Hi, v5 of a series of patches, originally authored by Mathieu, with the intent of fixing a long standing issue of SCHED_DEADLINE bandwidth accounting. As originally reported by Steve [1], when hotplug and/or (certain) cpuset reconfiguration operations take place, DEADLINE bandwidth accounting information is lost since root domains are destroyed and recreated. Mathieu's approach is based on restoring bandwidth accounting info on the newly created root domains by iterating through the (DEADLINE) tasks belonging to the configured cpuset(s). Main problem of v4 was caused by the trylocking of cpuset_mutex. As noticed by Steve [2], if multiple tasks are created at they same time only the first gets to grab the mutex, the other get -EBUSY and need to retry. Not really nice. So, in v5 I'm proposing to use callback_lock instead of cpuset_mutex, which AFAIU should be enough to grant read-only safe access to cpusets. 01/05 has been dropped because it wasn't really adding much and was only causing false positives. 05/05 is still too much DEADLINE specific I guess, but let's first agree on foundations patches. Set also available at https://github.com/jlelli/linux.git fixes/deadline/root-domain-accounting-v5 Thanks, - Juri [1] https://lkml.org/lkml/2016/2/3/966 [2] https://lore.kernel.org/lkml/20180614161142.69f186a6@xxxxxxxxxxxxxxxxxx/ Juri Lelli (1): cgroup/cpuset: make callback_lock raw Mathieu Poirier (4): sched/topology: Adding function partition_sched_domains_locked() sched/core: Streamlining calls to task_rq_unlock() sched/core: Prevent race condition between cpuset and __sched_setscheduler() cpuset: Rebuild root domain deadline accounting information include/linux/cpuset.h | 6 ++ include/linux/sched.h | 5 ++ include/linux/sched/deadline.h | 8 ++ include/linux/sched/topology.h | 10 +++ kernel/cgroup/cpuset.c | 147 +++++++++++++++++++++++++-------- kernel/sched/core.c | 34 +++++--- kernel/sched/deadline.c | 31 +++++++ kernel/sched/sched.h | 3 - kernel/sched/topology.c | 30 +++++-- 9 files changed, 222 insertions(+), 52 deletions(-) -- 2.17.1
