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Newsgroups: comp.lang.ada
Date: Mon, 23 Apr 2018 11:25:38 -0700 (PDT)
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Subject: Re: A question about task's select delay alternative
From: NiGHTS <nights@unku.us>
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Xref: reader02.eternal-september.org comp.lang.ada:51686
Date: 2018-04-23T11:25:38-07:00
List-Id: <comp.lang.ada>

On Monday, April 23, 2018 at 2:06:28 PM UTC-4, Jeffrey R. Carter wrote:
> On 04/23/2018 07:32 PM, NiGHTS wrote:
> >=20
> > What does "delay" actually do to the CPU? In this case I am using the A=
dacore GNAT compiler for a PC. Is it a loop constantly evaluating elapsed t=
ime? Or is it some kind of timed interrupt?
>=20
> What timed selective accept "does to the CPU" is not defined by the langu=
age.=20
> It's determined by the compiler implementation and, probably, by the feat=
ures of=20
> the OS, if any. So there's no Ada answer to your question.
>=20
> I don't know how GNAT implements this, but my experience with it is that =
blocked=20
> tasks don't use significant CPU. You can test this easily enough.
>=20
> Why do you care?
>=20
> --=20
> Jeff Carter
> "When danger reared its ugly head, he bravely
> turned his tail and fled."
> Monty Python and the Holy Grail
> 60

I have a number of busy threads I plan on launching, and I am wondering wha=
t cost I would incur launching them in parallel with watchdog threads. They=
 are used to monitor the busy threads for performance faults and have fail =
alternatives if the threads take too long.=20

I'd hate to bog down the CPU with unnecessary delays. Do I need to worry ab=
out lowering the CPU priority of such a non-essential thread in order to im=
prove overall system performance?