kernel.git/kernel/sched/deadline.c, branch linux-6.0.y

sched/core: Introduce sched_asym_cpucap_active()

2022-12-31T12:25:41Z

[ Upstream commit 740cf8a760b73e8375bfb4bedcbe9746183350f9 ] Create an inline helper for conditional code to be only executed on asymmetric CPU capacity systems. This makes these (currently ~10 and future) conditions a lot more readable. Signed-off-by: Dietmar Eggemann Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20220729111305.1275158-2-dietmar.eggemann@arm.com Stable-dep-of: a2e7f03ed28f ("sched/uclamp: Make asym_fits_capacity() use util_fits_cpu()") Signed-off-by: Sasha Levin

Merge tag 'sched-core-2022-08-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2022-08-01T18:49:06Z

Pull scheduler updates from Ingo Molnar: "Load-balancing improvements: - Improve NUMA balancing on AMD Zen systems for affine workloads. - Improve the handling of reduced-capacity CPUs in load-balancing. - Energy Model improvements: fix & refine all the energy fairness metrics (PELT), and remove the conservative threshold requiring 6% energy savings to migrate a task. Doing this improves power efficiency for most workloads, and also increases the reliability of energy-efficiency scheduling. - Optimize/tweak select_idle_cpu() to spend (much) less time searching for an idle CPU on overloaded systems. There's reports of several milliseconds spent there on large systems with large workloads ... [ Since the search logic changed, there might be behavioral side effects. ] - Improve NUMA imbalance behavior. On certain systems with spare capacity, initial placement of tasks is non-deterministic, and such an artificial placement imbalance can persist for a long time, hurting (and sometimes helping) performance. The fix is to make fork-time task placement consistent with runtime NUMA balancing placement. Note that some performance regressions were reported against this, caused by workloads that are not memory bandwith limited, which benefit from the artificial locality of the placement bug(s). Mel Gorman's conclusion, with which we concur, was that consistency is better than random workload benefits from non-deterministic bugs: "Given there is no crystal ball and it's a tradeoff, I think it's better to be consistent and use similar logic at both fork time and runtime even if it doesn't have universal benefit." - Improve core scheduling by fixing a bug in sched_core_update_cookie() that caused unnecessary forced idling. - Improve wakeup-balancing by allowing same-LLC wakeup of idle CPUs for newly woken tasks. - Fix a newidle balancing bug that introduced unnecessary wakeup latencies. ABI improvements/fixes: - Do not check capabilities and do not issue capability check denial messages when a scheduler syscall doesn't require privileges. (Such as increasing niceness.) - Add forced-idle accounting to cgroups too. - Fix/improve the RSEQ ABI to not just silently accept unknown flags. (No existing tooling is known to have learned to rely on the previous behavior.) - Depreciate the (unused) RSEQ_CS_FLAG_NO_RESTART_ON_* flags. Optimizations: - Optimize & simplify leaf_cfs_rq_list() - Micro-optimize set_nr_{and_not,if}_polling() via try_cmpxchg(). Misc fixes & cleanups: - Fix the RSEQ self-tests on RISC-V and Glibc 2.35 systems. - Fix a full-NOHZ bug that can in some cases result in the tick not being re-enabled when the last SCHED_RT task is gone from a runqueue but there's still SCHED_OTHER tasks around. - Various PREEMPT_RT related fixes. - Misc cleanups & smaller fixes" * tag 'sched-core-2022-08-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (32 commits) rseq: Kill process when unknown flags are encountered in ABI structures rseq: Deprecate RSEQ_CS_FLAG_NO_RESTART_ON_* flags sched/core: Fix the bug that task won't enqueue into core tree when update cookie nohz/full, sched/rt: Fix missed tick-reenabling bug in dequeue_task_rt() sched/core: Always flush pending blk_plug sched/fair: fix case with reduced capacity CPU sched/core: Use try_cmpxchg in set_nr_{and_not,if}_polling sched/core: add forced idle accounting for cgroups sched/fair: Remove the energy margin in feec() sched/fair: Remove task_util from effective utilization in feec() sched/fair: Use the same cpumask per-PD throughout find_energy_efficient_cpu() sched/fair: Rename select_idle_mask to select_rq_mask sched, drivers: Remove max param from effective_cpu_util()/sched_cpu_util() sched/fair: Decay task PELT values during wakeup migration sched/fair: Provide u64 read for 32-bits arch helper sched/fair: Introduce SIS_UTIL to search idle CPU based on sum of util_avg sched: only perform capability check on privileged operation sched: Remove unused function group_first_cpu() sched/fair: Remove redundant word " *" selftests/rseq: check if libc rseq support is registered ...

