comments

doc/todo/--debug-level___40__and__47__or_-c_annex.debug-level__41___+_more_debug_information_from_git-annex/comment_4_03cd162638a9b4f2b7981cee141693f6._comment

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+[[!comment format=mdwn
+ username="joey"
+ subject="""comment 4"""
+ date="2021-04-02T16:09:45Z"
+ content="""
+I benchmarked calls to debugM when no debug output is enabled,
+and it looks like around 1 million can be made per second
+on my netbook. So if a 1% slowdown due to debugging is acceptable (which
+seems a bit above the upper bound to me), that would allow 10 thousand
+debugM calls per second.
+
+Current call rate is probably always under 10 per second. Keeping it
+out of tight loops would probably be sufficient.
+
+Once place I sometimes wish had debugging is reads from the git-annex
+branch. But running eg "git-annex get --from foo" in a repository with
+many thousands of files, none of them in foo, does tends of 
+thousands of reads per second in a tight loop. Benchmarked
+that command with debugM of reads added, and it was 0.05% slower
+than without debugM.
+
+So, to add debugM there, would need to do what comment #3 discussed.
+"""]]

doc/todo/--debug-level___40__and__47__or_-c_annex.debug-level__41___+_more_debug_information_from_git-annex/comment_5_f27efaef3d9cb8db3de9dd42df252059._comment

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+[[!comment format=mdwn
+ username="joey"
+ subject="""comment 5"""
+ date="2021-04-02T17:31:57Z"
+ content="""
+Re comment #3, it occurs to me that currently anything that accesses
+AnnexState does an MVar access, which will have around the same overhead as
+a call to debugM. But much more frequently used.
+
+So, anything in AnnexState that is frequently used and is immutable
+and could be split out to Reader will avoid that MVar access and be a
+free performance win. Good reason to split AnnexState, whether or not
+it's used to speed debugging.
+"""]]