On Tue, Jan 19, 2021 at 04:33:50PM +0100, Borislav Petkov wrote: > On Tue, Jan 19, 2021 at 11:09:03PM +0800, Feng Tang wrote: > > Yes, that can happen. I started a 4 tasks netperf on a 4C/8T KBL desktop, > > and also saw around 2% improvement. Both the kernel config and the > > platform matters. > > Oh great. ;-\ > > > For the performance changes I have checked, sometimes the change can be > > reproduced on platforms of different generations (the exact delta number > > may differs), sometimes it can only be reproduced on one specific platform, > > like some old generation, or special one like Xeon Phi. > > Probably because that Xeon Phi thing is not as powerful cache-wise as > some newer ones which have bigger caches and smarter hw prefetchers, > etc.
Yes, cache size/architecture/policy plays a critical role in these benchmarking, which is our first thing to check for these strange kernel performance changes. Thanks, Feng
