kernel.git/kernel/sched/core.c, branch linux-6.4.y

cgroup/cpuset: Free DL BW in case can_attach() fails

2023-08-30T12:52:39Z

commit 2ef269ef1ac006acf974793d975539244d77b28f upstream. cpuset_can_attach() can fail. Postpone DL BW allocation until all tasks have been checked. DL BW is not allocated per-task but as a sum over all DL tasks migrating. If multiple controllers are attached to the cgroup next to the cpuset controller a non-cpuset can_attach() can fail. In this case free DL BW in cpuset_cancel_attach(). Finally, update cpuset DL task count (nr_deadline_tasks) only in cpuset_attach(). Suggested-by: Waiman Long Signed-off-by: Dietmar Eggemann Signed-off-by: Juri Lelli Reviewed-by: Waiman Long Signed-off-by: Tejun Heo Signed-off-by: Qais Yousef (Google) Signed-off-by: Greg Kroah-Hartman

sched/deadline: Create DL BW alloc, free & check overflow interface

2023-08-30T12:52:39Z

commit 85989106feb734437e2d598b639991b9185a43a6 upstream. While moving a set of tasks between exclusive cpusets, cpuset_can_attach() -> task_can_attach() calls dl_cpu_busy(..., p) for DL BW overflow checking and per-task DL BW allocation on the destination root_domain for the DL tasks in this set. This approach has the issue of not freeing already allocated DL BW in the following error cases: (1) The set of tasks includes multiple DL tasks and DL BW overflow checking fails for one of the subsequent DL tasks. (2) Another controller next to the cpuset controller which is attached to the same cgroup fails in its can_attach(). To address this problem rework dl_cpu_busy(): (1) Split it into dl_bw_check_overflow() & dl_bw_alloc() and add a dedicated dl_bw_free(). (2) dl_bw_alloc() & dl_bw_free() take a `u64 dl_bw` parameter instead of a `struct task_struct *p` used in dl_cpu_busy(). This allows to allocate DL BW for a set of tasks too rather than only for a single task. Signed-off-by: Dietmar Eggemann Signed-off-by: Juri Lelli Signed-off-by: Tejun Heo Signed-off-by: Qais Yousef (Google) Signed-off-by: Greg Kroah-Hartman

sched/cpuset: Bring back cpuset_mutex

2023-08-30T12:52:38Z

commit 111cd11bbc54850f24191c52ff217da88a5e639b upstream. Turns out percpu_cpuset_rwsem - commit 1243dc518c9d ("cgroup/cpuset: Convert cpuset_mutex to percpu_rwsem") - wasn't such a brilliant idea, as it has been reported to cause slowdowns in workloads that need to change cpuset configuration frequently and it is also not implementing priority inheritance (which causes troubles with realtime workloads). Convert percpu_cpuset_rwsem back to regular cpuset_mutex. Also grab it only for SCHED_DEADLINE tasks (other policies don't care about stable cpusets anyway). Signed-off-by: Juri Lelli Reviewed-by: Waiman Long Signed-off-by: Tejun Heo Signed-off-by: Qais Yousef (Google) Signed-off-by: Greg Kroah-Hartman

sched: fix cid_lock kernel-doc warnings

2023-05-08T08:58:28Z

Fix kernel-doc warnings for cid_lock and use_cid_lock. These comments are not in kernel-doc format. kernel/sched/core.c:11496: warning: Cannot understand * @cid_lock: Guarantee forward-progress of cid allocation. on line 11496 - I thought it was a doc line kernel/sched/core.c:11505: warning: Cannot understand * @use_cid_lock: Select cid allocation behavior: lock-free vs spinlock. on line 11505 - I thought it was a doc line Fixes: 223baf9d17f2 ("sched: Fix performance regression introduced by mm_cid") Signed-off-by: Randy Dunlap Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20230428031111.322-1-rdunlap@infradead.org

Merge tag 'smp-core-2023-04-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2023-04-28T22:03:43Z

