[ruby-core:81035] Re: [ruby-cvs:65407] normal:r58236 (trunk): thread.c: comments on M:N threading [ci skip]

SASADA Koichi <[e-mail]> wrote:
> On 2017/05/08 12:01, Eric Wong wrote:
> >>> .
> >> `Fiber.scheduler.add_auto_fiber{ ... }` (naming is not fixed) (operation
> >> for scheduler) is my first idea.
> > Too verbose, I think.  If I want to type more, I would not be
> > using Ruby :)   How about adding kwarg to Fiber.new?
> 
> This design introduce new aspect: can we make schedulers per a thread?

Maybe; if we can avoid GVL and introduce more parallelism.

However, I think having one epoll/kqueue FD is better for a
whole process; maybe one epoll/kqueue per-core (not per-thread)
at maximum.

I can easily imagine Ruby doing 100 native threads in one process
(8 cores, 10-20 rotational disks, 2 SSD), but 20000-30000 fibers.


Side note: First, I would like to make fibers smaller.
Right now rb_fiber_t stores all of the rb_thread_t
struct, but not all fields get used.  I started to work on
splitting out to a new struct rb_thread_context_t earlier:

	https://80x24.org/spew/[e-mail]/raw
	(incomplete, I will work on it some more tomorrow)

The end goal is to avoid storing all of rb_thread_t inside
rb_context_t/rb_fiber_t; and only store rb_thread_context_t.
That should reduce memory overhead and maybe make switching
faster.

Also, I think we can use uint32_t (or even uint16_t * 4096)
to store stack sizes.  Using 64-bit size_t represent a
stack size is excessive.

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