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Groups > comp.arch.embedded > #29573
| From | Niklas Holsti <niklas.holsti@tidorum.invalid> |
|---|---|
| Newsgroups | comp.arch.embedded |
| Subject | Re: Custom CPU Designs |
| Date | 2020-04-21 19:41 +0300 |
| Organization | Tidorum Ltd |
| Message-ID | <hg8m25FojujU1@mid.individual.net> (permalink) |
| References | (9 earlier) <871rolzzts.fsf@nightsong.com> <387c667c-ae86-413e-b973-65a3fb3db7fc@googlegroups.com> <r7kd1p$kum$1@dont-email.me> <869be946-a22c-4bd9-b3ef-d0180b960343@googlegroups.com> <r7n57f$mlr$1@dont-email.me> |
On 2020-04-21 18:58, David Brown wrote:
> On 21/04/2020 03:27, Rick C wrote:
>> On Monday, April 20, 2020 at 10:53:49 AM UTC-4, David Brown wrote:
[snip]
>>> Task prioritising is an important issue. But it is not just for
>>> multitasking on a single cpu. If you have a high priority task A that
>>> sometimes has to wait for the results from a low priority task B, you
>>> have an issue to deal with. That applies whether they are on the same
>>> cpu or different ones. On a single cpu, you have the solution of
>>> bumping up the priority for task B for a bit (priority inheritance) - on
>>> different cpus, you just have to wait.
There are similar multi-core priority-bumping schemes, but they are more
complex and have more overhead, of course.
>> How is that an issue? Isn't task A stalled when it is waiting which
>> allows task B to run?
>
> Yes. But it means task A - the high priority task - can't be completed
> as fast as you had wanted.
If there are no other tasks on this core, there is no extra delay for A
-- it waits just long enough for B to complete the/a result for A.
The real problem occurs when there is some other task C, _not_ logically
connected to A or B, with a priority higher than B but lower than A.
Task C can then delay B, and therefore also A, for whatever duration C
runs. As David said, this priority inversion can be solved by
temporarily increasing B's priority to A's priority until B has executed
far enough to let A continue.
In the Ada language, the "protected object" inter-task communication
mechanism implements this priority juggling automatically. The
programmer only has to define the basic task priorities and the "ceiling
priorities" for the protected objects.
--
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
. @ .
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Custom CPU Designs Rick C <gnuarm.deletethisbit@gmail.com> - 2020-04-15 20:51 -0700
Re: Custom CPU Designs Theo <theom+news@chiark.greenend.org.uk> - 2020-04-16 11:59 +0100
Re: Custom CPU Designs David Brown <david.brown@hesbynett.no> - 2020-04-16 13:28 +0200
Re: Custom CPU Designs Grant Edwards <invalid@invalid.invalid> - 2020-04-16 13:10 +0000
Re: Custom CPU Designs Theo <theom+news@chiark.greenend.org.uk> - 2020-04-16 22:16 +0100
Re: Custom CPU Designs Grant Edwards <invalid@invalid.invalid> - 2020-04-16 22:01 +0000
Re: Custom CPU Designs Paul Rubin <no.email@nospam.invalid> - 2020-04-16 17:13 -0700
