42 lines
2 KiB
Text
42 lines
2 KiB
Text
[[!comment format=mdwn
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username="joey"
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subject="""more profiling"""
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date="2016-09-26T19:59:43Z"
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content="""
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Instead of profiling `git annex copy --to remote`, I profiled `git annex
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find --not --in web`, which needs to do the same kind of location log lookup.
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total time = 12.41 secs (12413 ticks @ 1000 us, 1 processor)
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total alloc = 8,645,057,104 bytes (excludes profiling overheads)
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COST CENTRE MODULE %time %alloc
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adjustGitEnv Git.Env 21.4 37.0
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catchIO Utility.Exception 13.2 2.8
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spanList Data.List.Utils 12.6 17.9
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parsePOSIXTime Logs.TimeStamp 6.1 5.0
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catObjectDetails.receive Git.CatFile 5.9 2.1
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startswith Data.List.Utils 5.7 3.8
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md5 Data.Hash.MD5 5.1 7.9
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join Data.List.Utils 2.4 6.0
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readFileStrictAnyEncoding Utility.Misc 2.2 0.5
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The adjustGitEnv overhead is a surprise! It seems it is getting called once
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per file, and allocating a new copy of the environment each time. Call stack:
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withIndex calls withIndexFile calls addGitEnv calls adjustGitEnv.
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Looks like simply making gitEnv be cached at startup would avoid most of
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the adjustGitEnv slowdown.
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(The catchIO overhead is a false reading; the detailed profile shows
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that all its time and allocations are inherited. getAnnexLinkTarget
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is running catchIO in the expensive case, so readSymbolicLink is
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the actual expensive bit.)
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The parsePOSIXTime comes from reading location logs. It's implemented
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using a generic Data.Time.Format.parseTime, which uses a format string
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"%s%Qs". A custom parser that splits into seconds and picoseconds
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and simply reads both numbers might be more efficient.
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catObjectDetails.receive is implemented using mostly String and could
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probably be sped up by being converted to use ByteString.
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"""]]
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