I replaced my slub changes with slub-local-lock-v2r3. I haven't seen any complains from lockdep or so which is good. Then I did this with RT enabled (and no debug): - A "time make -j32" run of allmodconfig on /dev/shm. Old: | real 20m6,217s | user 568m22,553s | sys 48m33,126s New: | real 20m9,049s | user 569m32,096s | sys 48m47,670s These 3 seconds here are probably in the noise range. - perf_5.10 stat -r 10 hackbench -g200 -s 4096 -l500 Old: | 464.967,20 msec task-clock # 27,220 CPUs utilized ( +- 0,16% ) | 7.683.944 context-switches # 0,017 M/sec ( +- 0,86% ) | 931.380 cpu-migrations # 0,002 M/sec ( +- 4,94% ) | 219.569 page-faults # 0,472 K/sec ( +- 0,39% ) | 1.104.727.599.918 cycles # 2,376 GHz ( +- 0,18% ) | 941.428.898.087 stalled-cycles-frontend # 85,22% frontend cycles idle ( +- 0,24% ) | 729.016.546.572 stalled-cycles-backend # 65,99% backend cycles idle ( +- 0,32% ) | 340.133.571.519 instructions # 0,31 insn per cycle | # 2,77 stalled cycles per insn ( +- 0,12% ) | 73.746.821.314 branches # 158,607 M/sec ( +- 0,13% ) | 377.838.006 branch-misses # 0,51% of all branches ( +- 1,01% ) | | 17,0820 +- 0,0202 seconds time elapsed ( +- 0,12% ) New: | 422.865,71 msec task-clock # 4,782 CPUs utilized ( +- 0,34% ) | 14.594.238 context-switches # 0,035 M/sec ( +- 0,43% ) | 3.737.926 cpu-migrations # 0,009 M/sec ( +- 0,46% ) | 218.474 page-faults # 0,517 K/sec ( +- 0,74% ) | 940.715.812.020 cycles # 2,225 GHz ( +- 0,34% ) | 716.593.827.820 stalled-cycles-frontend # 76,18% frontend cycles idle ( +- 0,39% ) | 550.730.862.839 stalled-cycles-backend # 58,54% backend cycles idle ( +- 0,43% ) | 417.274.588.907 instructions # 0,44 insn per cycle | # 1,72 stalled cycles per insn ( +- 0,17% ) | 92.814.150.290 branches # 219,488 M/sec ( +- 0,17% ) | 822.102.170 branch-misses # 0,89% of all branches ( +- 0,41% ) | | 88,427 +- 0,618 seconds time elapsed ( +- 0,70% ) So this is outside of the noise range. I'm not sure where this is coming from. My guess would be higher lock contention within the memory allocator. > The remaining patches to upstream from the RT tree are small ones related to > KConfig. The patch that restricts PREEMPT_RT to SLUB (not SLAB or SLOB) makes > sense. The patch that disables CONFIG_SLUB_CPU_PARTIAL with PREEMPT_RT could > perhaps be re-evaluated as the series also addresses some latency issues with > percpu partial slabs. With that series the PARTIAL slab can be indeed enabled. I have (had) a half done series where I had PARTIAL enabled and noticed a slight increase in latency so made it "default y on !RT". It wasn't dramatic but appeared to be outside of noise. Sebastian
