A Case Against (Most) Context Switches

By: dmcq (dmcq.delete@this.fano.co.uk), May 19, 2021 1:47 pm
Room: Moderated Discussions
Little Horn (sink.delete@this.example.net) on May 17, 2021 5:03 pm wrote:
> Thoughts?

It doesn't seem to solve any reasonably big problem. It isn't something like capabilities for instance which would solve a host of problems and dramatically speed some important things up - albeit whilst introducng a few more problems :-)

Personally though I quite ike the idea of associating all the registers with an address space identifier rather than just it being used to help with caching memory - and call that a task identifier. The hardware could automatically swap in and out an entire task depending on the identifier. I don't think the hardware would be too difficult and would be reasonably efficient for small machines and there would be lots of room for optimisation for fast ones. I don't think the savings would be very dramatic but it simplifies the architectural model and makes it easier to extend.

Watching memory locations sounds far less like a solution to any real problem. It should just use the standard interrupt mechanism to send signals around with the addition of setting a task identifier. They have been optimised for the job and I don't see that this gives anything very desirable over and beyond that. Interrupts need not involve a function call - the handling could be treated more as a coprocessor call.
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TopicPosted ByDate
A Case Against (Most) Context SwitchesLittle Horn2021/05/17 05:03 PM
  A Case Against (Most) Context Switchesrwessel2021/05/17 06:55 PM
  A Case Against (Most) Context SwitchesFoo_2021/05/18 01:58 AM
    A Case Against (Most) Context SwitchesDoug S2021/05/18 08:45 AM
      A Case Against (Most) Context SwitchesKonrad Schwarz2021/05/19 07:35 AM
  A Case Against (Most) Context SwitchesEtienne Lorrain2021/05/18 03:11 AM
  A Case Against (Most) Context SwitchesAndrey2021/05/18 06:58 AM
  A Case Against (Most) Context Switchesgallier22021/05/18 08:41 AM
  A Case Against (Most) Context Switches---2021/05/18 09:00 AM
  A Case Against That Other PaperBrendan2021/05/18 12:37 PM
    A Case Against That Other PaperMark Roulo2021/05/18 03:32 PM
      A Case Against That Other PaperBrendan2021/05/18 11:05 PM
        A Case Against That Other PaperMark Roulo2021/05/19 01:09 PM
  A Case Against (Most) Context SwitchesRomain Dolbeau2021/05/19 04:05 AM
    A Case Against (Most) Context SwitchesBjörn Ragnar Björnsson2021/05/19 01:13 PM
      A Case Against ... authors show zero awareness of Cray-MTABjörn Ragnar Björnsson2021/05/19 06:18 PM
    Cray MTA avoided cachesPaul A. Clayton2021/05/20 06:36 AM
      Cray MTA avoided cachesdmcq2021/05/20 10:09 AM
        Cray MTA avoided cachesRayla2021/05/20 10:28 AM
      A LONG response to the paperPaul A. Clayton2021/05/22 06:15 AM
        A LONG response to the paperAdrian2021/05/22 09:18 AM
          Thank you for the note of appreciationPaul A. Clayton2021/05/24 05:06 AM
  A Case Against (Most) Context Switchesdmcq2021/05/19 01:47 PM
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