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From: "Steve Whalen" <SteveWhalen001@hotmail.com>
Newsgroups: comp.lang.ada
Subject: Re: task-safe hash table?
Date: 5 Jun 2006 14:57:16 -0700
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Date: 2006-06-05T14:57:16-07:00
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tmoran@acm.org wrote:
> > > the overhead of making it Protected would probably kill the gain.
> >
> > What "overhead"?
>    In a trivial single-tasking test program on my machine, a call to a
> Protected function compiled with Gnat 3.15p -O2 takes
>   0.304697000 mics while a call to a regular function takes
>   0.022779000 microseconds.
> Using -O3, it's
> 0.291347000 mics while a call to a regular function takes
> 0.001893000 microseconds.

When I run your program on a Linux Debian Sarge server with a vanilla
install of GNAT 3.15p with a slow 450mhz Pentium (and no other load) I
get:

==> compiled with no optimization <==
     a 0.076000000 mics
     b 0.075000000 mics
     c 0.073000000 mics
prot.a 3.590000000 mics
prot.b 2.480000000 mics
prot.c 1.710000000 mics

==> compiled with O2 optimization <==
     a 0.064000000 mics
     b 0.041000000 mics
     c 0.041000000 mics
prot.a 3.726000000 mics
prot.b 2.356000000 mics
prot.c 1.586000000 mics

==>  compiled with O3 optimization  <==
     a 0.017000000 mics
     b 0.017000000 mics
     c 0.006000000 mics
prot.a 3.820000000 mics
prot.b 2.369000000 mics
prot.c 1.865000000 mics

So the relationship between optimization levels looks materially the
same, as does the overhead of protected mode.

Steve