sched/deadline: Fix BUG_ON condition for deboosted tasks

2022-07-21T08:35:28Z

Tasks the are being deboosted from SCHED_DEADLINE might enter enqueue_task_dl() one last time and hit an erroneous BUG_ON condition: since they are not boosted anymore, the if (is_dl_boosted()) branch is not taken, but the else if (!dl_prio) is and inside this one we BUG_ON(!is_dl_boosted), which is of course false (BUG_ON triggered) otherwise we had entered the if branch above. Long story short, the current condition doesn't make sense and always leads to triggering of a BUG. Fix this by only checking enqueue flags, properly: ENQUEUE_REPLENISH has to be present, but additional flags are not a problem. Fixes: 64be6f1f5f71 ("sched/deadline: Don't replenish from a !SCHED_DEADLINE entity") Signed-off-by: Juri Lelli Signed-off-by: Peter Zijlstra (Intel) Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20220714151908.533052-1-juri.lelli@redhat.com

sched/deadline: Use proc_douintvec_minmax() limit minimum value

2022-06-13T08:30:00Z

sysctl_sched_dl_period_max and sysctl_sched_dl_period_min are unsigned integer, but proc_dointvec() wouldn't return error even if we set a negative number. Use proc_douintvec_minmax() instead of proc_dointvec(). Add extra1 for sysctl_sched_dl_period_max and extra2 for sysctl_sched_dl_period_min. It's just an optimization for match data and proc_handler in struct ctl_table. The 'if (period < min || period > max)' in __checkparam_dl() will work fine even if there hasn't this patch. Signed-off-by: Yajun Deng Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Daniel Bristot de Oliveira Link: https://lore.kernel.org/r/20220607101807.249965-1-yajun.deng@linux.dev

Merge tag 'sysctl-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux

2022-05-26T23:57:20Z

Pull sysctl updates from Luis Chamberlain: "For two kernel releases now kernel/sysctl.c has been being cleaned up slowly, since the tables were grossly long, sprinkled with tons of #ifdefs and all this caused merge conflicts with one susbystem or another. This tree was put together to help try to avoid conflicts with these cleanups going on different trees at time. So nothing exciting on this pull request, just cleanups. Thanks a lot to the Uniontech and Huawei folks for doing some of this nasty work" * tag 'sysctl-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux: (28 commits) sched: Fix build warning without CONFIG_SYSCTL reboot: Fix build warning without CONFIG_SYSCTL kernel/kexec_core: move kexec_core sysctls into its own file sysctl: minor cleanup in new_dir() ftrace: fix building with SYSCTL=y but DYNAMIC_FTRACE=n fs/proc: Introduce list_for_each_table_entry for proc sysctl mm: fix unused variable kernel warning when SYSCTL=n latencytop: move sysctl to its own file ftrace: fix building with SYSCTL=n but DYNAMIC_FTRACE=y ftrace: Fix build warning ftrace: move sysctl_ftrace_enabled to ftrace.c kernel/do_mount_initrd: move real_root_dev sysctls to its own file kernel/delayacct: move delayacct sysctls to its own file kernel/acct: move acct sysctls to its own file kernel/panic: move panic sysctls to its own file kernel/lockdep: move lockdep sysctls to its own file mm: move page-writeback sysctls to their own file mm: move oom_kill sysctls to their own file kernel/reboot: move reboot sysctls to its own file sched: Move energy_aware sysctls to topology.c ...