Pull SMP cross-CPU function-call updates from Ingo Molnar: - Remove diagnostics and adjust config for CSD lock diagnostics - Add a generic IPI-sending tracepoint, as currently there's no easy way to instrument IPI origins: it's arch dependent and for some major architectures it's not even consistently available. * tag 'smp-core-2023-04-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: trace,smp: Trace all smp_function_call*() invocations trace: Add trace_ipi_send_cpu() sched, smp: Trace smp callback causing an IPI smp: reword smp call IPI comment treewide: Trace IPIs sent via smp_send_reschedule() irq_work: Trace self-IPIs sent via arch_irq_work_raise() smp: Trace IPIs sent via arch_send_call_function_ipi_mask() sched, smp: Trace IPIs sent via send_call_function_single_ipi() trace: Add trace_ipi_send_cpumask() kernel/smp: Make csdlock_debug= resettable locking/csd_lock: Remove per-CPU data indirection from CSD lock debugging locking/csd_lock: Remove added data from CSD lock debugging locking/csd_lock: Add Kconfig option for csd_debug default

Merge tag 'sched-core-2023-04-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2023-04-28T21:53:30Z

Pull scheduler updates from Ingo Molnar: - Allow unprivileged PSI poll()ing - Fix performance regression introduced by mm_cid - Improve livepatch stalls by adding livepatch task switching to cond_resched(). This resolves livepatching busy-loop stalls with certain CPU-bound kthreads - Improve sched_move_task() performance on autogroup configs - On core-scheduling CPUs, avoid selecting throttled tasks to run - Misc cleanups, fixes and improvements * tag 'sched-core-2023-04-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/clock: Fix local_clock() before sched_clock_init() sched/rt: Fix bad task migration for rt tasks sched: Fix performance regression introduced by mm_cid sched/core: Make sched_dynamic_mutex static sched/psi: Allow unprivileged polling of N*2s period sched/psi: Extract update_triggers side effect sched/psi: Rename existing poll members in preparation sched/psi: Rearrange polling code in preparation sched/fair: Fix inaccurate tally of ttwu_move_affine vhost: Fix livepatch timeouts in vhost_worker() livepatch,sched: Add livepatch task switching to cond_resched() livepatch: Skip task_call_func() for current task livepatch: Convert stack entries array to percpu sched: Interleave cfs bandwidth timers for improved single thread performance at low utilization sched/core: Reduce cost of sched_move_task when config autogroup sched/core: Avoid selecting the task that is throttled to run when core-sched enable sched/topology: Make sched_energy_mutex,update static

Merge tag 'mm-nonmm-stable-2023-04-27-16-01' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2023-04-28T02:57:00Z

Pull non-MM updates from Andrew Morton: "Mainly singleton patches all over the place. Series of note are: - updates to scripts/gdb from Glenn Washburn - kexec cleanups from Bjorn Helgaas" * tag 'mm-nonmm-stable-2023-04-27-16-01' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (50 commits) mailmap: add entries for Paul Mackerras libgcc: add forward declarations for generic library routines mailmap: add entry for Oleksandr ocfs2: reduce ioctl stack usage fs/proc: add Kthread flag to /proc/$pid/status ia64: fix an addr to taddr in huge_pte_offset() checkpatch: introduce proper bindings license check epoll: rename global epmutex scripts/gdb: add GDB convenience functions $lx_dentry_name() and $lx_i_dentry() scripts/gdb: create linux/vfs.py for VFS related GDB helpers uapi/linux/const.h: prefer ISO-friendly __typeof__ delayacct: track delays from IRQ/SOFTIRQ scripts/gdb: timerlist: convert int chunks to str scripts/gdb: print interrupts scripts/gdb: raise error with reduced debugging information scripts/gdb: add a Radix Tree Parser lib/rbtree: use '+' instead of '|' for setting color. proc/stat: remove arch_idle_time() checkpatch: check for misuse of the link tags checkpatch: allow Closes tags with links ...

