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06-03-2009, 08:33 AM
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#46 | | Bernhard Strobl
Join Date: Dec 2007 Location: Immenstadt, Germany
Posts: 149
 | Quote: | Originally Posted by Pgr Threads and tasks aren't that different, and both multitasking and multithreading are possible on single CPU's. Of course, you have to understand that on a single CPU things aren't happening strictly at the same time, but as far as the programmer is concerned, they are, since the OS takes care of timeslicing the CPU so that the appearance of multiple execution occurs.
This effect is much more important to computer science (it's a powerful new model) than the subsequent application of multi-core processors or multiprocessors (which basically only adds to the efficiency of execution).
DGOS will be able to multitask and to multithread, because it is being written in the 21st century by a person who is not an idiot. It won't require multiple cores or processors to do this.
PS - the difference between threads and tasks (or processes) is that a task can subdivide in multiple courses of execution called threads. The main difference in handling these is related to memory isolation (tasks are not supposed to see or change other tasks' memory, threads often need to share memory with other threads of their own task, because they were written by the same developer, and are working on the same thing).
In Windows NT/2k/XP/Vista/7 (and possibly in other OS's, I don't know) the sheduler only schedules threads, it doesn't really bother which process they belong to. That only becomes relevant in issues of memory sharing and synchronization.
I hope this helps, or maybe I've just left you all more  ... |
We are discussing the likely consequences of having multi-threading on a single-core cpu for each process/task. Since each thread will have the overhead of the cpu having to switch register contents there can be a performance penalty.
It does give the programmer the ability to split the program at hand, but if there are dependencies it will just lead to stalls in one thread. | 
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06-03-2009, 09:09 AM
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#47 | | My T|X loves this site!
Join Date: Feb 2007
Posts: 613
| Quote: | Originally Posted by Bla8 We are discussing the likely consequences of having multi-threading on a single-core cpu for each process/task. Since each thread will have the overhead of the cpu having to switch register contents there can be a performance penalty.
It does give the programmer the ability to split the program at hand, but if there are dependencies it will just lead to stalls in one thread. |
Sure, this is how PC's have been running from between 1986 (Intel 80386) to about 3-4 years ago when multi-core processors started getting popular.
As an example, a Windows Vista on a single core processor is currently running 64 processes composed of 805 threads. The CPU usage is around 0%. All of these are just waiting for something to happen, 99.99% of the time...
Multithreading might reduce performance of very simplistic single-task processor-intensive applications, which is a very theoretical scenario.
It dramatically increases performance in real-life scenarios where lots of things are happening at the same time, and it's important to keep things going for one task while others wait for events.
The task-switch performance penalty is very insignificant compared to the advantages of making good use of dead wait times and the reduction in complexity of programming (I can think of my task as independent from all the others).
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06-03-2009, 01:38 PM
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#48 | | Bernhard Strobl
Join Date: Dec 2007 Location: Immenstadt, Germany
Posts: 149
| Quote: | Originally Posted by Pgr Sure, this is how PC's have been running from between 1986 (Intel 80386) to about 3-4 years ago when multi-core processors started getting popular.
As an example, a Windows Vista on a single core processor is currently running 64 processes composed of 805 threads. The CPU usage is around 0%. All of these are just waiting for something to happen, 99.99% of the time...
Multithreading might reduce performance of very simplistic single-task processor-intensive applications, which is a very theoretical scenario.
It dramatically increases performance in real-life scenarios where lots of things are happening at the same time, and it's important to keep things going for one task while others wait for events.
The task-switch performance penalty is very insignificant compared to the advantages of making good use of dead wait times and the reduction in complexity of programming (I can think of my task as independent from all the others). |
I'm not saying that the use of multi-threaded processes is a bad thing, its not  . I am just pointing out that things such as video decoding or other high performance apps should stick to one thread to prevent frequent switching of the registry information which will most likely need to be done by the OS Kernel itself. We are talking about one application and its associated threads, not the whole OS which can use several threads for its system services. | |
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06-03-2009, 02:08 PM
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#49 | | Software engineer/hacker
Join Date: Jan 2004 Location: Silicon Valley, CA
Posts: 5,061
| Context switching between threads of the same app is EXTREMELY cheap(fast) in DGOS.
__________________ Annoying me is NOT an approved way of encouraging me to produce software My software:PowerSDHC, PowerDrive, nuRom, UDMH, warpSpeed, PowerDiGi, brightnessFix, etc... Get it all here:http://www.PalmPowerups.com | |
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06-03-2009, 02:18 PM
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#50 | | My T|X loves this site!
Join Date: Feb 2007
Posts: 613
| @Dmitry
I think it's a miracle if you can pull off this DGOS project by yourself, but here goes my 2 cents... to show I have faith in miracles...
