Messages in this thread | | | Date | Tue, 5 Jun 2012 13:34:39 -0500 | From | Dimitri Sivanich <> | Subject | Re: relax_domain_level boot parameter has no effect |
| |
On Mon, Jun 04, 2012 at 01:16:14PM -0500, Dimitri Sivanich wrote: > On Mon, Jun 04, 2012 at 05:37:42PM +0200, Peter Zijlstra wrote: > > On Fri, 2012-06-01 at 16:03 -0500, Dimitri Sivanich wrote: > > > I noticed (and verified) that the relax_domain_level boot parameter does not > > > get processed because sched_domain_level_max is 0 at the time that > > > setup_relax_domain_level() is run. > > > > > > int sched_domain_level_max; > > > > > > static int __init setup_relax_domain_level(char *str) > > > { > > > unsigned long val; > > > > > > val = simple_strtoul(str, NULL, 0); > > > if (val < sched_domain_level_max) > > > default_relax_domain_level = val; > > > > > > return 1; > > > } > > > __setup("relax_domain_level=", setup_relax_domain_level); > > > > Ah indeed.. this has been so for a while I guess. > > On a very related note, the sched_relax_domain_level setting in cpuset > doesn't appear to work correctly either (if I'm interpreting all of this > correctly). > > The reason is that the build_sched_domain() routine calls the > set_domain_attribute() routine prior to setting the sd->level, however, > the set_domain_attribute() routine relies on the sd->level to decide whether > idle load balancing will be off/on. > > static void set_domain_attribute(struct sched_domain *sd, > .. > ==> if (request < sd->level) { > /* turn off idle balance on this domain */ > .. > .. > struct sched_domain *build_sched_domain(struct sched_domain_topology_level *tl, > .. > ==> set_domain_attribute(sd, attr); > cpumask_and(sched_domain_span(sd), cpu_map, tl->mask(cpu)); > if (child) { > ==> sd->level = child->level + 1; > sched_domain_level_max = max(sched_domain_level_max, sd->level); > > > > What are you using this knob for? > > I was poking around for different ways to turn off idle load balancing when > I ran into all of this.
I'll submit a patch shortly that should return these back to what appears to be their intended functionality.
| |