[PATCH 0/9] lib/bitmap: optimize bitmap_weight() usage

Yury Norov yury.norov at gmail.com
Sat Nov 27 19:56:55 PST 2021


In many cases people use bitmap_weight()-based functions like this:

	if (num_present_cpus() > 1)
		do_something();

This may take considerable amount of time on many-cpus machines because
num_present_cpus() will traverse every word of underlying cpumask
unconditionally.

We can significantly improve on it for many real cases if stop traversing
the mask as soon as we count present cpus to any number greater than 1:

	if (num_present_cpus_gt(1))
		do_something();

To implement this idea, the series adds bitmap_weight_{eq,gt,le}
functions together with corresponding wrappers in cpumask and nodemask.

Yury Norov (9):
  lib/bitmap: add bitmap_weight_{eq,gt,le}
  lib/bitmap: implement bitmap_{empty,full} with bitmap_weight_eq()
  all: replace bitmap_weigth() with bitmap_{empty,full,eq,gt,le}
  tools: sync bitmap_weight() usage with the kernel
  lib/cpumask: add cpumask_weight_{eq,gt,le}
  lib/nodemask: add nodemask_weight_{eq,gt,le}
  lib/cpumask: add num_{possible,present,active}_cpus_{eq,gt,le}
  lib/nodemask: add num_node_state_eq()
  MAINTAINERS: add cpumask and nodemask files to BITMAP_API