Re: Custom CPU Designs jim.brakefield@ieee.org - 2020-04-16 18:10 -0700
Re: Custom CPU Designs Rick C <gnuarm.deletethisbit@gmail.com> - 2020-04-16 18:37 -0700
Re: Custom CPU Designs Paul Rubin <no.email@nospam.invalid> - 2020-04-16 22:08 -0700
Re: Custom CPU Designs David Brown <david.brown@hesbynett.no> - 2020-04-17 10:02 +0200
Re: Custom CPU Designs Tom Gardner <spamjunk@blueyonder.co.uk> - 2020-04-17 10:49 +0100
Re: Custom CPU Designs David Brown <david.brown@hesbynett.no> - 2020-04-17 15:44 +0200
Re: Custom CPU Designs Tom Gardner <spamjunk@blueyonder.co.uk> - 2020-04-17 15:23 +0100
Re: Custom CPU Designs David Brown <david.brown@hesbynett.no> - 2020-04-17 18:15 +0200
Re: Custom CPU Designs Tom Gardner <spamjunk@blueyonder.co.uk> - 2020-04-17 17:49 +0100
Re: Custom CPU Designs David Brown <david.brown@hesbynett.no> - 2020-04-18 15:06 +0200
Re: Custom CPU Designs Tom Gardner <spamjunk@blueyonder.co.uk> - 2020-04-18 16:08 +0100
Re: Custom CPU Designs David Brown <david.brown@hesbynett.no> - 2020-04-20 15:13 +0200
Re: Custom CPU Designs Tom Gardner <spamjunk@blueyonder.co.uk> - 2020-04-20 14:24 +0100
Re: Custom CPU Designs David Brown <david.brown@hesbynett.no> - 2020-04-20 16:00 +0200
Re: Custom CPU Designs Paul Rubin <no.email@nospam.invalid> - 2020-04-20 14:32 -0700
Re: Custom CPU Designs Tom Gardner <spamjunk@blueyonder.co.uk> - 2020-04-20 23:55 +0100
Re: Custom CPU Designs Reinhardt Behm <rbehm@hushmail.com> - 2020-04-21 15:14 +0800
Re: Custom CPU Designs Theo <theom+news@chiark.greenend.org.uk> - 2020-04-18 16:51 +0100
Re: Custom CPU Designs Tom Gardner <spamjunk@blueyonder.co.uk> - 2020-04-18 18:06 +0100
Re: Custom CPU Designs Rick C <gnuarm.deletethisbit@gmail.com> - 2020-04-18 14:53 -0700
Re: Custom CPU Designs Tom Gardner <spamjunk@blueyonder.co.uk> - 2020-04-19 10:11 +0100
Re: Custom CPU Designs upsidedown@downunder.com - 2020-04-19 13:19 +0300
Re: Custom CPU Designs Tom Gardner <spamjunk@blueyonder.co.uk> - 2020-04-19 11:33 +0100
Re: Custom CPU Designs David Brown <david.brown@hesbynett.no> - 2020-04-20 15:26 +0200
Re: Custom CPU Designs Tom Gardner <spamjunk@blueyonder.co.uk> - 2020-04-20 14:59 +0100
Re: Custom CPU Designs Rick C <gnuarm.deletethisbit@gmail.com> - 2020-04-19 13:37 -0700
Re: Custom CPU Designs Tom Gardner <spamjunk@blueyonder.co.uk> - 2020-04-19 22:02 +0100
Re: Custom CPU Designs Tom Gardner <spamjunk@blueyonder.co.uk> - 2020-04-19 22:15 +0100
Re: Custom CPU Designs Rick C <gnuarm.deletethisbit@gmail.com> - 2020-04-19 15:02 -0700
Re: Custom CPU Designs Tom Gardner <spamjunk@blueyonder.co.uk> - 2020-04-20 02:03 +0100
Re: Custom CPU Designs Rick C <gnuarm.deletethisbit@gmail.com> - 2020-04-18 14:44 -0700
Re: Custom CPU Designs David Brown <david.brown@hesbynett.no> - 2020-04-20 15:20 +0200
Re: Custom CPU Designs Tom Gardner <spamjunk@blueyonder.co.uk> - 2020-04-20 14:57 +0100
Re: Custom CPU Designs Rick C <gnuarm.deletethisbit@gmail.com> - 2020-04-18 12:38 -0700
Re: Custom CPU Designs David Brown <david.brown@hesbynett.no> - 2020-04-20 15:58 +0200
