cosmetic issue. It's simply a matter of UI responsiveness and doesn't impact your actual cracking speed.
Anyway, I thought this was rather obvious, but reporting 0 H/s is purely a cosmetic issue. It's simply a matter of UI responsiveness and doesn't impact your actual cracking speed.