Excessive system time during execution of GHC-built executables on macOS
It seems that the executables built by GHC on my configuration of macOS are slow, clocking in 80% of my machine's cycles in system time.
Here is what I know.
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Everything tested bootstrapping with both GHC 8.6.1 and GHC 8.6.2. There is no observable difference between these bootstrapping compilers. The detailed data reported is all from GHC 8.6.1.
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When I try to build GHC, stage 1 builds snappily. But once stage-1 gets used, it slows to a crawl.
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Activity Monitor reports that my computer is spending roughly 80% of its time in the System space, not the User space. (While building ghc-stage1 itself, there is barely any system activity.)
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I have sampled ghc-stage1 during a rts_dist_HC call. Samples are at https://gist.github.com/goldfirere/7316920ad37d776c25c15dbb0ed5996f
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I then
dtruss
d the same, with output at https://gist.github.com/goldfirere/621ce9072e1204d30e96e7daecc80d02 -
System information:
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macOS High Sierra, 10.13.6
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Processor: 3.5 GHz Intel Core i5
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Memory: 16 GB 2400 MHz DDR4
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SSD main storage, formatted with APFS
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happy 1.19.9
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alex 3.2.4
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XCode 10.1
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gcc is clang-1000.11.45.5, Apple LLVM version 10.0.0, thread model: posix
Others (see thread) have not been able to repro, but this is very reliable for me.
Any ideas?
Trac metadata
Trac field | Value |
---|---|
Version | 8.6.2 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |