On 10/02/2018 05:06 AM, Ingo Molnar wrote: > * Waiman Long <[email protected]> wrote: > >> Enabling CONFIG_LOCKDEP and other related debug options will greatly >> reduce system performance. This patchset aims to reduce the performance >> slowdown caused by the lockdep code. >> >> Patch 1 just removes an inline function that wasn't used. >> >> Patches 2 and 3 are minor twists to optimize the code. >> >> Patch 4 makes class->ops a per-cpu counter. >> >> Patch 5 moves the lock_release() call outside of a lock critical section. >> >> Parallel kernel compilation tests (make -j <#cpu>) were performed on >> 2 different systems: >> >> 1) an 1-socket 22-core 44-thread Skylake system >> 2) a 4-socket 72-core 144-thread Broadwell system >> >> The build times with pre-patch and post-patch debug kernels were: >> >> System Pre-patch Post-patch %Change >> ------ --------- ---------- ------- >> 1-socket 8m53.9s 8m41.2s -2.4% >> 4-socket 7m27.0s 5m31.0s -26% >> >> I think it is the last 2 patches that yield most of the performance >> improvement. > Impressive speedup! > > Mind including the non-lockdep numbers as well, for reference? > > Thanks, > > Ingo
OK, I will include the non lockdep number for comparison. However the debug kernel has other debugging code enabled as well so the slowdown won't be just for the enabling of lockdep. -Longman
