# Introduce Add PR_NUMA_BALANCING in prctl. A large number of page faults will cause performance loss when numa balancing is performing. Thus those processes which care about worst-case performance need numa balancing disabled. Others, on the contrary, allow a temporary performance loss in exchange for higher average performance, so enable numa balancing is better for them. Numa balancing can only be controlled globally by /proc/sys/kernel/numa_balancing. Due to the above case, we want to disable/enable numa_balancing per-process instead. Set per-process numa balancing: prctl(PR_NUMA_BALANCING, PR_SET_NUMA_BALANCING_DISABLE); //disable prctl(PR_NUMA_BALANCING, PR_SET_NUMA_BALANCING_ENABLE); //enable prctl(PR_NUMA_BALANCING, PR_SET_NUMA_BALANCING_DEFAULT); //follow global Get numa_balancing state: prctl(PR_NUMA_BALANCING, PR_GET_NUMA_BALANCING, &ret); cat /proc/<pid>/status | grep NumaB_mode # Unixbench multithread result I ran benchmark 20 times, but still have measurement error. I will run benchmark more precisely on the next version of this patchset. +-------------------+----------+ | NAME | OVERHEAD | +-------------------+----------+ | Dhrystone2 | -0.27% | | Whetstone | -0.17% | | Execl | -0.92% | | File_Copy_1024 | 0.31% | | File_Copy_256 | -1.96% | | File_Copy_4096 | 0.40% | | Pipe_Throughput | -3.08% | | Context_Switching | -1.11% | | Process_Creation | 3.24% | | Shell_Scripts_1 | 0.26% | | Shell_Scripts_8 | 0.32% | | System_Call | 0.10% | +-------------------+----------+ | Total | -0.21% | +-------------------+----------+ # Changes Changes in v5: - replace numab_enabled with numa_balancing_mode (Peter Zijlstra) - make numa_balancing_enabled and numa_balancing_mode inline (Peter Zijlstra) - use static_branch_inc/dec instead of static_branch_enable/disable (Peter Zijlstra) - delete CONFIG_NUMA_BALANCING in task_tick_fair (Peter Zijlstra) - reword commit, use imperative mood (Bagas Sanjaya) - Unixbench overhead result Changes in v4: - code clean: add wrapper function `numa_balancing_enabled` Changes in v3: - Fix compile error. Changes in v2: - Now PR_NUMA_BALANCING support three states: enabled, disabled, default. enabled and disabled will ignore global setting, and default will follow global setting. Gang Li (2): sched/numa: use static_branch_inc/dec for sched_numa_balancing sched/numa: add per-process numa_balancing Documentation/filesystems/proc.rst | 2 ++ fs/proc/task_mmu.c | 20 ++++++++++++ include/linux/mm_types.h | 3 ++ include/linux/sched/numa_balancing.h | 45 ++++++++++++++++++++++++++ include/uapi/linux/prctl.h | 7 +++++ kernel/fork.c | 4 +++ kernel/sched/core.c | 26 +++++++-------- kernel/sched/fair.c | 9 +++--- kernel/sys.c | 47 ++++++++++++++++++++++++++++ mm/mprotect.c | 6 ++-- 10 files changed, 150 insertions(+), 19 deletions(-) -- 2.20.1
