Messages in this thread | | | From | Vincent Guittot <> | Date | Thu, 28 Mar 2024 15:43:01 +0100 | Subject | Re: [PATCH 1/1] sched/fair: allow disabling newidle_balance with sched_relax_domain_level |
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On Thu, 28 Mar 2024 at 01:31, Vitalii Bursov <vitaly@bursov.com> wrote: > > Change relax_domain_level checks so that it would be possible > to exclude all domains from newidle balancing. > > This matches the behavior described in the documentation: > -1 no request. use system default or follow request of others. > 0 no search. > 1 search siblings (hyperthreads in a core). > > "2" enables levels 0 and 1, level_max excludes the last (level_max) > level, and level_max+1 includes all levels.
I was about to say that max+1 is useless because it's the same as -1 but it's not exactly the same because it can supersede the system wide default_relax_domain_level. I wonder if one should be able to enable more levels than what the system has set by default.
> > Signed-off-by: Vitalii Bursov <vitaly@bursov.com> > --- > kernel/cgroup/cpuset.c | 2 +- > kernel/sched/debug.c | 1 + > kernel/sched/topology.c | 2 +- > 3 files changed, 3 insertions(+), 2 deletions(-) > > diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c > index 4237c874871..da24187c4e0 100644 > --- a/kernel/cgroup/cpuset.c > +++ b/kernel/cgroup/cpuset.c > @@ -2948,7 +2948,7 @@ bool current_cpuset_is_being_rebound(void) > static int update_relax_domain_level(struct cpuset *cs, s64 val) > { > #ifdef CONFIG_SMP > - if (val < -1 || val >= sched_domain_level_max) > + if (val < -1 || val > sched_domain_level_max + 1) > return -EINVAL; > #endif > > diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c > index 8d5d98a5834..8454cd4e5e1 100644 > --- a/kernel/sched/debug.c > +++ b/kernel/sched/debug.c > @@ -423,6 +423,7 @@ static void register_sd(struct sched_domain *sd, struct dentry *parent) > > #undef SDM > > + debugfs_create_u32("level", 0444, parent, (u32 *)&sd->level);
IMO, this should be a separate patch as it's not part of the fix
> debugfs_create_file("flags", 0444, parent, &sd->flags, &sd_flags_fops); > debugfs_create_file("groups_flags", 0444, parent, &sd->groups->flags, &sd_flags_fops); > } > diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c > index 99ea5986038..3127c9b30af 100644 > --- a/kernel/sched/topology.c > +++ b/kernel/sched/topology.c > @@ -1468,7 +1468,7 @@ static void set_domain_attribute(struct sched_domain *sd, > } else > request = attr->relax_domain_level; > > - if (sd->level > request) { > + if (sd->level >= request) {
good catch and worth : Fixes: 9ae7ab20b483 ("sched/topology: Don't set SD_BALANCE_WAKE on cpuset domain relax")
> /* Turn off idle balance on this domain: */ > sd->flags &= ~(SD_BALANCE_WAKE|SD_BALANCE_NEWIDLE); > } > -- > 2.20.1 >
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