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Subject: Average cost of the OCaml GC
From: Jianzhou Zhao <jianzhou@seas.upenn.edu>
To: caml-list@yquem.inria.fr
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X-Spam: no; 0.00; ocaml:01 ocaml:01 'self:01 'self:01 zhao:98 57%:98 57%:98 upenn:01 functions:01 functions:01 data:02 defined:02 21%:97 21%:97 profiling:04 

Hi,

What is the average cost of the OCaml GC? I have a program that calls
'mark_slice' in 57% of the total execution time, and calls
'sweep_slice' in 21% of the total time, reported by Callgrind, which
is a profiling tool in Valgrind. 57% and 21% are the 'self cost' ---
the cost of the function itself ('Self Cost'), rather than the cost
including all called functions ('Inclusive Cost'). I guess
'mark_slice'  and  'sweep_slice'  are functions from OCaml GC. Are
these numbers normal?

My program calls both OCaml and C, which passes around C data types in
between. I also doubt if I defined the interface in an 'unefficient'
way that slows down the GC. Are there any rules in mind to make GC
work more efficiently?

Thanks.
-- 
Jianzhou