Talk:Daemon - Revision history

Jnc: /* Kernel X's */ new section

2023-12-15T16:05:40Z

‎Kernel X's: new section

Jnc: Whose job it is to write dirty process memory pages to disk, then?

2023-08-17T13:43:15Z

Whose job it is to write dirty process memory pages to disk, then?

Larsbrinkhoff: /* Demon, dragon, phantom */ SYSDOC;USR > answers most questions.

2023-08-17T12:53:36Z

‎Demon, dragon, phantom: SYSDOC;USR > answers most questions.

Jnc: /* Demon, dragon, phantom */ A natural task for the CORE job

2023-08-16T11:48:39Z

‎Demon, dragon, phantom: A natural task for the CORE job

Larsbrinkhoff: /* Demon, dragon, phantom */ I'll try to check what the CORE job does.

2023-08-16T06:11:57Z

‎Demon, dragon, phantom: I'll try to check what the CORE job does.

Jnc: /* Demon, dragon, phantom */ A useful info-gathering project

2023-08-15T16:44:49Z

‎Demon, dragon, phantom: A useful info-gathering project

Larsbrinkhoff: /* Demon, dragon, phantom */ MVS: "started tasks" or "subsystems"?

2023-08-15T15:33:40Z

‎Demon, dragon, phantom: MVS: "started tasks" or "subsystems"?

Larsbrinkhoff: /* Demon, dragon, phantom */ Better description of a VMS symbiont.

2023-08-15T09:45:09Z

‎Demon, dragon, phantom: Better description of a VMS symbiont.

Larsbrinkhoff: Symbiont?

2023-08-15T09:36:41Z

Symbiont?

Larsbrinkhoff: /* Demon, dragon, phantom / Coff* coff yes.

2023-08-15T05:40:30Z

‎Demon, dragon, phantom: *Coff* *coff* yes.

← Older revision		Revision as of 16:05, 15 December 2023
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	::: I note that SYSDOC;USR > says that both the SYS and CORE jobs run in Exec mode - which makes sense, they can use the Exec page tables - so, between that, and the code being built into the system, I think they both qualify as what I've been calling 'system processes' (I'll get to COFF about that soon, I promise :-); definitely not ordinary daemons!		::: I note that SYSDOC;USR > says that both the SYS and CORE jobs run in Exec mode - which makes sense, they can use the Exec page tables - so, between that, and the code being built into the system, I think they both qualify as what I've been calling 'system processes' (I'll get to COFF about that soon, I promise :-); definitely not ordinary daemons!
	::: Good find on that SYSDOC file, I'll add it to the article. [[User:Jnc\|Jnc]] ([[User talk:Jnc\|talk]]) 15:43, 17 August 2023 (CEST)		::: Good find on that SYSDOC file, I'll add it to the article. [[User:Jnc\|Jnc]] ([[User talk:Jnc\|talk]]) 15:43, 17 August 2023 (CEST)
		+
		+	== Kernel X's ==
		+
		+	It sounds like 'kernel X' (where 'X' is the abstraction provided by the OS in question) is the preferred term for abstractions that do system functions; 'kernel thread' would be the preferred term in OS's which have threads. I'm going to go with 'kernel process' as the article name, because in the first systems that used these things, they provided processes. So, I'll crank out the [[kernel process]] article at some point, and cover kernel threads there. [[User:Jnc\|Jnc]] ([[User talk:Jnc\|talk]]) 17:05, 15 December 2023 (CET)

