Messages in this thread Patch in this message | | | Date | Thu, 06 Nov 2008 09:45:16 +0800 | From | Li Zefan <> | Subject | [PATCH] sched: fix a bug in sched domain degenerate |
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(1) on i386 with SCHED_SMT and SCHED_MC enabled # mount -t cgroup -o cpuset xxx /mnt # echo 0 > /mnt/cpuset.sched_load_balance # mkdir /mnt/0 # echo 0 > /mnt/0/cpuset.cpus # dmesg CPU0 attaching sched-domain: domain 0: span 0 level CPU groups: 0
(2) on i386 with SCHED_MC enabled but SCHED_SMT disabled # same with (1) # dmesg CPU0 attaching NULL sched-domain.
The bug is some sched domains may be skipped unintentionally when doing sched domain degenerating.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> --- kernel/sched.c | 6 ++++-- 1 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/kernel/sched.c b/kernel/sched.c index dee79ad..b13f45a 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -6875,15 +6875,17 @@ cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu) struct sched_domain *tmp; /* Remove the sched domains which do not contribute to scheduling. */ - for (tmp = sd; tmp; tmp = tmp->parent) { + for (tmp = sd; tmp; ) { struct sched_domain *parent = tmp->parent; if (!parent) break; + if (sd_parent_degenerate(tmp, parent)) { tmp->parent = parent->parent; if (parent->parent) parent->parent->child = tmp; - } + } else + tmp = tmp->parent; } if (sd && sd_degenerate(sd)) { -- 1.5.4.rc3
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