sched: Fix performance regression introduced by mm_cid

2023-04-21T11:24:20Z

Introduce per-mm/cpu current concurrency id (mm_cid) to fix a PostgreSQL sysbench regression reported by Aaron Lu. Keep track of the currently allocated mm_cid for each mm/cpu rather than freeing them immediately on context switch. This eliminates most atomic operations when context switching back and forth between threads belonging to different memory spaces in multi-threaded scenarios (many processes, each with many threads). The per-mm/per-cpu mm_cid values are serialized by their respective runqueue locks. Thread migration is handled by introducing invocation to sched_mm_cid_migrate_to() (with destination runqueue lock held) in activate_task() for migrating tasks. If the destination cpu's mm_cid is unset, and if the source runqueue is not actively using its mm_cid, then the source cpu's mm_cid is moved to the destination cpu on migration. Introduce a task-work executed periodically, similarly to NUMA work, which delays reclaim of cid values when they are unused for a period of time. Keep track of the allocation time for each per-cpu cid, and let the task work clear them when they are observed to be older than SCHED_MM_CID_PERIOD_NS and unused. This task work also clears all mm_cids which are greater or equal to the Hamming weight of the mm cidmask to keep concurrency ids compact. Because we want to ensure the mm_cid converges towards the smaller values as migrations happen, the prior optimization that was done when context switching between threads belonging to the same mm is removed, because it could delay the lazy release of the destination runqueue mm_cid after it has been replaced by a migration. Removing this prior optimization is not an issue performance-wise because the introduced per-mm/per-cpu mm_cid tracking also covers this more specific case. Fixes: af7f588d8f73 ("sched: Introduce per-memory-map concurrency ID") Reported-by: Aaron Lu Signed-off-by: Mathieu Desnoyers Signed-off-by: Peter Zijlstra (Intel) Tested-by: Aaron Lu Link: https://lore.kernel.org/lkml/20230327080502.GA570847@ziqianlu-desk2/

Merge branch 'v6.3-rc7'

2023-04-21T11:24:18Z

Sync with the urgent patches; in particular: a53ce18cacb4 ("sched/fair: Sanitize vruntime of entity being migrated") Signed-off-by: Peter Zijlstra

delayacct: track delays from IRQ/SOFTIRQ

2023-04-18T23:39:34Z

Delay accounting does not track the delay of IRQ/SOFTIRQ. While IRQ/SOFTIRQ could have obvious impact on some workloads productivity, such as when workloads are running on system which is busy handling network IRQ/SOFTIRQ. Get the delay of IRQ/SOFTIRQ could help users to reduce such delay. Such as setting interrupt affinity or task affinity, using kernel thread for NAPI etc. This is inspired by "sched/psi: Add PSI_IRQ to track IRQ/SOFTIRQ pressure"[1]. Also fix some code indent problems of older code. And update tools/accounting/getdelays.c: / # ./getdelays -p 156 -di print delayacct stats ON printing IO accounting PID 156 CPU count real total virtual total delay total delay average 15 15836008 16218149 275700790 18.380ms IO count delay total delay average 0 0 0.000ms SWAP count delay total delay average 0 0 0.000ms RECLAIM count delay total delay average 0 0 0.000ms THRASHING count delay total delay average 0 0 0.000ms COMPACT count delay total delay average 0 0 0.000ms WPCOPY count delay total delay average 36 7586118 0.211ms IRQ count delay total delay average 42 929161 0.022ms [1] commit 52b1364ba0b1("sched/psi: Add PSI_IRQ to track IRQ/SOFTIRQ pressure") Link: https://lkml.kernel.org/r/202304081728353557233@zte.com.cn Signed-off-by: Yang Yang Cc: Jiang Xuexin Cc: wangyong Cc: junhua huang Cc: Balbir Singh Cc: Ingo Molnar Cc: Jonathan Corbet Cc: Juri Lelli Cc: Peter Zijlstra Signed-off-by: Andrew Morton