On Mon, Nov 26, 2018 at 03:54:05PM -0500, Steven Rostedt wrote: > In summary, we had this: > > No RETPOLINES: > 1.4503 +- 0.0148 seconds time elapsed ( +- 1.02% ) > > baseline RETPOLINES: > 1.5120 +- 0.0133 seconds time elapsed ( +- 0.88% ) > > Added direct calls for trace_events: > 1.5239 +- 0.0139 seconds time elapsed ( +- 0.91% ) > > With static calls: > 1.5282 +- 0.0135 seconds time elapsed ( +- 0.88% ) > > With static call trampolines: > 1.48328 +- 0.00515 seconds time elapsed ( +- 0.35% ) > > Full static calls: > 1.47364 +- 0.00706 seconds time elapsed ( +- 0.48% ) > > > Adding Retpolines caused a 1.5120 / 1.4503 = 1.0425 ( 4.25% ) slowdown > > Trampolines made it into 1.48328 / 1.4503 = 1.0227 ( 2.27% ) slowdown > > With full static calls 1.47364 / 1.4503 = 1.0160 ( 1.6% ) slowdown > > Going from 4.25 to 1.6 isn't bad, and I think this is very much worth > the effort. I did not expect it to go to 0% as there's a lot of other > places that retpolines cause issues, but this shows that it does help > the tracing code. > > I originally did the tests with the development config, which has a > bunch of debugging options enabled (hackbench usually takes over 9 > seconds, not the 1.5 that was done here), and the slowdown was closer > to 9% with retpolines. If people want me to do this with that, or I can > send them the config. Or better yet, the code is here, just use your > own configs.
Thanks a lot for running these. This looks like a nice speedup. Also a nice reduction in the standard deviation. Should I add your tracepoint patch to the next version of my patches? -- Josh