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 ::: Nothing too thrilling from IBM land so far: ''"On MVS, they are called "started tasks". There could also be some overlap with what MVS calls "subsystems".'' [[User:Larsbrinkhoff|Larsbrinkhoff]] ([[User talk:Larsbrinkhoff|talk]]) 17:33, 15 August 2023 (CEST)
-:::: I've been too busy with a huge project Ulli started, to organize the DEC disks, to do anything with this. Soon! If you're up for it, it might be use to look at the ITS core job and see exactly what it does. My hypothesis that it writes out 'dirty' pages is just a guess. [[User:Jnc|Jnc]] ([[User talk:Jnc|talk]]) 18:44, 15 August 2023 (CEST)
+I've been too busy with a huge project Ulli started, to organize the DEC disks, to do anything with this. Soon! If you're up for it, it might be useful to look at the ITS core job and see exactly what it does. My hypothesis that it writes out 'dirty' pages is just a guess. [[User:Jnc|Jnc]] ([[User talk:Jnc|talk]]) 18:44, 15 August 2023 (CEST)
-::::: Good idea, I'll try to do that.  What we need is a ''Hacks and Implementation of the ITS Operating System'' with a cute dragon mascot. [[User:Larsbrinkhoff|Larsbrinkhoff]] ([[User talk:Larsbrinkhoff|talk]]) 08:11, 16 August 2023 (CEST)
+Good idea, I'll try to do that.  What we need is a ''Hacks and Implementation of the ITS Operating System'' with a cute dragon mascot. [[User:Larsbrinkhoff|Larsbrinkhoff]] ([[User talk:Larsbrinkhoff|talk]]) 08:11, 16 August 2023 (CEST)
-::::: I looked at ''ITS 1.5 Reference Manual'', and at one point (see "4.3 The Core Allocator"), it had the work of 'shuffling' processes around in memory ('the big BLT') to coalesce free space (life before paging :-), and making room for someone who needed a block. So, much like the UNIX 'swapping' process. If ITS used a process to write out 'dirty' pages (unlike Multics), it seems that the CORE job would have been the natural place to do it. [[User:Jnc|Jnc]] ([[User talk:Jnc|talk]]) 13:48, 16 August 2023 (CEST)
+: I looked at ''ITS 1.5 Reference Manual'', and at one point (see "4.3 The Core Allocator"), it had the work of 'shuffling' processes around in memory ('the big BLT') to coalesce free space (life before paging :-), and making room for someone who needed a block. So, much like the UNIX 'swapping' process. If ITS used a process to write out 'dirty' pages (unlike Multics), it seems that the CORE job would have been the natural place to do it. [[User:Jnc|Jnc]] ([[User talk:Jnc|talk]]) 13:48, 16 August 2023 (CEST)
-:::::: I found both SYS and CORE is pretty well explained in [https://github.com/PDP-10/its/blob/master/doc/sysdoc/usr.102#L664 SYSDOC;USR >]  Checking the code in SYSTEM; CORE >, I see once instance of writing dirty pages to disk, but not much more.  Shuffling is still being done to maintain continuous physical memory regions. [[User:Larsbrinkhoff|Larsbrinkhoff]] ([[User talk:Larsbrinkhoff|talk]]) 14:53, 17 August 2023 (CEST)
+:: I found both SYS and CORE is pretty well explained in [https://github.com/PDP-10/its/blob/master/doc/sysdoc/usr.102#L664 SYSDOC;USR >]  Checking the code in SYSTEM; CORE >, I see once instance of writing dirty pages to disk, but not much more.  Shuffling is still being done to maintain continuous physical memory regions. [[User:Larsbrinkhoff|Larsbrinkhoff]] ([[User talk:Larsbrinkhoff|talk]]) 14:53, 17 August 2023 (CEST)

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	::::: I looked at ''ITS 1.5 Reference Manual'', and at one point (see "4.3 The Core Allocator"), it had the work of 'shuffling' processes around in memory ('the big BLT') to coalesce free space (life before paging :-), and making room for someone who needed a block. So, much like the UNIX 'swapping' process. If ITS used a process to write out 'dirty' pages (unlike Multics), it seems that the CORE job would have been the natural place to do it. [[User:Jnc\|Jnc]] ([[User talk:Jnc\|talk]]) 13:48, 16 August 2023 (CEST)		::::: I looked at ''ITS 1.5 Reference Manual'', and at one point (see "4.3 The Core Allocator"), it had the work of 'shuffling' processes around in memory ('the big BLT') to coalesce free space (life before paging :-), and making room for someone who needed a block. So, much like the UNIX 'swapping' process. If ITS used a process to write out 'dirty' pages (unlike Multics), it seems that the CORE job would have been the natural place to do it. [[User:Jnc\|Jnc]] ([[User talk:Jnc\|talk]]) 13:48, 16 August 2023 (CEST)
		+
		+	:::::: I found both SYS and CORE is pretty well explained in [https://github.com/PDP-10/its/blob/master/doc/sysdoc/usr.102#L664 SYSDOC;USR >] Checking the code in SYSTEM; CORE >, I see once instance of writing dirty pages to disk, but not much more. Shuffling is still being done to maintain continuous physical memory regions. [[User:Larsbrinkhoff\|Larsbrinkhoff]] ([[User talk:Larsbrinkhoff\|talk]]) 14:53, 17 August 2023 (CEST)