Re: Custom CPU Designs Tom Gardner <spamjunk@blueyonder.co.uk> - 2020-04-20 16:27 +0100
Re: Custom CPU Designs Rick C <gnuarm.deletethisbit@gmail.com> - 2020-04-20 17:36 -0700
Re: Custom CPU Designs David Brown <david.brown@hesbynett.no> - 2020-04-21 14:02 +0200
Re: Custom CPU Designs Rick C <gnuarm.deletethisbit@gmail.com> - 2020-04-21 06:15 -0700
Re: Custom CPU Designs David Brown <david.brown@hesbynett.no> - 2020-04-21 17:25 +0200
Re: Custom CPU Designs Tom Gardner <spamjunk@blueyonder.co.uk> - 2020-04-21 16:56 +0100
Re: Custom CPU Designs Rick C <gnuarm.deletethisbit@gmail.com> - 2020-04-21 12:42 -0700
Re: Custom CPU Designs Tom Gardner <spamjunk@blueyonder.co.uk> - 2020-04-21 23:16 +0100
Re: Custom CPU Designs David Brown <david.brown@hesbynett.no> - 2020-04-22 11:10 +0200
Re: Custom CPU Designs Rick C <gnuarm.deletethisbit@gmail.com> - 2020-04-22 08:09 -0700
Re: Custom CPU Designs David Brown <david.brown@hesbynett.no> - 2020-04-22 20:07 +0200
Re: Custom CPU Designs Paul Rubin <no.email@nospam.invalid> - 2020-04-18 13:09 -0700
Re: Custom CPU Designs Tom Gardner <spamjunk@blueyonder.co.uk> - 2020-04-18 21:28 +0100
Re: Custom CPU Designs upsidedown@downunder.com - 2020-04-21 20:29 +0300
Re: Custom CPU Designs Grant Edwards <invalid@invalid.invalid> - 2020-04-21 18:10 +0000
Re: Custom CPU Designs upsidedown@downunder.com - 2020-04-22 09:54 +0300
Re: Custom CPU Designs Grant Edwards <invalid@invalid.invalid> - 2020-04-22 13:19 +0000
Re: Custom CPU Designs upsidedown@downunder.com - 2020-04-22 18:09 +0300
Re: Custom CPU Designs Grant Edwards <invalid@invalid.invalid> - 2020-04-22 17:03 +0000
Re: Custom CPU Designs David Brown <david.brown@hesbynett.no> - 2020-04-22 11:16 +0200
Re: Custom CPU Designs Rick C <gnuarm.deletethisbit@gmail.com> - 2020-04-17 10:48 -0700
Re: Custom CPU Designs David Brown <david.brown@hesbynett.no> - 2020-04-18 16:57 +0200
Re: Custom CPU Designs Rick C <gnuarm.deletethisbit@gmail.com> - 2020-04-18 14:21 -0700
Re: Custom CPU Designs Paul Rubin <no.email@nospam.invalid> - 2020-04-18 14:50 -0700
Re: Custom CPU Designs David Brown <david.brown@hesbynett.no> - 2020-04-20 16:32 +0200
Re: Custom CPU Designs Rick C <gnuarm.deletethisbit@gmail.com> - 2020-04-20 18:12 -0700
Re: Custom CPU Designs Tom Gardner <spamjunk@blueyonder.co.uk> - 2020-04-21 10:09 +0100
Re: Custom CPU Designs Tom Gardner <spamjunk@blueyonder.co.uk> - 2020-04-20 16:31 +0100
Re: Custom CPU Designs Tom Gardner <spamjunk@blueyonder.co.uk> - 2020-04-20 16:42 +0100
Re: Custom CPU Designs upsidedown@downunder.com - 2020-04-18 00:43 +0300
Re: Custom CPU Designs David Brown <david.brown@hesbynett.no> - 2020-04-18 17:07 +0200
Re: Custom CPU Designs Rick C <gnuarm.deletethisbit@gmail.com> - 2020-04-17 09:11 -0700
Re: Custom CPU Designs Paul Rubin <no.email@nospam.invalid> - 2020-04-17 12:17 -0700
Re: Custom CPU Designs Rick C <gnuarm.deletethisbit@gmail.com> - 2020-04-17 13:22 -0700
Re: Custom CPU Designs Paul Rubin <no.email@nospam.invalid> - 2020-04-17 14:48 -0700