Two things I would like to see considered in a new OS for mobile devices:
1- NvBackup is a killer app. Its sole existence brings me freedom to try new software without worries (or stupid certificates and app stores), to play with my device and ruin it anyway I want, to never worry about viruses (or have to install anti-virus programs)...
Please make sure your system is ready for low-level 100%-safe backup and restore. Think how you could make it any better. For example, if the file system allowed for some extra flags for me to specify which files to backup, or how frequently, so that I could better manage the size of backups (avoiding an everyday copy of all my movies and mp3's, for example).
Make DGOS a system that can revert to earlier states - this, I believe, is the best solution (when possible) to avoid most of the security paranoias out there.
2- Apt is a killer app. Please make sure your system has a nice vocabulary of system settings, events and actions that are exposed consistently, not only through the UI, but also programatically. Make DGOS the most scriptable macroble system ever made. I believe this is useful for every OS, but especially convenient on small mobile devices, where sometimes supreme bliss is found by saving a pen tap, or being able to use a button instead of a menu option. Power to the user, not just to the developer! We're all becoming geeks anyway.
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06-03-2009, 02:33 PM
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#51 | | Apt? Yes, it can do that!
Join Date: Sep 2005 Location: CT, USA
Posts: 743
| Excellent comments Pgr! I agree completely. Wouldn't it be awesome if NVBackup and RescoBackup type apps could run in the background? I run NVB at 4am, so it's no big deal, but it takes about 20 minutes to do it's thing... I can't wait to see what DGOS can do. | |
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06-19-2009, 07:41 AM
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#52 | | Registered User
Join Date: Apr 2005
Posts: 1,119
| I see the blog everyday & this is moving fast!
Great,Great,Great! | |
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06-20-2009, 07:47 AM
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#53 | | Registered User
Join Date: May 2008 Location: Australia
Posts: 63
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Dmitry, I am really excited about DGOS, I was just wondering whether this would be possible? 
I love the Treo Pro hardware and am over my Centro hardware, I would love to run DGOS on the TP. It would be sick if you could do the not-possible-for-PalmOS and combine 3G(UMTS?)/wifi/bluetooth. It would be good for the OSs longevity too. *hoping so hard right now... | |
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06-20-2009, 09:12 AM
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#54 | | Registered User
Join Date: Nov 2007
Posts: 64
| Waiting DGOS too! | |
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06-20-2009, 01:17 PM
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#55 | | Software engineer/hacker
Join Date: Jan 2004 Location: Silicon Valley, CA
Posts: 5,061
| I haven't written any phone hardware drivers, and wan't planning on it just yet
__________________ Annoying me is NOT an approved way of encouraging me to produce software My software:PowerSDHC, PowerDrive, nuRom, UDMH, warpSpeed, PowerDiGi, brightnessFix, etc... Get it all here:http://www.PalmPowerups.com | |
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06-20-2009, 06:39 PM
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#56 | | Registered User
Join Date: May 2008 Location: Australia
Posts: 63
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Ok then! thanks for keeping us up to date Dmitry!
*fingers crossed that everything goes incredibly well and by some miracle DGOS is is able to port to the Treo Pro* | |
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06-23-2009, 01:56 PM
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#57 | | Dont Panic
Join Date: Sep 2005 Location: plymouth nc usa
Posts: 674
| well ive beenn waiting to hear somethin...keep up the good work and yeah im interested...
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06-25-2009, 07:21 PM
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#58 | | Registered User
Join Date: Apr 2005
Posts: 1,119
| Would it be possible to run applications from SD with DGOS in a better way than PalmOS does?
I mean:
1-run directly from SD with no copy in Ram
2-a structure of application in SD with directories for each app
3-possibility to add datas that are relationed with the app even they dont have the same CRID
Last edited by enotar : 06-25-2009 at 07:27 PM.
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06-25-2009, 07:50 PM
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#59 | | Software engineer/hacker
Join Date: Jan 2004 Location: Silicon Valley, CA
Posts: 5,061
| there is no concept of "CRID" in DGOS - it is a modern OS where apps are free to do with data whatever they please
running from card is how ALL apps run. RAM is only used for RAM purposes
__________________ Annoying me is NOT an approved way of encouraging me to produce software My software:PowerSDHC, PowerDrive, nuRom, UDMH, warpSpeed, PowerDiGi, brightnessFix, etc... Get it all here:http://www.PalmPowerups.com | |
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07-02-2009, 09:09 PM
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#60 | | Registered User
Join Date: Jun 2008 Location: USA
Posts: 22
| I'm interested. I have a Lifedrive, soon to be a lifeflash, once I get the parts. | |
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