[lkml]   [2004]   [Oct]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [RFC PATCH] scheduler: Dynamic sched_domains
On Wed, 2004-10-06 at 19:13, Nick Piggin wrote:
> This is what I did in my first (that nobody ever saw) implementation of
> sched domains. Ie. no sched_groups, just use sched_domains as the balancing
> object... I'm not sure this works too well.
> For example, your bottom level domain is going to basically be a redundant,
> single CPU on most topologies, isn't it?

I forgot to respond to this part in my last mail... :(

My benchmarks haven't shown any real deviation in performance from stock
-mm. Granted, my benchmarking has been very limited, pretty much just
running kernbench on a few different machines with different configs
(ie: SMT, SMP & NUMA on/off). A performance NOOP is exactly what I was
hoping for, though. I don't really expect these changes to be either a
performance win or loss, but a functionality improvement.

The patch is pretty dense because of all the renaming, but there are no
single CPU domains. The lowest level domain would be:

1) Node domains, for NUMA w/ SMP
2) Sibling domains, for SMT or NUMA w/ SMT
3) System domain, for flat SMP

The pseudo code version of my arch_init_sched_domains() looks like:

cpu_usable_map = cpu_online_map & ~cpu_isolated_map
create system domain;
create node domain, parented to system domain;
create sibling domain, parented to node domain;
attach sibling cpu to it's domain;
attach cpu to either its node domain or system domain;

So there shouldn't be any redundant CPU domains.


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2005-03-22 14:06    [W:0.255 / U:1.240 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site