NetNews Offline 2/NetNews Offline Volume 2.iso/news/comp/sys/amiga/networking/3299

Internet Message Format | 1996-08-05 | 2.5 KB

Path: walrus.megabaud.fi!not-for-mail
From: [e-mail] (Petri Nordlund)
Newsgroups: comp.sys.amiga.networking
Subject: Re: Announce: AWeb 1.0 released!
Date: 31 Mar 1996 13:21:08 +0300
Organization: Megabaud Oy,Helsinki,Finland
Message-ID: <4jlmak$[e-mail]>
NNTP-Posting-Host: walrus.megabaud.fi

Jason S Birch ([e-mail]) writes:
>[e-mail] (Michael van Elst) writes:
>>[e-mail] (Jason S Birch) writes:
>>>Executive dynamically adjusts the priorities every second so that, over
>>>time, several CPU-intensive tasks (originally at the same priority)
>>>will indeed get equal amounts of CPU time.
>
>>That would mean that Executive always keeps the processes at the same
>>priority.
>
>Of course it doesn't. Over a long period of time they get the same
>amount of CPU (all else being equal), but in one second they can get
>vastly different amounts. Three CPU intensive processes will have
>their priorities raised, in turn, so that every three seconds one will
>get one seconds' worth of CPU.

  The "standard"-scheduler in Executive uses task's recent CPU usage
  (+load average and nice-value) to calculate a new priority for it.
  When one of these three CPU intensive tasks gets higher priority
  than others, it will use much more CPU time than the others, and
  when priorities are recalculated, its priority is dropped below
  the others. Then it will eventually migrate upwards from there.

  As I said in another message, the queues-scheduler does much better
  job on this. You can make the standard-scheduler work a bit like
  queues by making the dynamic priority range smaller. For example,
  DYNAMICMIN=-57 DYNAMICMAX=-50, would give eight priority levels
  for scheduled tasks. This will reduce the priority "wobbling",
  although the queues-scheduler has some additional features that
  try to minimize task migration between priority levels.

>>>Non-CPU intensive tasks
>>>are automatically raised in priority, because they are not using as
>>>much CPU.
>
>>And how would you handle processes that need a lot of CPU and are
>>scheduled a lot ?
>
>I would make an entry for them in Executive's preferences.

  Just give the task a higher nice-value, or if it has a window,
  Executive will automatically give it more CPU time, when the
  window is active.
--
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       Petri Nordlund             __///         [e-mail]
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