user/sven/linux.git/include/linux/smp.h, branch v5.9.8

smp, irq_work: Continue smp_call_function() and irq_work() integration

2020-06-28T15:01:20Z

Instead of relying on BUG_ON() to ensure the various data structures line up, use a bunch of horrible unions to make it all automatic. Much of the union magic is to ensure irq_work and smp_call_function do not (yet) see the members of their respective data structures change name. Suggested-by: Linus Torvalds Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Reviewed-by: Frederic Weisbecker Link: https://lkml.kernel.org/r/20200622100825.844455025@infradead.org

Merge tag 'sched-core-2020-06-02' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2020-06-03T20:06:42Z

Pull scheduler updates from Ingo Molnar: "The changes in this cycle are: - Optimize the task wakeup CPU selection logic, to improve scalability and reduce wakeup latency spikes - PELT enhancements - CFS bandwidth handling fixes - Optimize the wakeup path by remove rq->wake_list and replacing it with ->ttwu_pending - Optimize IPI cross-calls by making flush_smp_call_function_queue() process sync callbacks first. - Misc fixes and enhancements" * tag 'sched-core-2020-06-02' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (36 commits) irq_work: Define irq_work_single() on !CONFIG_IRQ_WORK too sched/headers: Split out open-coded prototypes into kernel/sched/smp.h sched: Replace rq::wake_list sched: Add rq::ttwu_pending irq_work, smp: Allow irq_work on call_single_queue smp: Optimize send_call_function_single_ipi() smp: Move irq_work_run() out of flush_smp_call_function_queue() smp: Optimize flush_smp_call_function_queue() sched: Fix smp_call_function_single_async() usage for ILB sched/core: Offload wakee task activation if it the wakee is descheduling sched/core: Optimize ttwu() spinning on p->on_cpu sched: Defend cfs and rt bandwidth quota against overflow sched/cpuacct: Fix charge cpuacct.usage_sys sched/fair: Replace zero-length array with flexible-array sched/pelt: Sync util/runnable_sum with PELT window when propagating sched/cpuacct: Use __this_cpu_add() instead of this_cpu_ptr() sched/fair: Optimize enqueue_task_fair() sched: Make scheduler_ipi inline sched: Clean up scheduler_ipi() sched/core: Simplify sched_init() ...

sched: Replace rq::wake_list

2020-05-28T08:54:16Z

The recent commit: 90b5363acd47 ("sched: Clean up scheduler_ipi()") got smp_call_function_single_async() subtly wrong. Even though it will return -EBUSY when trying to re-use a csd, that condition is not atomic and still requires external serialization. The change in ttwu_queue_remote() got this wrong. While on first reading ttwu_queue_remote() has an atomic test-and-set that appears to serialize the use, the matching 'release' is not in the right place to actually guarantee this serialization. The actual race is vs the sched_ttwu_pending() call in the idle loop; that can run the wakeup-list without consuming the CSD. Instead of trying to chain the lists, merge them. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20200526161908.129371594@infradead.org

irq_work, smp: Allow irq_work on call_single_queue

2020-05-28T08:54:15Z

Currently irq_work_queue_on() will issue an unconditional arch_send_call_function_single_ipi() and has the handler do irq_work_run(). This is unfortunate in that it makes the IPI handler look at a second cacheline and it misses the opportunity to avoid the IPI. Instead note that struct irq_work and struct __call_single_data are very similar in layout, so use a few bits in the flags word to encode a type and stick the irq_work on the call_single_queue list. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20200526161908.011635912@infradead.org

cpu/hotplug: Remove disable_nonboot_cpus()

2020-05-07T13:18:40Z

The single user could have called freeze_secondary_cpus() directly. Since this function was a source of confusion, remove it as it's just a pointless wrapper. While at it, rename enable_nonboot_cpus() to thaw_secondary_cpus() to preserve the naming symmetry. Done automatically via: git grep -l enable_nonboot_cpus | xargs sed -i 's/enable_nonboot_cpus/thaw_secondary_cpus/g' Signed-off-by: Qais Yousef Signed-off-by: Thomas Gleixner Cc: "Rafael J. Wysocki" Link: https://lkml.kernel.org/r/20200430114004.17477-1-qais.yousef@arm.com

smp: Remove allocation mask from on_each_cpu_cond.*()

2020-01-24T19:40:09Z

The allocation mask is no longer used by on_each_cpu_cond() and on_each_cpu_cond_mask() and can be removed. Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Thomas Gleixner Acked-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20200117090137.1205765-4-bigeasy@linutronix.de

smp: Use smp_cond_func_t as type for the conditional function

2020-01-24T19:40:08Z

Use a typdef for the conditional function instead defining it each time in the function prototype. Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Thomas Gleixner Acked-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20200117090137.1205765-2-bigeasy@linutronix.de

Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2019-07-08T23:12:03Z

Pull locking updates from Ingo Molnar: "The main changes in this cycle are: - rwsem scalability improvements, phase #2, by Waiman Long, which are rather impressive: "On a 2-socket 40-core 80-thread Skylake system with 40 reader and writer locking threads, the min/mean/max locking operations done in a 5-second testing window before the patchset were: 40 readers, Iterations Min/Mean/Max = 1,807/1,808/1,810 40 writers, Iterations Min/Mean/Max = 1,807/50,344/151,255 After the patchset, they became: 40 readers, Iterations Min/Mean/Max = 30,057/31,359/32,741 40 writers, Iterations Min/Mean/Max = 94,466/95,845/97,098" There's a lot of changes to the locking implementation that makes it similar to qrwlock, including owner handoff for more fair locking. Another microbenchmark shows how across the spectrum the improvements are: "With a locking microbenchmark running on 5.1 based kernel, the total locking rates (in kops/s) on a 2-socket Skylake system with equal numbers of readers and writers (mixed) before and after this patchset were: # of Threads Before Patch After Patch ------------ ------------ ----------- 2 2,618 4,193 4 1,202 3,726 8 802 3,622 16 729 3,359 32 319 2,826 64 102 2,744" The changes are extensive and the patch-set has been through several iterations addressing various locking workloads. There might be more regressions, but unless they are pathological I believe we want to use this new implementation as the baseline going forward. - jump-label optimizations by Daniel Bristot de Oliveira: the primary motivation was to remove IPI disturbance of isolated RT-workload CPUs, which resulted in the implementation of batched jump-label updates. Beyond the improvement of the real-time characteristics kernel, in one test this patchset improved static key update overhead from 57 msecs to just 1.4 msecs - which is a nice speedup as well. - atomic64_t cross-arch type cleanups by Mark Rutland: over the last ~10 years of atomic64_t existence the various types used by the APIs only had to be self-consistent within each architecture - which means they became wildly inconsistent across architectures. Mark puts and end to this by reworking all the atomic64 implementations to use 's64' as the base type for atomic64_t, and to ensure that this type is consistently used for parameters and return values in the API, avoiding further problems in this area. - A large set of small improvements to lockdep by Yuyang Du: type cleanups, output cleanups, function return type and othr cleanups all around the place. - A set of percpu ops cleanups and fixes by Peter Zijlstra. - Misc other changes - please see the Git log for more details" * 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (82 commits) locking/lockdep: increase size of counters for lockdep statistics locking/atomics: Use sed(1) instead of non-standard head(1) option locking/lockdep: Move mark_lock() inside CONFIG_TRACE_IRQFLAGS && CONFIG_PROVE_LOCKING x86/jump_label: Make tp_vec_nr static x86/percpu: Optimize raw_cpu_xchg() x86/percpu, sched/fair: Avoid local_clock() x86/percpu, x86/irq: Relax {set,get}_irq_regs() x86/percpu: Relax smp_processor_id() x86/percpu: Differentiate this_cpu_{}() and __this_cpu_{}() locking/rwsem: Guard against making count negative locking/rwsem: Adaptive disabling of reader optimistic spinning locking/rwsem: Enable time-based spinning on reader-owned rwsem locking/rwsem: Make rwsem->owner an atomic_long_t locking/rwsem: Enable readers spinning on writer locking/rwsem: Clarify usage of owner's nonspinaable bit locking/rwsem: Wake up almost all readers in wait queue locking/rwsem: More optimal RT task handling of null owner locking/rwsem: Always release wait_lock before waking up tasks locking/rwsem: Implement lock handoff to prevent lock starvation locking/rwsem: Make rwsem_spin_on_owner() return owner state ...

smp: Remove smp_call_function() and on_each_cpu() return values

2019-06-23T12:26:26Z

The return value is fixed. Remove it and amend the callers. [ tglx: Fixup arm/bL_switcher and powerpc/rtas ] Signed-off-by: Nadav Amit Signed-off-by: Thomas Gleixner Cc: Peter Zijlstra Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Dave Hansen Cc: Richard Henderson Cc: Ivan Kokshaysky Cc: Matt Turner Cc: Tony Luck Cc: Fenghua Yu Cc: Andrew Morton Link: https://lkml.kernel.org/r/20190613064813.8102-2-namit@vmware.com

x86/percpu: Relax smp_processor_id()

2019-06-17T10:43:41Z

Nadav reported that since this_cpu_read() became asm-volatile, many smp_processor_id() users generated worse code due to the extra constraints. However since smp_processor_id() is reading a stable value, we can use __this_cpu_read(). While this does reduce text size somewhat, this mostly results in code movement to .text.unlikely as a result of more/larger .cold. subfunctions. Less text on the hotpath is good for I$. $ ./compare.sh defconfig-build1 defconfig-build2 vmlinux.o setup_APIC_ibs 90 98 -12,+20 force_ibs_eilvt_setup 400 413 -57,+70 pci_serr_error 109 104 -54,+49 pci_serr_error 109 104 -54,+49 unknown_nmi_error 125 120 -76,+71 unknown_nmi_error 125 120 -76,+71 io_check_error 125 132 -97,+104 intel_thermal_interrupt 730 822 +92,+0 intel_init_thermal 951 945 -6,+0 generic_get_mtrr 301 294 -7,+0 generic_get_mtrr 301 294 -7,+0 generic_set_all 749 754 -44,+49 get_fixed_ranges 352 360 -41,+49 x86_acpi_suspend_lowlevel 369 363 -6,+0 check_tsc_sync_source 412 412 -71,+71 irq_migrate_all_off_this_cpu 662 674 -14,+26 clocksource_watchdog 748 748 -113,+113 __perf_event_account_interrupt 204 197 -7,+0 attempt_merge 1748 1741 -7,+0 intel_guc_send_ct 1424 1409 -15,+0 __fini_doorbell 235 231 -4,+0 bdw_set_cdclk 928 923 -5,+0 gen11_dsi_disable 1571 1556 -15,+0 gmbus_wait 493 488 -5,+0 md_make_request 376 369 -7,+0 __split_and_process_bio 543 536 -7,+0 delay_tsc 96 89 -7,+0 hsw_disable_pc8 696 691 -5,+0 tsc_verify_tsc_adjust 215 228 -22,+35 cpuidle_driver_unref 56 49 -7,+0 blk_account_io_completion 159 148 -11,+0 mtrr_wrmsr 95 99 -29,+33 __intel_wait_for_register_fw 401 419 +18,+0 cpuidle_driver_ref 43 36 -7,+0 cpuidle_get_driver 15 8 -7,+0 blk_account_io_done 535 528 -7,+0 irq_migrate_all_off_this_cpu 662 674 -14,+26 check_tsc_sync_source 412 412 -71,+71 irq_wait_for_poll 170 163 -7,+0 generic_end_io_acct 329 322 -7,+0 x86_acpi_suspend_lowlevel 369 363 -6,+0 nohz_balance_enter_idle 198 191 -7,+0 generic_start_io_acct 254 247 -7,+0 blk_account_io_start 341 334 -7,+0 perf_event_task_tick 682 675 -7,+0 intel_init_thermal 951 945 -6,+0 amd_e400_c1e_apic_setup 47 51 -28,+32 setup_APIC_eilvt 350 328 -22,+0 hsw_enable_pc8 1611 1605 -6,+0 total 12985947 12985892 -994,+939 Reported-by: Nadav Amit Signed-off-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Signed-off-by: Ingo Molnar