 MAINTAINERS                                   |  4 ++
 arch/alpha/kernel/process.c                   |  2 +-
 arch/arc/kernel/smp.c                         |  2 +-
 arch/arm/kernel/machine_kexec.c               |  2 +-
 arch/arm/mach-exynos/exynos.c                 |  2 +-
 arch/arm/mm/cache-b15-rac.c                   |  2 +-
 arch/arm64/kernel/smp.c                       |  2 +-
 arch/arm64/mm/context.c                       |  2 +-
 arch/csky/mm/asid.c                           |  2 +-
 arch/csky/mm/context.c                        |  2 +-
 arch/ia64/kernel/setup.c                      |  2 +-
 arch/ia64/mm/tlb.c                            |  8 +--
 arch/mips/cavium-octeon/octeon-irq.c          |  4 +-
 arch/mips/kernel/crash.c                      |  2 +-
 arch/mips/kernel/i8253.c                      |  2 +-
 arch/mips/kernel/perf_event_mipsxx.c          |  4 +-
 arch/mips/kernel/rtlx-cmp.c                   |  2 +-
 arch/mips/kernel/smp.c                        |  4 +-
 arch/mips/kernel/vpe-cmp.c                    |  2 +-
 .../loongson2ef/common/cs5536/cs5536_mfgpt.c  |  2 +-
 arch/mips/mm/context.c                        |  2 +-
 arch/mips/mm/tlbex.c                          |  2 +-
 arch/nds32/kernel/perf_event_cpu.c            |  4 +-
 arch/nios2/kernel/cpuinfo.c                   |  2 +-
 arch/powerpc/kernel/smp.c                     |  2 +-
 arch/powerpc/kernel/watchdog.c                |  4 +-
 arch/powerpc/platforms/85xx/smp.c             |  2 +-
 arch/powerpc/platforms/pseries/hotplug-cpu.c  |  4 +-
 arch/powerpc/sysdev/mpic.c                    |  2 +-
 arch/powerpc/xmon/xmon.c                      | 10 +--
 arch/riscv/kvm/vmid.c                         |  2 +-
 arch/s390/kernel/perf_cpum_cf.c               |  2 +-
 arch/sparc/kernel/mdesc.c                     |  6 +-
 arch/x86/events/amd/core.c                    |  2 +-
 arch/x86/kernel/alternative.c                 |  8 +--
 arch/x86/kernel/apic/apic.c                   |  4 +-
 arch/x86/kernel/apic/apic_flat_64.c           |  2 +-
 arch/x86/kernel/apic/probe_32.c               |  2 +-
 arch/x86/kernel/cpu/mce/dev-mcelog.c          |  2 +-
 arch/x86/kernel/cpu/resctrl/rdtgroup.c        | 18 +++---
 arch/x86/kernel/hpet.c                        |  2 +-
 arch/x86/kernel/i8253.c                       |  2 +-
 arch/x86/kernel/kvm.c                         |  2 +-
 arch/x86/kernel/kvmclock.c                    |  2 +-
 arch/x86/kernel/smpboot.c                     |  4 +-
 arch/x86/kernel/tsc.c                         |  2 +-
 arch/x86/kvm/hyperv.c                         |  8 +--
 arch/x86/mm/amdtopology.c                     |  2 +-
 arch/x86/mm/mmio-mod.c                        |  2 +-
 arch/x86/mm/numa_emulation.c                  |  4 +-
 arch/x86/platform/uv/uv_nmi.c                 |  2 +-
 arch/x86/xen/smp_pv.c                         |  2 +-
 arch/x86/xen/spinlock.c                       |  2 +-
 drivers/acpi/numa/srat.c                      |  2 +-
 drivers/clk/samsung/clk-exynos4.c             |  2 +-
 drivers/clocksource/ingenic-timer.c           |  3 +-
 drivers/cpufreq/pcc-cpufreq.c                 |  2 +-
 drivers/cpufreq/qcom-cpufreq-hw.c             |  2 +-
 drivers/cpufreq/scmi-cpufreq.c                |  2 +-
 drivers/crypto/ccp/ccp-dev-v5.c               |  5 +-
 drivers/dma/mv_xor.c                          |  5 +-
 drivers/firmware/psci/psci_checker.c          |  2 +-
 drivers/gpu/drm/i810/i810_drv.c               |  2 +-
 drivers/gpu/drm/i915/i915_pmu.c               |  2 +-
 drivers/gpu/drm/msm/disp/mdp5/mdp5_smp.c      |  2 +-
 drivers/hv/channel_mgmt.c                     |  4 +-
 drivers/iio/adc/mxs-lradc-adc.c               |  3 +-
 drivers/iio/dummy/iio_simple_dummy_buffer.c   |  4 +-
 drivers/iio/industrialio-buffer.c             |  2 +-
 drivers/iio/industrialio-trigger.c            |  2 +-
 drivers/infiniband/hw/hfi1/affinity.c         | 13 ++--
 drivers/infiniband/hw/qib/qib_file_ops.c      |  2 +-
 drivers/infiniband/hw/qib/qib_iba7322.c       |  2 +-
 drivers/infiniband/sw/siw/siw_main.c          |  3 +-
 drivers/irqchip/irq-bcm6345-l1.c              |  2 +-
 drivers/irqchip/irq-gic.c                     |  2 +-
 drivers/memstick/core/ms_block.c              |  4 +-
 drivers/net/caif/caif_virtio.c                |  2 +-
 drivers/net/dsa/b53/b53_common.c              |  2 +-
 drivers/net/ethernet/broadcom/bcmsysport.c    |  6 +-
 .../cavium/liquidio/cn23xx_vf_device.c        |  2 +-
 drivers/net/ethernet/hisilicon/hns/hns_enet.c |  2 +-
 .../net/ethernet/intel/ice/ice_virtchnl_pf.c  |  4 +-
 .../net/ethernet/intel/ixgbe/ixgbe_sriov.c    |  2 +-
 .../net/ethernet/marvell/mvpp2/mvpp2_main.c   |  2 +-
 .../marvell/octeontx2/nic/otx2_ethtool.c      |  2 +-
 .../marvell/octeontx2/nic/otx2_flows.c        |  8 +--
 .../ethernet/marvell/octeontx2/nic/otx2_pf.c  |  2 +-
 drivers/net/ethernet/mellanox/mlx4/cmd.c      | 10 +--
 drivers/net/ethernet/mellanox/mlx4/eq.c       |  4 +-
 drivers/net/ethernet/mellanox/mlx4/main.c     |  2 +-
 .../ethernet/mellanox/mlx5/core/en_ethtool.c  |  2 +-
 drivers/net/ethernet/qlogic/qed/qed_dev.c     |  3 +-
 drivers/net/ethernet/qlogic/qed/qed_rdma.c    |  4 +-
 drivers/net/ethernet/qlogic/qed/qed_roce.c    |  2 +-
 drivers/net/wireless/ath/ath9k/hw.c           |  2 +-
 drivers/net/wireless/marvell/mwifiex/main.c   |  4 +-
 drivers/net/wireless/st/cw1200/queue.c        |  3 +-
 drivers/nvdimm/region.c                       |  2 +-
 drivers/nvme/host/pci.c                       |  2 +-
 drivers/perf/arm-cci.c                        |  2 +-
 drivers/perf/arm_pmu.c                        |  6 +-
 drivers/perf/hisilicon/hisi_uncore_pmu.c      |  2 +-
 drivers/perf/thunderx2_pmu.c                  |  3 +-
 drivers/perf/xgene_pmu.c                      |  2 +-
 .../intel/speed_select_if/isst_if_common.c    |  6 +-
 drivers/pwm/pwm-pca9685.c                     |  2 +-
 drivers/scsi/lpfc/lpfc_init.c                 |  2 +-
 drivers/soc/bcm/brcmstb/biuctrl.c             |  2 +-
 drivers/soc/fsl/dpio/dpio-service.c           |  4 +-
 drivers/soc/fsl/qbman/qman_test_stash.c       |  2 +-
 drivers/spi/spi-dw-bt1.c                      |  2 +-
 drivers/staging/media/tegra-video/vi.c        |  2 +-
 drivers/thermal/intel/intel_powerclamp.c      | 10 ++-
 drivers/virt/acrn/hsm.c                       |  2 +-
 fs/ocfs2/cluster/heartbeat.c                  | 14 ++---
 fs/xfs/xfs_sysfs.c                            |  2 +-
 include/linux/bitmap.h                        | 45 ++++++++++---
 include/linux/cpumask.h                       | 55 ++++++++++++++++
 include/linux/kdb.h                           |  2 +-
 include/linux/nodemask.h                      | 29 +++++++++
 kernel/debug/kdb/kdb_bt.c                     |  2 +-
 kernel/irq/affinity.c                         |  2 +-
 kernel/padata.c                               |  2 +-
 kernel/printk/printk.c                        |  2 +-
 kernel/rcu/tree_nocb.h                        |  4 +-
 kernel/rcu/tree_plugin.h                      |  2 +-
 kernel/reboot.c                               |  4 +-
 kernel/sched/core.c                           | 10 +--
 kernel/sched/topology.c                       |  4 +-
 kernel/time/clockevents.c                     |  4 +-
 kernel/time/clocksource.c                     |  2 +-
 lib/bitmap.c                                  | 63 +++++++++++++++++++
 mm/mempolicy.c                                |  2 +-
 mm/page_alloc.c                               |  2 +-
 mm/percpu.c                                   |  6 +-
 mm/slab.c                                     |  2 +-
 mm/vmstat.c                                   |  4 +-
 tools/include/linux/bitmap.h                  | 42 ++++++++++---
 tools/lib/bitmap.c                            | 60 ++++++++++++++++++
 tools/perf/builtin-c2c.c                      |  4 +-
 tools/perf/util/pmu.c                         |  2 +-
 142 files changed, 490 insertions(+), 251 deletions(-)

-- 
2.25.1




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