Re: Custom CPU Designs Rick C <gnuarm.deletethisbit@gmail.com> - 2020-04-17 15:27 -0700
Re: Custom CPU Designs David Brown <david.brown@hesbynett.no> - 2020-04-20 16:53 +0200
Re: Custom CPU Designs Tom Gardner <spamjunk@blueyonder.co.uk> - 2020-04-20 17:03 +0100
Re: Custom CPU Designs David Brown <david.brown@hesbynett.no> - 2020-04-20 19:39 +0200
Re: Custom CPU Designs Tom Gardner <spamjunk@blueyonder.co.uk> - 2020-04-20 21:25 +0100
Re: Custom CPU Designs Rick C <gnuarm.deletethisbit@gmail.com> - 2020-04-20 18:27 -0700
Re: Custom CPU Designs David Brown <david.brown@hesbynett.no> - 2020-04-21 17:58 +0200
Re: Custom CPU Designs Niklas Holsti <niklas.holsti@tidorum.invalid> - 2020-04-21 19:41 +0300
Re: Custom CPU Designs Rick C <gnuarm.deletethisbit@gmail.com> - 2020-04-21 14:01 -0700
Re: Custom CPU Designs Tom Gardner <spamjunk@blueyonder.co.uk> - 2020-04-21 23:21 +0100
Re: Custom CPU Designs David Brown <david.brown@hesbynett.no> - 2020-04-19 20:53 +0200
Re: Custom CPU Designs Rick C <gnuarm.deletethisbit@gmail.com> - 2020-04-19 14:47 -0700
Re: Custom CPU Designs Tom Gardner <spamjunk@blueyonder.co.uk> - 2020-04-20 02:11 +0100
Re: Custom CPU Designs Paul Rubin <no.email@nospam.invalid> - 2020-04-19 18:31 -0700
Re: Custom CPU Designs Rick C <gnuarm.deletethisbit@gmail.com> - 2020-04-19 20:32 -0700
Re: Custom CPU Designs Tom Gardner <spamjunk@blueyonder.co.uk> - 2020-04-20 07:46 +0100
Re: Custom CPU Designs Rick C <gnuarm.deletethisbit@gmail.com> - 2020-04-20 00:33 -0700
Re: Custom CPU Designs Tom Gardner <spamjunk@blueyonder.co.uk> - 2020-04-20 11:01 +0100
Re: Custom CPU Designs David Brown <david.brown@hesbynett.no> - 2020-04-20 17:44 +0200
Re: Custom CPU Designs Rick C <gnuarm.deletethisbit@gmail.com> - 2020-04-20 19:57 -0700
Re: Custom CPU Designs David Brown <david.brown@hesbynett.no> - 2020-04-21 18:02 +0200
Re: Custom CPU Designs Rick C <gnuarm.deletethisbit@gmail.com> - 2020-04-21 14:56 -0700
Re: Custom CPU Designs Theo <theom+news@chiark.greenend.org.uk> - 2020-04-17 16:34 +0100
Re: Custom CPU Designs David Brown <david.brown@hesbynett.no> - 2020-04-20 17:57 +0200
Re: Custom CPU Designs Theo <theom+news@chiark.greenend.org.uk> - 2020-04-21 15:20 +0100
Re: Custom CPU Designs Rick C <gnuarm.deletethisbit@gmail.com> - 2020-04-21 08:26 -0700
Re: Custom CPU Designs David Brown <david.brown@hesbynett.no> - 2020-04-21 18:09 +0200
Re: Custom CPU Designs Rick C <gnuarm.deletethisbit@gmail.com> - 2020-04-21 15:00 -0700
Re: Custom CPU Designs David Brown <david.brown@hesbynett.no> - 2020-04-22 11:28 +0200
Re: Custom CPU Designs Rick C <gnuarm.deletethisbit@gmail.com> - 2020-04-22 08:24 -0700
Re: Custom CPU Designs David Brown <david.brown@hesbynett.no> - 2020-04-22 20:18 +0200
Re: Custom CPU Designs Rick C <gnuarm.deletethisbit@gmail.com> - 2020-04-22 11:45 -0700
Re: Custom CPU Designs David Brown <david.brown@hesbynett.no> - 2020-04-23 17:47 +0200
Re: Custom CPU Designs jim.brakefield@ieee.org - 2020-04-21 15:35 -0700
