https://lkml.iu.edu/hypermail/linux/kernel/0209.2/1153.html

Re: 100,000 threads? [was: [ANNOUNCE] Native POSIX Thread Library
0.1]

From: Ingo Molnar (mingo@elte.hu)
Date: Fri Sep 20 2002 - 02:52:39 EST

  * Next message: Miles Lane: "Re: Dont understand hdc=ide-scsi
    behaviour."
  * Previous message: Vojtech Pavlik: "Re: compile error in pre7-ac2:
    usb & input"
  * In reply to: Rik van Riel: "Re: [ANNOUNCE] Native POSIX Thread
    Library 0.1"
  * Next in thread: Bill Davidsen: "Re: 100,000 threads? [was:
    [ANNOUNCE] Native POSIX Thread Library 0.1]"
  * Reply: Bill Davidsen: "Re: 100,000 threads? [was: [ANNOUNCE]
    Native POSIX Thread Library 0.1]"
  * Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

---------------------------------------------------------------------

On Thu, 19 Sep 2002, Rik van Riel wrote:

> So, where did you put those 800 MB of kernel stacks needed for
100,000
> threads ?

With the default split and kernel stack we can start up 94,000
threads on
x86. With Ben's/Dave's patch we can have up to 188,000 threads. With
a 2:2
GB VM split configured we can start 376,000 threads. If someone's
that
desperate then with a 1:3 split we can start up 564,000 threads.

Anton tested 1 million concurrent threads on one of his bigger
PowerPC
boxes, which started up in around 30 seconds. I think he saw a load
average of around 200 thousand. [ie. the runqueue was probably a few
hundred thousand entries long at times.]

> If you used the standard 3:1 user/kernel split you'd be using all
of
> ZONE_NORMAL for kernel stacks, but if you use a 2:2 split you'll
end up
> with a lot less user space (bad if you want to have many threads in
the
> same address space).

the extreme high-end of threading typically uses very controlled
applications and very small user level stacks.

as to the question of why so many threads, the answer is because we
can :)
This, besides demonstrating some of the recent scalability advances,
gives
us the warm fuzzy feeling that things are right in this area. I mean,
there are architectures where Linux could map a petabyte of RAM just
fine,
even though that might not be something we desperately need today.

        Ingo

-
To unsubscribe from this list: send the line "unsubscribe
linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

---------------------------------------------------------------------

  * Next message: Miles Lane: "Re: Dont understand hdc=ide-scsi
    behaviour."
  * Previous message: Vojtech Pavlik: "Re: compile error in pre7-ac2:
    usb & input"
  * In reply to: Rik van Riel: "Re: [ANNOUNCE] Native POSIX Thread
    Library 0.1"
  * Next in thread: Bill Davidsen: "Re: 100,000 threads? [was:
    [ANNOUNCE] Native POSIX Thread Library 0.1]"
  * Reply: Bill Davidsen: "Re: 100,000 threads? [was: [ANNOUNCE]
    Native POSIX Thread Library 0.1]"
  * Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

---------------------------------------------------------------------

This archive was generated by hypermail 2b29 : Mon Sep 23 2002 -
22:00:29 EST