Re: thread ids, task ids and subsystems

[Michal 'hramrach' Suchanek]

On Thu, Apr 03, 2003 at 12:39:48PM +0200, Niels Möller wrote:
> Marcus Brinkmann <address@hidden> writes:

>   * Get and set (some) resource limits, like cpu time and amount of
>     memory. Limits apply per accounting id. Things like the "number of
>     open files" are unknown to the task server. It's not clear to me
>     at all which server should enforce limits on the number of open
>     files. It doesn't fit well with the delegated filesystem of the
>     Hurd.
To get quotas for a quota server could be introduced. An example for files
handles:
 - a task may register with a quota server, and the quota server gives it
        some amounts of different resources
 - whenever a task contacts a server (such as fs server) the server could
        demand some amount of resources registered at a specified quota server
 - if the task is registered with that quota server and has enough resources it
        can pass the requested amount to the server (other task)
 - when the request is completed (ie file closed) the server should relinquish
        the resources obtained from the requesting task
 - at any time the requesting task may reclaim its resources it gave to the 
        server. The server may stop processing the requst but the mechanism
        must ensure the resources are returned in a short time (how short?)
 
The quota servers can implement any resource policies one can think of.
ie.     - obtain resources from another trusted quota server
        - associate user-specific (shared for all tasks of the same user)
                limit with a task at login-time, inherit limit form patent
                task to child tasks and allow suballocation of resources for
                child tasks
        - give any resources to any task

Especially the suballocation is interesting since I can think of two types:
        - "hard" - give some resources to the child, parent cannot use
                those resources while they are allocated for the child
        - "soft" - the child is limited by a quota specififed for it and
                the sum parent's and all childs' resources is limited by the
                quota of the parent, the sum of the suballocations made may
                exceed the parent quota
> 
>   * Get resource usage, for an individual task, or all tasks with a
>     given accounting id.
>