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	::::: Good idea, I'll try to do that. What we need is a ''Hacks and Implementation of the ITS Operating System'' with a cute dragon mascot. [[User:Larsbrinkhoff\|Larsbrinkhoff]] ([[User talk:Larsbrinkhoff\|talk]]) 08:11, 16 August 2023 (CEST)		::::: Good idea, I'll try to do that. What we need is a ''Hacks and Implementation of the ITS Operating System'' with a cute dragon mascot. [[User:Larsbrinkhoff\|Larsbrinkhoff]] ([[User talk:Larsbrinkhoff\|talk]]) 08:11, 16 August 2023 (CEST)
		+
		+	::::: I looked at ''ITS 1.5 Reference Manual'', and at one point (see "4.3 The Core Allocator"), it had the work of 'shuffling' processes around in memory ('the big BLT') to coalesce free space (life before paging :-), and making room for someone who needed a block. So, much like the UNIX 'swapping' process. If ITS used a process to write out 'dirty' pages (unlike Multics), it seems that the CORE job would have been the natural place to do it. [[User:Jnc\|Jnc]] ([[User talk:Jnc\|talk]]) 13:48, 16 August 2023 (CEST)

← Older revision		Revision as of 06:11, 16 August 2023
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	:::: I've been too busy with a huge project Ulli started, to organize the DEC disks, to do anything with this. Soon! If you're up for it, it might be use to look at the ITS core job and see exactly what it does. My hypothesis that it writes out 'dirty' pages is just a guess. [[User:Jnc\|Jnc]] ([[User talk:Jnc\|talk]]) 18:44, 15 August 2023 (CEST)		:::: I've been too busy with a huge project Ulli started, to organize the DEC disks, to do anything with this. Soon! If you're up for it, it might be use to look at the ITS core job and see exactly what it does. My hypothesis that it writes out 'dirty' pages is just a guess. [[User:Jnc\|Jnc]] ([[User talk:Jnc\|talk]]) 18:44, 15 August 2023 (CEST)
		+
		+	::::: Good idea, I'll try to do that. What we need is a ''Hacks and Implementation of the ITS Operating System'' with a cute dragon mascot. [[User:Larsbrinkhoff\|Larsbrinkhoff]] ([[User talk:Larsbrinkhoff\|talk]]) 08:11, 16 August 2023 (CEST)

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	::: Nothing too thrilling from IBM land so far: ''"On MVS, they are called "started tasks". There could also be some overlap with what MVS calls "subsystems".'' [[User:Larsbrinkhoff\|Larsbrinkhoff]] ([[User talk:Larsbrinkhoff\|talk]]) 17:33, 15 August 2023 (CEST)		::: Nothing too thrilling from IBM land so far: ''"On MVS, they are called "started tasks". There could also be some overlap with what MVS calls "subsystems".'' [[User:Larsbrinkhoff\|Larsbrinkhoff]] ([[User talk:Larsbrinkhoff\|talk]]) 17:33, 15 August 2023 (CEST)
		+
		+	:::: I've been too busy with a huge project Ulli started, to organize the DEC disks, to do anything with this. Soon! If you're up for it, it might be use to look at the ITS core job and see exactly what it does. My hypothesis that it writes out 'dirty' pages is just a guess. [[User:Jnc\|Jnc]] ([[User talk:Jnc\|talk]]) 18:44, 15 August 2023 (CEST)

← Older revision		Revision as of 15:33, 15 August 2023
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	::: Here's one, maybe: https://wiki.vmssoftware.com/Symbiont [[User:Larsbrinkhoff\|Larsbrinkhoff]] ([[User talk:Larsbrinkhoff\|talk]]) 11:36, 15 August 2023 (CEST)		::: Here's one, maybe: https://wiki.vmssoftware.com/Symbiont [[User:Larsbrinkhoff\|Larsbrinkhoff]] ([[User talk:Larsbrinkhoff\|talk]]) 11:36, 15 August 2023 (CEST)
	::: ''Under VMS V4 and later, symbionts operate in a rather strange environment. A symbiont is a detached process (unlike VMS V3, where it was a subprocess of the job controller). However, it lacks several useful things that most processes have: symbionts have no CLI, which means that they can't spawn commands; symbionts are always created with username SYSTEM and one privilege (SETPRV); and symbionts cannot access process-permanent logicals (SYS$INPUT, SYS$OUTPUT, SYS$ERROR) the way other processes can.'' https://www.digiater.nl/openvms/freeware/v80/execsymb/freeware_readme.txt [[User:Larsbrinkhoff\|Larsbrinkhoff]] ([[User talk:Larsbrinkhoff\|talk]]) 11:44, 15 August 2023 (CEST)		::: ''Under VMS V4 and later, symbionts operate in a rather strange environment. A symbiont is a detached process (unlike VMS V3, where it was a subprocess of the job controller). However, it lacks several useful things that most processes have: symbionts have no CLI, which means that they can't spawn commands; symbionts are always created with username SYSTEM and one privilege (SETPRV); and symbionts cannot access process-permanent logicals (SYS$INPUT, SYS$OUTPUT, SYS$ERROR) the way other processes can.'' https://www.digiater.nl/openvms/freeware/v80/execsymb/freeware_readme.txt [[User:Larsbrinkhoff\|Larsbrinkhoff]] ([[User talk:Larsbrinkhoff\|talk]]) 11:44, 15 August 2023 (CEST)
		+
		+	::: Nothing too thrilling from IBM land so far: ''"On MVS, they are called "started tasks". There could also be some overlap with what MVS calls "subsystems".'' [[User:Larsbrinkhoff\|Larsbrinkhoff]] ([[User talk:Larsbrinkhoff\|talk]]) 17:33, 15 August 2023 (CEST)

