On Tue, Nov 3, 2020 at 6:29 PM Kees Cook <keescook@xxxxxxxxxxxx> wrote: > Yeah, this is very interesting. That there is anything measurably _slower_ > with the cache is surprising. Though with only 4 runs, I wonder if it's > still noisy? What happens at 10 runs -- more importantly what is the > standard deviation? I could do that. it just takes such a long time. Each run takes about 20 minutes so with 10 runs per environment, 3 environments (native + 2 docker) per boot, and 4 boots (2 bootparam * 2 compile config), it's 27 hours of compilation. I should probably script it at that point. > I assume this is from Indirect Branch Prediction Barrier (IBPB) and > Single Threaded Indirect Branch Prediction (STIBP) (which get enabled > for threads under seccomp by default). > > Try booting with "spectre_v2_user=prctl" Hmm, to make sure, boot with just "spectre_v2_user=prctl" on the command line and test the performance of that? YiFei Zhu
