Comments on the KSE option

[David Xu]

On Sunday 29 October 2006 03:41, Paul Allen wrote:
> Let us suppose that this M:N business is important, perhaps something
> to consider is why and whether the kernel has so much knowledge of it.
>
> If I read Matt Dillon's comment closely enough, I believe his precise
> recommendation was not "something like kse as Julian read it" but
> rather something where this M:N component was entirely part of the
> userland threading support and therefore would just go away or not
> depending on which library you linked with.
>
> I think posix might require a global priority space though...
>

Yes, I think if libpthread wants to implement POSIX priority mutex and 
SCHED_FIFO, SCHED_RR for system scope thread, it should work out a
way to unify priority for all process scope and system scope threads, 
it has to support it if we want to implement process-shared mutex,  
current we can not but other OS can, I found  Solaris's M:N implementation
will bind a M:N thread on a LWP once it has owned a PRIO_INHERIT or
PRIO_PROTECT mutex and raise the LWP's priority, fix me if I am wrong.
Solaris now favors 1:1.

> Anyways it remains dubious in my mind that the kernel should allow
> a user to create many processes but penalize creating threads.
>
> The only reason I can think of is that you expect people to be sloppy
> with their threads and careful with their processes.
>
> Still if I am ray-tracing why should I need to make a point of picking
> my thread/process balance to get around your mechanism.  If fairness
> is the goal why am I even allowed to do so?