Re: Custom CPU Designs Przemek Klosowski <przemek@tux.dot.org> - 2020-04-19 18:52 +0000
Re: Custom CPU Designs Rick C <gnuarm.deletethisbit@gmail.com> - 2020-04-19 13:42 -0700
Re: Custom CPU Designs Clifford Heath <no.spam@please.net> - 2020-04-20 22:59 +1000
Re: Custom CPU Designs Rick C <gnuarm.deletethisbit@gmail.com> - 2020-04-20 17:01 -0700
Re: Custom CPU Designs Clifford Heath <no.spam@please.net> - 2020-04-21 10:23 +1000
Re: Custom CPU Designs Rick C <gnuarm.deletethisbit@gmail.com> - 2020-04-21 03:47 -0700
Re: Custom CPU Designs Clifford Heath <no.spam@please.net> - 2020-04-22 09:26 +1000
Re: Custom CPU Designs Theo <theom+news@chiark.greenend.org.uk> - 2020-04-22 22:06 +0100
Re: Custom CPU Designs Rick C <gnuarm.deletethisbit@gmail.com> - 2020-04-22 14:18 -0700
Re: Custom CPU Designs Theo <theom+news@chiark.greenend.org.uk> - 2020-04-23 22:35 +0100
Re: Custom CPU Designs David Brown <david.brown@hesbynett.no> - 2020-04-21 18:20 +0200
Re: Custom CPU Designs Dimiter_Popoff <dp@tgi-sci.com> - 2020-04-22 18:16 +0300
Re: Custom CPU Designs Grant Edwards <invalid@invalid.invalid> - 2020-04-22 17:06 +0000
Re: Custom CPU Designs Dimiter_Popoff <dp@tgi-sci.com> - 2020-04-22 20:17 +0300
Re: Custom CPU Designs Grant Edwards <invalid@invalid.invalid> - 2020-04-22 17:28 +0000
Re: Custom CPU Designs George Neuner <gneuner2@comcast.net> - 2020-04-23 04:59 -0400
Re: Custom CPU Designs jim.brakefield@ieee.org - 2020-04-20 17:27 -0700
Re: Custom CPU Designs David Brown <david.brown@hesbynett.no> - 2020-04-20 17:58 +0200
Re: Custom CPU Designs pault.eg@googlemail.com - 2020-04-21 01:00 -0700
Re: Custom CPU Designs David Brown <david.brown@hesbynett.no> - 2020-04-21 19:21 +0200
Re: Custom CPU Designs Theo <theom+news@chiark.greenend.org.uk> - 2020-04-17 17:18 +0100
Re: Custom CPU Designs Rick C <gnuarm.deletethisbit@gmail.com> - 2020-04-16 07:40 -0700
Re: Custom CPU Designs jim.brakefield@ieee.org - 2020-04-16 12:28 -0700
Re: Custom CPU Designs Rick C <gnuarm.deletethisbit@gmail.com> - 2020-04-16 13:50 -0700
Re: Custom CPU Designs jim.brakefield@ieee.org - 2020-04-16 14:19 -0700
Re: Custom CPU Designs Theo <theom+news@chiark.greenend.org.uk> - 2020-04-16 22:33 +0100
Re: Custom CPU Designs Clifford Heath <no.spam@please.net> - 2020-04-17 11:29 +1000
Re: Custom CPU Designs Rick C <gnuarm.deletethisbit@gmail.com> - 2020-04-16 18:42 -0700
Re: Custom CPU Designs Clifford Heath <no.spam@please.net> - 2020-04-17 12:35 +1000
Re: Custom CPU Designs Rick C <gnuarm.deletethisbit@gmail.com> - 2020-04-16 20:01 -0700
Re: Custom CPU Designs Clifford Heath <no.spam@please.net> - 2020-04-17 14:54 +1000
Re: Custom CPU Designs Rick C <gnuarm.deletethisbit@gmail.com> - 2020-04-16 23:54 -0700
Re: Custom CPU Designs David Brown <david.brown@hesbynett.no> - 2020-04-17 10:38 +0200
Re: Custom CPU Designs Rick C <gnuarm.deletethisbit@gmail.com> - 2020-04-17 09:13 -0700
Re: Custom CPU Designs David Brown <david.brown@hesbynett.no> - 2020-04-20 18:02 +0200
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