← Older revision		Revision as of 09:45, 15 August 2023
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	::: Here's one, maybe: https://wiki.vmssoftware.com/Symbiont [[User:Larsbrinkhoff\|Larsbrinkhoff]] ([[User talk:Larsbrinkhoff\|talk]]) 11:36, 15 August 2023 (CEST)		::: Here's one, maybe: https://wiki.vmssoftware.com/Symbiont [[User:Larsbrinkhoff\|Larsbrinkhoff]] ([[User talk:Larsbrinkhoff\|talk]]) 11:36, 15 August 2023 (CEST)
		+	::: ''Under VMS V4 and later, symbionts operate in a rather strange environment. A symbiont is a detached process (unlike VMS V3, where it was a subprocess of the job controller). However, it lacks several useful things that most processes have: symbionts have no CLI, which means that they can't spawn commands; symbionts are always created with username SYSTEM and one privilege (SETPRV); and symbionts cannot access process-permanent logicals (SYS$INPUT, SYS$OUTPUT, SYS$ERROR) the way other processes can.'' https://www.digiater.nl/openvms/freeware/v80/execsymb/freeware_readme.txt [[User:Larsbrinkhoff\|Larsbrinkhoff]] ([[User talk:Larsbrinkhoff\|talk]]) 11:44, 15 August 2023 (CEST)

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	::: Please do! I usually find the discussions interesting, even though they inevitably derail into assorted ramblings.		::: Please do! I usually find the discussions interesting, even though they inevitably derail into assorted ramblings.
	::: Also, we have only covered two somewhat narrow environments: Unix and PDP-10. E.g. IBM people most have a plethora of terms for things like these, and then there are many smaller communities. I'll bring it up in some fora and see what falls out. [[User:Larsbrinkhoff\|Larsbrinkhoff]] ([[User talk:Larsbrinkhoff\|talk]]) 07:40, 15 August 2023 (CEST)		::: Also, we have only covered two somewhat narrow environments: Unix and PDP-10. E.g. IBM people most have a plethora of terms for things like these, and then there are many smaller communities. I'll bring it up in some fora and see what falls out. [[User:Larsbrinkhoff\|Larsbrinkhoff]] ([[User talk:Larsbrinkhoff\|talk]]) 07:40, 15 August 2023 (CEST)
		+
		+	::: Here's one, maybe: https://wiki.vmssoftware.com/Symbiont [[User:Larsbrinkhoff\|Larsbrinkhoff]] ([[User talk:Larsbrinkhoff\|talk]]) 11:36, 15 August 2023 (CEST)

← Older revision		Revision as of 05:40, 15 August 2023
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	:: "During system initialization, just before the ''init'' process is created, the bootstrapping code creates process 2 which is known as the ''pageout daemon''. It is this process that .. writ[es] back modified pages. The process leaves its normal dormant state upon being waken up due to the memory free list size dropping below an upper threshold."		:: "During system initialization, just before the ''init'' process is created, the bootstrapping code creates process 2 which is known as the ''pageout daemon''. It is this process that .. writ[es] back modified pages. The process leaves its normal dormant state upon being waken up due to the memory free list size dropping below an upper threshold."
	:: I wish there was a generally-accepted term for such processes. Maybe I'll ask on COFF? [[User:Jnc\|Jnc]] ([[User talk:Jnc\|talk]]) 18:15, 14 August 2023 (CEST)		:: I wish there was a generally-accepted term for such processes. Maybe I'll ask on COFF? [[User:Jnc\|Jnc]] ([[User talk:Jnc\|talk]]) 18:15, 14 August 2023 (CEST)
		+
		+	::: Please do! I usually find the discussions interesting, even though they inevitably derail into assorted ramblings.
		+	::: Also, we have only covered two somewhat narrow environments: Unix and PDP-10. E.g. IBM people most have a plethora of terms for things like these, and then there are many smaller communities. I'll bring it up in some fora and see what falls out. [[User:Larsbrinkhoff\|Larsbrinkhoff]] ([[User talk:Larsbrinkhoff\|talk]]) 07:40, 15 August 2023 (CEST)