From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Low Subject: [RFC][PATCH] cpuset, sched: Fix cpuset sched_relax_domain_level Date: Wed, 28 Jan 2015 12:47:05 -0800 Message-ID: <1422478025.4111.31.camel@j-VirtualBox> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: Sender: linux-kernel-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" To: Tejun Heo , Li Zefan , Peter Zijlstra Cc: linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, aswin@hp.com, scott.norton@hp.com, chegu_vinod@hp.com, Jason Low The cpuset.sched_relax_domain_level can control how far we do immediate load balancing on a system. However, it was found on recent kernels that echo'ing a value into cpuset.sched_relax_domain_level did not reduce any immediate load balancing. The reason this occurred was because the update_domain_attr_tree() traversal did not update for the "top_cpuset". This resulted in nothing being changed when modifying the sched_relax_domain_level parameter. This patch was able to address that problem by having update_domain_attr_tree() allowing updates for the root (top_cpuset) in the cpuset traversal. Signed-off-by: Jason Low --- kernel/cpuset.c | 12 +++++++----- 1 files changed, 7 insertions(+), 5 deletions(-) diff --git a/kernel/cpuset.c b/kernel/cpuset.c index 64b257f..0f58c54 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -541,15 +541,17 @@ update_domain_attr(struct sched_domain_attr *dattr, struct cpuset *c) } static void update_domain_attr_tree(struct sched_domain_attr *dattr, - struct cpuset *root_cs) + struct cpuset *root_cs, bool update_root) { struct cpuset *cp; struct cgroup_subsys_state *pos_css; rcu_read_lock(); cpuset_for_each_descendant_pre(cp, pos_css, root_cs) { - if (cp == root_cs) - continue; + if (cp == root_cs) { + if (!update_root) + continue; + } /* skip the whole subtree if @cp doesn't have any CPU */ if (cpumask_empty(cp->cpus_allowed)) { @@ -644,7 +646,7 @@ static int generate_sched_domains(cpumask_var_t **domains, dattr = kmalloc(sizeof(struct sched_domain_attr), GFP_KERNEL); if (dattr) { *dattr = SD_ATTR_INIT; - update_domain_attr_tree(dattr, &top_cpuset); + update_domain_attr_tree(dattr, &top_cpuset, true); } cpumask_copy(doms[0], top_cpuset.effective_cpus); @@ -752,7 +754,7 @@ restart: if (apn == b->pn) { cpumask_or(dp, dp, b->effective_cpus); if (dattr) - update_domain_attr_tree(dattr + nslot, b); + update_domain_attr_tree(dattr + nslot, b, false); /* Done with this partition */ b->pn = -1; -- 1.7.1