46 lines
1.9 KiB
Text
46 lines
1.9 KiB
Text
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[[!comment format=mdwn
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username="joey"
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subject="""profiling"""
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date="2016-09-26T19:20:36Z"
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content="""
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Built git-annex with profiling, using `stack build --profile`
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(For reproduciblity, running git-annex in a clone of the git-annex repo
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https://github.com/RichiH/conference_proceedings with rev
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2797a49023fc24aff6fcaec55421572e1eddcfa2 checked out. It has 9496 annexed
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objects.)
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Profiling `git-annex find +RTS -p`:
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total time = 3.53 secs (3530 ticks @ 1000 us, 1 processor)
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total alloc = 3,772,700,720 bytes (excludes profiling overheads)
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COST CENTRE MODULE %time %alloc
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spanList Data.List.Utils 32.6 37.7
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startswith Data.List.Utils 14.3 8.1
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md5 Data.Hash.MD5 12.4 18.2
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join Data.List.Utils 6.9 13.7
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catchIO Utility.Exception 5.9 6.0
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catches Control.Monad.Catch 5.0 2.8
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inAnnex'.checkindirect Annex.Content 4.6 1.8
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readish Utility.PartialPrelude 3.0 1.4
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isAnnexLink Annex.Link 2.6 4.0
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split Data.List.Utils 1.5 0.8
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keyPath Annex.Locations 1.2 1.7
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This is interesting!
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Fully 40% of CPU time and allocations are in list (really String) processing,
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and the details of the profiling report show that `spanList` and `startsWith`
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and `join` are all coming from calls to `replace` in `keyFile` and `fileKey`.
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Both functions nest several calls to replace, so perhaps that could be unwound
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into a single pass and/or a ByteString used to do it more efficiently.
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12% of run time is spent calculating the md5 hashes for the hash
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directories for .git/annex/objects. Data.Hash.MD5 is from missingh, and
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it is probably a quite unoptimised version. Switching to the version
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if cryptonite would probably speed it up a lot.
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"""]]
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