#8224: Excessive system time -- new IO manager problem? -------------------------------------+------------------------------------- Reporter: rrnewton | Owner: Type: bug | Status: new Priority: high | Milestone: 8.2.1 Component: Runtime System | Version: 7.7 Resolution: | Keywords: IO Manager, | System Time Operating System: Linux | Architecture: x86_64 Type of failure: Runtime | (amd64) performance bug | Test Case: Blocked By: | Blocking: Related Tickets: #9221 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by alkar): In previous post I used ghc-7.10.1 by mistake. With 8.0.1 (`stack ghc -- -O2 -rtsopts -threaded x`) single core performance is same (around `0.18s`), but with `+RTS -N` I get better results: {{{ real 0m0.843s user 0m22.149s sys 0m2.256s }}} Even better with `-A200M`: {{{ real 0m0.793s user 0m1.200s sys 0m0.692s }}} {{{ $ head -c10MB /dev/zero | ./x +RTS -s -N > /dev/null 406,012,416 bytes allocated in the heap 30,457,408 bytes copied during GC 674,776 bytes maximum residency (2 sample(s)) 665,248 bytes maximum slop 27 MB total memory in use (0 MB lost due to fragmentation) Tot time (elapsed) Avg pause Max pause Gen 0 775 colls, 775 par 16.945s 0.429s 0.0006s 0.0302s Gen 1 2 colls, 1 par 0.052s 0.002s 0.0012s 0.0013s Parallel GC work balance: 0.14% (serial 0%, perfect 100%) TASKS: 98 (1 bound, 97 peak workers (97 total), using -N48) SPARKS: 0 (0 converted, 0 overflowed, 0 dud, 0 GC'd, 0 fizzled) INIT time 2.660s ( 0.091s elapsed) MUT time 11.065s ( 0.744s elapsed) GC time 16.997s ( 0.432s elapsed) EXIT time 0.028s ( 0.003s elapsed) Total time 30.750s ( 1.270s elapsed) Alloc rate 36,694,519 bytes per MUT second Productivity 36.1% of total user, 873.3% of total elapsed gc_alloc_block_sync: 38774 whitehole_spin: 0 gen[0].sync: 408 gen[1].sync: 130 }}} I attached outputs of `lstopo` (I don't have -no-graphics variant there) and `numactl -H`. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8224#comment:32 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler