Hi! On Tue, Nov 05, 2019 at 10:14:46AM +0800, Kewen.Lin wrote: > >> + benefits were observed on Power8 and up, we can unify it if similar > >> + profits are measured on Power6 and Power7. */ > >> + if (TARGET_P8_VECTOR) > >> + return 2; > >> + else > >> + return 1; > > > > Hrm, but you showed benchmark improvements for p9 as well? > > > > No significant gains but no degradation as well, so I thought it's fine to > align > it together. Does it make sense?
It's a bit strange at this point to do tunings for p8 that do we do not do for later cpus. > > What happens if you enable this for everything as well? > > My concern was that if we enable it for everything, it's possible to introduce > degradation for some benchmarks on P6 or P7 where we didn't evaluate the > performance impact. No one cares about p6. We reasonably expect it will work just as well on p7 as on p8 and later. That you haven't tested on p7 yet says something about how important that platform is now ;-) > Although it's reasonable from the point view of load latency, > it's possible to get worse result in the actual benchmarks based on my fine > grain > cost adjustment experiment before. > > Or do you suggest enabling it everywhere and solve the degradation issue if > exposed? > I'm also fine with that. :) Yeah, let's just enable it everywhere. Segher
