lkml.org 
[lkml]   [2012]   [Jun]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: 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.


    \
     
     \ /
      Last update: 2012-06-05 21:01    [W:0.025 / U:62.464 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site