Hello! (If you’re in a hurry, there are good news at the bottom.) I noticed that 3.0 (and also 2.2 actually) takes a long time to compile Guix’ gnu/services/mail.scm, which is macro-heavy, producing lots of top-level defines. At -O2 (the default), we have: --8<---------------cut here---------------start------------->8--- scheme@(guile-user)> ,pr (compile-file "gnu/services/mail.scm") % cumulative self time seconds seconds procedure 13.79 19.16 14.46 language/cps/slot-allocation.scm:846:19 11.05 11.58 11.58 language/cps/intmap.scm:396:0:intmap-ref 7.56 12.63 7.92 anon #x10768e0 6.61 7.70 6.92 ice-9/popen.scm:145:0:reap-pipes 5.50 182.23 5.76 language/cps/intset.scm:470:5:visit-branch 4.65 4.87 4.87 system/vm/linker.scm:179:0:string-table-intern! 4.07 5.04 4.26 ice-9/vlist.scm:534:0:vhash-assoc 3.54 3.93 3.71 language/cps/intmap.scm:184:0:intmap-add! 3.28 6.65 3.43 language/cps/intset.scm:270:2:adjoin 2.70 2.82 2.82 language/cps/intset.scm:349:0:intset-ref 1.80 34.84 1.88 language/cps/intmap.scm:247:2:adjoin 1.80 5.93 1.88 language/cps/intset.scm:269:0:intset-add 1.74 18.22 1.83 language/cps/intmap.scm:246:0:intmap-add 1.22 3.27 1.27 language/cps/intset.scm:382:2:visit-node 1.16 2.94 1.22 language/cps/intset.scm:551:2:union 1.11 1.38 1.16 language/cps/intset.scm:204:0:intset-add! 0.74 1281.59 0.78 language/cps/intset.scm:472:5:visit-branch [...] Sample count: 1892 Total time: 104.795540582 seconds (85.091574653 seconds in GC) --8<---------------cut here---------------end--------------->8--- At -O1: --8<---------------cut here---------------start------------->8--- scheme@(guile-user)> ,use(system base optimize) scheme@(guile-user)> ,pr (compile-file "gnu/services/mail.scm" #:opts (optimizations-for-level 1)) % cumulative self time seconds seconds procedure 11.76 129.78 7.60 language/cps/intset.scm:470:5:visit-branch 10.77 6.96 6.96 language/cps/intmap.scm:396:0:intmap-ref 10.43 11.69 6.74 language/cps/slot-allocation.scm:846:19 8.99 7.39 5.81 ice-9/vlist.scm:534:0:vhash-assoc 7.55 4.88 4.88 system/vm/linker.scm:179:0:string-table-intern! 6.44 4.16 4.16 ice-9/popen.scm:145:0:reap-pipes 4.22 2.80 2.72 language/cps/intmap.scm:184:0:intmap-add! 1.89 1.86 1.22 language/cps/slot-allocation.scm:681:17 1.89 1.43 1.22 ice-9/vlist.scm:539:0:vhash-assq 1.78 1.51 1.15 language/cps/slot-allocation.scm:505:17 1.22 1.36 0.79 language/cps/slot-allocation.scm:846:19 1.22 1.08 0.79 language/cps/slot-allocation.scm:505:17 [...] Sample count: 901 Total time: 64.602907835 seconds (55.87541493 seconds in GC) --8<---------------cut here---------------end--------------->8--- language/cps/slot-allocation.scm:846:19 corresponds to: (define (compute-live-slots* slots label live-vars) (intset-fold (lambda (var live) (match (get-slot slots var) (#f live) (slot (add-live-slot slot live)))) ;L846 (intmap-ref live-vars label) 0)) The GC times remain extremely high though, and it’s also coming from ‘compute-live-slots*’: --8<---------------cut here---------------start------------->8--- scheme@(guile-user)> (gcprof (lambda () (compile-file "gnu/services/mail.scm" #:opts (optimizations-for-level 1)))) % cumulative self time seconds seconds procedure 58.14 34.56 34.56 language/cps/slot-allocation.scm:846:19 8.01 4.76 4.76 language/cps/slot-allocation.scm:681:17 8.01 4.76 4.76 language/cps/slot-allocation.scm:505:17 6.98 4.15 4.15 language/cps/slot-allocation.scm:505:17 6.46 3.84 3.84 language/cps/slot-allocation.scm:846:19 1.29 0.77 0.77 anon #x23e88e0 [...] Sample count: 387 Total time: 59.442422179 seconds (50.331193744 seconds in GC) --8<---------------cut here---------------end--------------->8--- (I believe Guile commit 5675e46410c9a24b05ddf58cbe3b998a4c9cad7c and its parent were made to optimize the -O1 case back in 2017¹.) ‘compute-live-slots*’ returns an integer and the allocation comes from line 846, where we allocate a bignum, in this case a verybignum even. And for each bignum, we register a finalizer, which itself takes space. (Time passes…) The patch below (also for 2.2) gives us better timing: --8<---------------cut here---------------start------------->8--- scheme@(guile-user)> (gcprof (lambda () (compile-file "gnu/services/mail.scm" #:opts (optimizations-for-level 1)))) % cumulative self time seconds seconds procedure 18.75 2.49 2.49 anon #x6f58e0 [...] Sample count: 32 Total time: 13.290191232 seconds (4.584969888 seconds in GC) --8<---------------cut here---------------end--------------->8--- … but has the disadvantage that it doesn’t work: ‘numbers.test’ fails badly on bignums. However, it turns out that removing the ‘mp_set_memory_functions’ call works, and the result is: --8<---------------cut here---------------start------------->8--- scheme@(guile-user)> (gcprof (lambda () (compile-file "gnu/services/mail.scm" #:opts (optimizations-for-level 1)))) % cumulative self time seconds seconds procedure 20.00 2.60 2.60 anon #x12578e0 10.00 3.47 1.30 language/cps/intset.scm:270:2:adjoin 6.67 0.87 0.87 ice-9/boot-9.scm:2201:0:%load-announce 6.67 0.87 0.87 anon #x1253160 3.33 146.48 0.43 ice-9/threads.scm:388:4 3.33 1.30 0.43 language/cps/intset.scm:759:8:lp 3.33 0.87 0.43 system/vm/assembler.scm:2854:4:write-die 3.33 0.43 0.43 language/cps/slot-allocation.scm:843:19 3.33 0.43 0.43 language/cps/intmap.scm:167:0:persistent-intmap [...] Sample count: 30 Total time: 13.001181844 seconds (4.278418897 seconds in GC) --8<---------------cut here---------------end--------------->8--- It’s 4.5 times faster than what we have now. Andy, anything against removing that ‘mp_set_memory_functions’ call altogether, or having ‘scm_install_gmp_memory_functions’ default to 0? Thanks, Ludo’. ¹ https://lists.gnu.org/archive/html/guile-devel/2017-10/msg00048.html