#15418: Performance drop 60 times on non-profiling binary -------------------------------------+------------------------------------- Reporter: hth313 | Owner: (none) Type: bug | Status: new Priority: high | Milestone: 8.6.1 Component: Runtime System | Version: 8.4.3 Resolution: | Keywords: Operating System: MacOS X | Architecture: x86_64 Type of failure: Runtime | (amd64) performance bug | Test Case: Blocked By: | Blocking: Related Tickets: #14414, #9599 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by hth313): Trying some low-tech profiling I compiled with `-debug` and ran in `lldb`, then stop using ctrl-c from time to time to see what it was up to. The following two are definitely main offenders, especically the second one. The first is the garbage collector in some way, I am not really sure what is going on in the second. {{{ * thread #1, queue = 'com.apple.main-thread', stop reason = signal SIGSTOP * frame #0: 0x000000010097d553 tcc6502`countBlocks(bd=0x0000004202400fc0) at BlockAlloc.c:782 frame #1: 0x0000000100988cd6 tcc6502`genBlocks(gen=0x0000000110c07528) at Sanity.c:870 frame #2: 0x0000000100988fff tcc6502`memInventory(show=false) at Sanity.c:900 frame #3: 0x00000001009821b8 tcc6502`GarbageCollect(collect_gen=0, do_heap_census=false, gc_type=0, cap=0x0000000101dc4500, idle_cap=0x0000000000000000) at GC.c:297 frame #4: 0x00000001009730b9 tcc6502`scheduleDoGC(pcap=0x00007ffeefbff770, task=0x0000000110c078a0, force_major=false) at Schedule.c:1809 frame #5: 0x00000001009724d4 tcc6502`schedule(initialCapability=0x0000000101dc4500, task=0x0000000110c078a0) at Schedule.c:558 frame #6: 0x00000001009737d8 tcc6502`scheduleWaitThread(tso=0x0000004200105388, ret=0x0000000000000000, pcap=0x00007ffeefbff870) at Schedule.c:2544 frame #7: 0x000000010096a496 tcc6502`rts_evalLazyIO(cap=0x00007ffeefbff870, p=0x0000000101d74e68, ret=0x0000000000000000) at RtsAPI.c:530 frame #8: 0x000000010096d448 tcc6502`hs_main(argc=7, argv=0x00007ffeefbff9c8, main_closure=0x0000000101d74e68, rts_config=RtsConfig @ 0x00007ffeefbff890) at RtsMain.c:72 frame #9: 0x000000010063eec6 tcc6502`main + 166 frame #10: 0x00007fff692ec015 libdyld.dylib`start + 1 frame #11: 0x00007fff692ec015 libdyld.dylib`start + 1 }}} {{{ frame #0: 0x00000001001105c4 tcc6502`c5kzn_info + 36 tcc6502`c5kzn_info: -> 0x1001105c4 <+36>: leaq 0x888175(%rip), %rdx ; stg_MUT_ARR_PTRS_DIRTY_info 0x1001105cb <+43>: movq %rdx, (%rbx) 0x1001105ce <+46>: leaq 0x18(%rbx), %rdx 0x1001105d2 <+50>: shrq $0x7, %rax Target 0: (tcc6502) stopped. (lldb) bt * thread #1, queue = 'com.apple.main-thread', stop reason = signal SIGSTOP * frame #0: 0x00000001001105c4 tcc6502`c5kzn_info + 36 frame #1: 0x0000000109a19b60 libclang.dylib`llvm::TargetLibraryInfoImpl::StandardNames + 896 frame #2: 0x0000000108a6440b libclang.dylib frame #3: 0x0000000101d3f8c1 tcc6502`TranslatorziTargetziMOS6502ziCompilerziRegister_RCzuY_closure + 1 }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15418#comment:11 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler