kernel.git/kernel/sched/sched.h, 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

sched/uclamp: Fix fits_capacity() check in feec()

2022-12-31T12:25:41Z

[ Upstream commit 244226035a1f9b2b6c326e55ae5188fab4f428cb ] As reported by Yun Hsiang [1], if a task has its uclamp_min >= 0.8 * 1024, it'll always pick the previous CPU because fits_capacity() will always return false in this case. The new util_fits_cpu() logic should handle this correctly for us beside more corner cases where similar failures could occur, like when using UCLAMP_MAX. We open code uclamp_rq_util_with() except for the clamp() part, util_fits_cpu() needs the 'raw' values to be passed to it. Also introduce uclamp_rq_{set, get}() shorthand accessors to get uclamp value for the rq. Makes the code more readable and ensures the right rules (use READ_ONCE/WRITE_ONCE) are respected transparently. [1] https://lists.linaro.org/pipermail/eas-dev/2020-July/001488.html Fixes: 1d42509e475c ("sched/fair: Make EAS wakeup placement consider uclamp restrictions") Reported-by: Yun Hsiang Signed-off-by: Qais Yousef Signed-off-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20220804143609.515789-4-qais.yousef@arm.com Signed-off-by: Sasha Levin

sched/uclamp: Make task_fits_capacity() use util_fits_cpu()

2022-12-31T12:25:41Z

[ Upstream commit b48e16a69792b5dc4a09d6807369d11b2970cc36 ] So that the new uclamp rules in regard to migration margin and capacity pressure are taken into account correctly. Fixes: a7008c07a568 ("sched/fair: Make task_fits_capacity() consider uclamp restrictions") Co-developed-by: Vincent Guittot Signed-off-by: Qais Yousef Signed-off-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20220804143609.515789-3-qais.yousef@arm.com Signed-off-by: Sasha Levin

sched/core: Fix comparison in sched_group_cookie_match()

2022-11-03T15:00:27Z

[ Upstream commit e705968dd687574b6ca3ebe772683d5642759132 ] In commit 97886d9dcd86 ("sched: Migration changes for core scheduling"), sched_group_cookie_match() was added to help determine if a cookie matches the core state. However, while it iterates the SMT group, it fails to actually use the RQ for each of the CPUs iterated, use cpu_rq(cpu) instead of rq to fix things. Fixes: 97886d9dcd86 ("sched: Migration changes for core scheduling") Signed-off-by: Lin Shengwang Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20221008022709.642-1-linshengwang1@huawei.com Signed-off-by: Sasha Levin

Merge tag 'sched-urgent-2022-08-06' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2022-08-07T00:34:06Z

Pull scheduler fixes from Ingo Molnar: "Various fixes: a deadline scheduler fix, a migration fix, a Sparse fix and a comment fix" * tag 'sched-urgent-2022-08-06' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/core: Do not requeue task on CPU excluded from cpus_mask sched/rt: Fix Sparse warnings due to undefined rt.c declarations exit: Fix typo in comment: s/sub-theads/sub-threads sched, cpuset: Fix dl_cpu_busy() panic due to empty cs->cpus_allowed

sched/rt: Fix Sparse warnings due to undefined rt.c declarations

2022-08-03T09:22:37Z

There are several symbols defined in kernel/sched/sched.h but get wrapped in CONFIG_CGROUP_SCHED, even though dummy versions get built in rt.c and therefore trigger Sparse warnings: kernel/sched/rt.c:309:6: warning: symbol 'unregister_rt_sched_group' was not declared. Should it be static? kernel/sched/rt.c:311:6: warning: symbol 'free_rt_sched_group' was not declared. Should it be static? kernel/sched/rt.c:313:5: warning: symbol 'alloc_rt_sched_group' was not declared. Should it be static? Fix this by moving them outside the CONFIG_CGROUP_SCHED block. [ mingo: Refreshed to the latest scheduler tree, tweaked changelog. ] Signed-off-by: Ben Dooks Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20220721145155.358366-1-ben-linux@fluff.org

Merge tag 'rcu.2022.07.26a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu

2022-08-03T02:12:45Z

Pull RCU updates from Paul McKenney: - Documentation updates - Miscellaneous fixes - Callback-offload updates, perhaps most notably a new RCU_NOCB_CPU_DEFAULT_ALL Kconfig option that causes all CPUs to be offloaded at boot time, regardless of kernel boot parameters. This is useful to battery-powered systems such as ChromeOS and Android. In addition, a new RCU_NOCB_CPU_CB_BOOST kernel boot parameter prevents offloaded callbacks from interfering with real-time workloads and with energy-efficiency mechanisms - Polled grace-period updates, perhaps most notably making these APIs account for both normal and expedited grace periods - Tasks RCU updates, perhaps most notably reducing the CPU overhead of RCU tasks trace grace periods by more than a factor of two on a system with 15,000 tasks. The reduction is expected to increase with the number of tasks, so it seems reasonable to hypothesize that a system with 150,000 tasks might see a 20-fold reduction in CPU overhead - Torture-test updates - Updates that merge RCU's dyntick-idle tracking into context tracking, thus reducing the overhead of transitioning to kernel mode from either idle or nohz_full userspace execution for kernels that track context independently of RCU. This is expected to be helpful primarily for kernels built with CONFIG_NO_HZ_FULL=y * tag 'rcu.2022.07.26a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu: (98 commits) rcu: Add irqs-disabled indicator to expedited RCU CPU stall warnings rcu: Diagnose extended sync_rcu_do_polled_gp() loops rcu: Put panic_on_rcu_stall() after expedited RCU CPU stall warnings rcutorture: Test polled expedited grace-period primitives rcu: Add polled expedited grace-period primitives rcutorture: Verify that polled GP API sees synchronous grace periods rcu: Make Tiny RCU grace periods visible to polled APIs rcu: Make polled grace-period API account for expedited grace periods rcu: Switch polled grace-period APIs to ->gp_seq_polled rcu/nocb: Avoid polling when my_rdp->nocb_head_rdp list is empty rcu/nocb: Add option to opt rcuo kthreads out of RT priority rcu: Add nocb_cb_kthread check to rcu_is_callbacks_kthread() rcu/nocb: Add an option to offload all CPUs on boot rcu/nocb: Fix NOCB kthreads spawn failure with rcu_nocb_rdp_deoffload() direct call rcu/nocb: Invert rcu_state.barrier_mutex VS hotplug lock locking order rcu/nocb: Add/del rdp to iterate from rcuog itself rcu/tree: Add comment to describe GP-done condition in fqs loop rcu: Initialize first_gp_fqs at declaration in rcu_gp_fqs() rcu/kvfree: Remove useless monitor_todo flag rcu: Cleanup RCU urgency state for offline CPU ...

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 ...

context_tracking: Take idle eqs entrypoints over RCU

2022-07-05T20:32:16Z

The RCU dynticks counter is going to be merged into the context tracking subsystem. Start with moving the idle extended quiescent states entrypoints to context tracking. For now those are dumb redirections to existing RCU calls. [ paulmck: Apply kernel test robot feedback. ] Signed-off-by: Frederic Weisbecker Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Neeraj Upadhyay Cc: Uladzislau Rezki Cc: Joel Fernandes Cc: Boqun Feng Cc: Nicolas Saenz Julienne Cc: Marcelo Tosatti Cc: Xiongfeng Wang Cc: Yu Liao Cc: Phil Auld Cc: Paul Gortmaker Cc: Alex Belits Signed-off-by: Paul E. McKenney Reviewed-by: Nicolas Saenz Julienne Tested-by: Nicolas Saenz Julienne

sched, drivers: Remove max param from effective_cpu_util()/sched_cpu_util()

2022-06-28T07:17:46Z

effective_cpu_util() already has a `int cpu' parameter which allows to retrieve the CPU capacity scale factor (or maximum CPU capacity) inside this function via an arch_scale_cpu_capacity(cpu). A lot of code calling effective_cpu_util() (or the shim sched_cpu_util()) needs the maximum CPU capacity, i.e. it will call arch_scale_cpu_capacity() already. But not having to pass it into effective_cpu_util() will make the EAS wake-up code easier, especially when the maximum CPU capacity reduced by the thermal pressure is passed through the EAS wake-up functions. Due to the asymmetric CPU capacity support of arm/arm64 architectures, arch_scale_cpu_capacity(int cpu) is a per-CPU variable read access via per_cpu(cpu_scale, cpu) on such a system. On all other architectures it is a a compile-time constant (SCHED_CAPACITY_SCALE). Signed-off-by: Dietmar Eggemann Signed-off-by: Peter Zijlstra (Intel) Acked-by: Vincent Guittot Tested-by: Lukasz Luba Link: https://lkml.kernel.org/r/20220621090414.433602-4-vdonnefort@google.com