On Fri, Nov 09, 2018 at 02:59:18PM -0500, Steven Rostedt wrote: > On Fri, 9 Nov 2018 13:44:09 -0600 > Josh Poimboeuf <jpoim...@redhat.com> wrote: > > > On Fri, Nov 09, 2018 at 02:37:03PM -0500, Steven Rostedt wrote: > > > On Fri, 9 Nov 2018 11:05:51 -0800 > > > Andy Lutomirski <l...@amacapital.net> wrote: > > > > > > > > Not sure what Andy was talking about, but I'm currently implementing > > > > > tracepoints to use this, as tracepoints use indirect calls, and are a > > > > > prime candidate for static calls, as I showed in my original RFC of > > > > > this feature. > > > > > > > > > > > > > > > > > > Indeed. > > > > > > > > Although I had assumed that tracepoints already had appropriate jump > > > > label magic. > > > > > > It does. But that's not the problem I was trying to solve. It's that > > > tracing took a 8% noise dive with retpolines when enabled (hackbench > > > slowed down by 8% with all the trace events enabled compared to all > > > trace events enabled without retpoline). That is, normal users (those > > > not tracinng) are not affected by trace events slowing down by > > > retpoline. Those that care about performance when they are tracing, are > > > affected by retpoline, quite drastically. > > > > > > I'm doing another test run and measurements, to see how the unoptimized > > > trampolines help, followed by the trampoline case. > > > > Are you sure you're using unoptimized? Optimized is the default on > > x86-64 (with my third patch). > > > > Yes, because I haven't applied that third patch yet ;-) > > Then I'll apply it and see how much that improves things.
Ah, good. That will be interesting to see the difference between optimized/unoptimized. -- Josh
