Re: [RFC] sched: implement the exclusive wait queue as a LIFO queue

[David Howells]

Changli Gao <xiaosuo@xxxxxxxxx> wrote:

> I don't know how to do that, as maybe there are non-exclusive and
> exclusive wait queues in the same wait queue head. If we want to
> enqueue exclusive wait queues at the head of exclusive queues, we have
> to know where the head is, otherwise, we have to loop to find the head
> when enqueuing.

I suspect you really want to have the semantics defined per-queue.  _Either_ a
queue is FIFO (such as processes waiting for a resource so they can do
something with it) _or_ it is LIFO (such as a pool of processes waiting to be
given work).

How often do the two actually mix?  And if they do, is that really an error?

David
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