Date: Mon, 3 Feb 1997 09:47:05 +0900 (JST) From: Michael Hancock <michaelh@cet.co.jp> To: "David S. Miller" <davem@jenolan.rutgers.edu> Cc: netdev@roxanne.nuclecu.unam.mx, roque@di.fc.ul.pt, freebsd-smp@freebsd.org Subject: Re: SMP Message-ID: <Pine.SV4.3.95.970203093914.4624A-100000@parkplace.cet.co.jp> In-Reply-To: <199702021202.HAA09281@jenolan.caipgeneral>
next in thread | previous in thread | raw e-mail | index | archive | help
On Sun, 2 Feb 1997, David S. Miller wrote:
> I think some key subsystems would benefit from per processor pools
> (less contention) and the code can still be structured for short
> holds.
>
[..]
> On the other hand, I like the idea of:
>
> 1) per cpu pools for object FOO
>
> 2) global secondard pool for object class BAR which
> FOO is a member of
>
> and thus the strategy becomes:
>
> alloc_a_FOO()
> {
> again:
> if(FOO_free_list[smp_processor_id()]) {
> /* Go like smoke */
> } else {
> lock_global_pool();
> get_some_for_me();
> if(others_running_low)
> feed_them_too();
> unlock_global_pool();
> goto again;
> }
> }
>
> free_a_FOO()
> {
> if(my_pool_only_moderately_full) {
> give_it_to_me();
> } else {
> feed_someone_else_who_needs_it();
> }
> }
>
> The idea is that when you need to enter a contension situation, you
> make the most of it by working towards keeping others from running
> into the same situation.
>
> Another modification to the idea on the freeing side is to always free
> this FOO to the local per-cpu queue, and if other cpus could starve
> soon you give some of your oldest FOO's to them, the encourage cache
> locality.
>
> Just some ideas. These are some of ideas I was toying about with
> Larry McVoy when we were discussing with each other how N processors
> could go full throttle on an N high speed interface machine with near
> zero contention.
I like it a lot. You can use a simple policy mechanism such as high and
low watermarks for resource balancing.
Terry has talked about using a global pool for resource balancing on this
list, but it's nice to see in something C like.
Regards,
Mike Hancock
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?Pine.SV4.3.95.970203093914.4624A-100000>