Messages in this thread | | | From | Waiman Long <> | Subject | [PATCH v10 0/5] sched: Persistent user requested affinity | Date | Thu, 22 Sep 2022 14:00:36 -0400 |
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v10: - Squash patches 4, 5 & 6 together into a single patch as suggested by PeterZ.
v9: - Fix non-SMP config build errors in patch 4 reported by kernel test robot. - Disable user_cpus_ptr masking also when any of the SCA_MIGRATE_* flags are set.
v8: - Add patches "sched: Introduce affinity_context structure" and "sched: Always clear user_cpus_ptr in do_set_cpus_allowed()" as suggested by PeterZ. - Better handle cpuset and sched_setaffinity() race in patch 5.
v7: - Make changes recommended by Peter such as making scratch_mask allocation earlier and using percpu variable to pass information.
The user_cpus_ptr field is added by commit b90ca8badbd1 ("sched: Introduce task_struct::user_cpus_ptr to track requested affinity") which uses it narrowly to allow keeping cpus affinity intact with asymmetric cpu setup.
This patchset extends user_cpus_ptr to store user requested cpus affinity via the sched_setaffinity() API. With that information available, it will enable cpuset and other callers of set_cpus_allowed_ptr() like hotplug to keep cpus afinity as close to what the user wants as possible within the cpu list constraint of the current cpuset. Otherwise some change to the cpuset hierarchy or a hotplug event may reset the cpumask of the tasks in the affected cpusets to the default cpuset value even if those tasks have cpus affinity explicitly set by the users before.
It also means that once sched_setaffinity() is called successfully, user_cpus_ptr will remain allocated until the task exits except in some rare circumstances.
Waiman Long (5): sched: Add __releases annotations to affine_move_task() sched: Use user_cpus_ptr for saving user provided cpumask in sched_setaffinity() sched: Enforce user requested affinity sched: Handle set_cpus_allowed_ptr(), sched_setaffinity() & other races sched: Always clear user_cpus_ptr in do_set_cpus_allowed()
kernel/sched/core.c | 231 +++++++++++++++++++++++++--------------- kernel/sched/deadline.c | 7 +- kernel/sched/sched.h | 22 +++- 3 files changed, 169 insertions(+), 91 deletions(-)
-- 2.31.1
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