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Message from discussion Shared vs non shared PMC timings
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Leopold Toetsch  
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 More options Jan 20 2004, 12:00 pm
Newsgroups: perl.perl6.internals
From: l...@toetsch.at (Leopold Toetsch)
Date: Tue, 20 Jan 2004 17:48:19 +0100
Local: Tues, Jan 20 2004 11:48 am
Subject: Shared vs non shared PMC timings
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To estimate the costs of shared PMCs I have run this program[1], once
with .Ref and once with .SharedRef.

There are 2 major issues:
1) PMC initialization (new_p_ic_p): The shared PMC needs additionally
the allocation of the synchronize structure and the MUTEX_INIT.
2) PMC access (set_p_i): locking/unlocking the mutex

Here are snippets from the profile:

with SharedRef
  CODE  OP FULL NAME            CALLS  TOTAL TIME   AVG T. ms
  ----  -----------------     -------  ----------  ----------
   753  new_p_ic_p             100000    0.157785      0.0016
   905  set_p_i                100000    0.049269      0.0005

with Ref
  CODE  OP FULL NAME            CALLS  TOTAL TIME   AVG T. ms
  ----  -----------------     -------  ----------  ----------
   753  new_p_ic_p             100000    0.051330      0.0005
   905  set_p_i                100000    0.011356      0.0001

(Overall timings aren't really comparable, the SharedRef also does a
LOCK for mark, which slows that down as well)

Linux 2.2.16, Athlon 800, unoptimized Parrot build.
leo

[1]
      set I0, 100000
      set I1, 0
lp:
      new P0, .PerlInt
      new P1, .Ref, P0  # or .SharedRef
      set P1, I1
      inc I1
      lt I1, I0, lp
      end


 
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