sched/deadline: Remove superfluous rq clock update in push_dl_task()

2022-05-11T14:27:12Z

The change to call update_rq_clock() before activate_task() commit 840d719604b0 ("sched/deadline: Update rq_clock of later_rq when pushing a task") is no longer needed since commit f4904815f97a ("sched/deadline: Fix double accounting of rq/running bw in push & pull") removed the add_running_bw() before the activate_task(). So we remove some comments that are no longer needed and update rq clock in activate_task(). Signed-off-by: Hao Jia Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Dietmar Eggemann Reviewed-by: Daniel Bristot de Oliveira Link: https://lore.kernel.org/r/20220430085843.62939-3-jiahao.os@bytedance.com

sched/core: Avoid obvious double update_rq_clock warning

2022-05-11T14:27:11Z

When we use raw_spin_rq_lock() to acquire the rq lock and have to update the rq clock while holding the lock, the kernel may issue a WARN_DOUBLE_CLOCK warning. Since we directly use raw_spin_rq_lock() to acquire rq lock instead of rq_lock(), there is no corresponding change to rq->clock_update_flags. In particular, we have obtained the rq lock of other CPUs, the rq->clock_update_flags of this CPU may be RQCF_UPDATED at this time, and then calling update_rq_clock() will trigger the WARN_DOUBLE_CLOCK warning. So we need to clear RQCF_UPDATED of rq->clock_update_flags to avoid the WARN_DOUBLE_CLOCK warning. For the sched_rt_period_timer() and migrate_task_rq_dl() cases we simply replace raw_spin_rq_lock()/raw_spin_rq_unlock() with rq_lock()/rq_unlock(). For the {pull,push}_{rt,dl}_task() cases, we add the double_rq_clock_clear_update() function to clear RQCF_UPDATED of rq->clock_update_flags, and call double_rq_clock_clear_update() before double_lock_balance()/double_rq_lock() returns to avoid the WARN_DOUBLE_CLOCK warning. Some call trace reports: Call Trace 1: sched_rt_period_timer+0x10f/0x3a0 ? enqueue_top_rt_rq+0x110/0x110 __hrtimer_run_queues+0x1a9/0x490 hrtimer_interrupt+0x10b/0x240 __sysvec_apic_timer_interrupt+0x8a/0x250 sysvec_apic_timer_interrupt+0x9a/0xd0 asm_sysvec_apic_timer_interrupt+0x12/0x20 Call Trace 2: activate_task+0x8b/0x110 push_rt_task.part.108+0x241/0x2c0 push_rt_tasks+0x15/0x30 finish_task_switch+0xaa/0x2e0 ? __switch_to+0x134/0x420 __schedule+0x343/0x8e0 ? hrtimer_start_range_ns+0x101/0x340 schedule+0x4e/0xb0 do_nanosleep+0x8e/0x160 hrtimer_nanosleep+0x89/0x120 ? hrtimer_init_sleeper+0x90/0x90 __x64_sys_nanosleep+0x96/0xd0 do_syscall_64+0x34/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae Call Trace 3: deactivate_task+0x93/0xe0 pull_rt_task+0x33e/0x400 balance_rt+0x7e/0x90 __schedule+0x62f/0x8e0 do_task_dead+0x3f/0x50 do_exit+0x7b8/0xbb0 do_group_exit+0x2d/0x90 get_signal+0x9df/0x9e0 ? preempt_count_add+0x56/0xa0 ? __remove_hrtimer+0x35/0x70 arch_do_signal_or_restart+0x36/0x720 ? nanosleep_copyout+0x39/0x50 ? do_nanosleep+0x131/0x160 ? audit_filter_inodes+0xf5/0x120 exit_to_user_mode_prepare+0x10f/0x1e0 syscall_exit_to_user_mode+0x17/0x30 do_syscall_64+0x40/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae Call Trace 4: update_rq_clock+0x128/0x1a0 migrate_task_rq_dl+0xec/0x310 set_task_cpu+0x84/0x1e4 try_to_wake_up+0x1d8/0x5c0 wake_up_process+0x1c/0x30 hrtimer_wakeup+0x24/0x3c __hrtimer_run_queues+0x114/0x270 hrtimer_interrupt+0xe8/0x244 arch_timer_handler_phys+0x30/0x50 handle_percpu_devid_irq+0x88/0x140 generic_handle_domain_irq+0x40/0x60 gic_handle_irq+0x48/0xe0 call_on_irq_stack+0x2c/0x60 do_interrupt_handler+0x80/0x84 Steps to reproduce: 1. Enable CONFIG_SCHED_DEBUG when compiling the kernel 2. echo 1 > /sys/kernel/debug/clear_warn_once echo "WARN_DOUBLE_CLOCK" > /sys/kernel/debug/sched/features echo "NO_RT_PUSH_IPI" > /sys/kernel/debug/sched/features 3. Run some rt/dl tasks that periodically work and sleep, e.g. Create 2*n rt or dl (90% running) tasks via rt-app (on a system with n CPUs), and Dietmar Eggemann reports Call Trace 4 when running on PREEMPT_RT kernel. Signed-off-by: Hao Jia Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Dietmar Eggemann Link: https://lore.kernel.org/r/20220430085843.62939-2-jiahao.os@bytedance.com

sched: Fix missing prototype warnings

2022-05-01T08:03:43Z

A W=1 build emits more than a dozen missing prototype warnings related to scheduler and scheduler specific includes. Reported-by: kernel test robot Signed-off-by: Thomas Gleixner Acked-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20220413133024.249118058@linutronix.de

sched: Move deadline_period sysctls to deadline.c

2022-04-06T20:43:43Z

move deadline_period sysctls to deadline.c and use the new register_sysctl_init() to register the sysctl interface. Signed-off-by: Zhen Ni Signed-off-by: Luis Chamberlain

Merge branch 'sched/fast-headers' into sched/core

2022-03-15T08:05:05Z

Merge the scheduler build speedup of the fast-headers tree. Cumulative scheduler (kernel/sched/) build time speedup on a Linux distribution's config, which enables all scheduler features, compared to the vanilla kernel: _____________________________________________________________________________ | | Vanilla kernel (v5.13-rc7): |_____________________________________________________________________________ | | Performance counter stats for 'make -j96 kernel/sched/' (3 runs): | | 126,975,564,374 instructions # 1.45 insn per cycle ( +- 0.00% ) | 87,637,847,671 cycles # 3.959 GHz ( +- 0.30% ) | 22,136.96 msec cpu-clock # 7.499 CPUs utilized ( +- 0.29% ) | | 2.9520 +- 0.0169 seconds time elapsed ( +- 0.57% ) |_____________________________________________________________________________ | | Patched kernel: |_____________________________________________________________________________ | | Performance counter stats for 'make -j96 kernel/sched/' (3 runs): | | 50,420,496,914 instructions # 1.47 insn per cycle ( +- 0.00% ) | 34,234,322,038 cycles # 3.946 GHz ( +- 0.31% ) | 8,675.81 msec cpu-clock # 3.053 CPUs utilized ( +- 0.45% ) | | 2.8420 +- 0.0181 seconds time elapsed ( +- 0.64% ) |_____________________________________________________________________________ Summary: - CPU time used to build the scheduler dropped by -60.9%, a reduction from 22.1 clock-seconds to 8.7 clock-seconds. - Wall-clock time to build the scheduler dropped by -3.9%, a reduction from 2.95 seconds to 2.84 seconds. Signed-off-by: Ingo Molnar