From: Frederic Weisbecker <frederic@kernel.org>
To: Marco Crivellari <marco.crivellari@suse.com>
Cc: linux-kernel@vger.kernel.org, Tejun Heo <tj@kernel.org>,
Lai Jiangshan <jiangshanlai@gmail.com>,
Thomas Gleixner <tglx@linutronix.de>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Michal Hocko <mhocko@suse.com>
Subject: Re: [PATCH v2 3/4] Workqueue: WQ_PERCPU added to all the remaining users
Date: Mon, 25 Aug 2025 15:55:00 +0200 [thread overview]
Message-ID: <aKxrNPfjjACwqSAa@localhost.localdomain> (raw)
In-Reply-To: <20250825132906.1050437-4-marco.crivellari@suse.com>
Le Mon, Aug 25, 2025 at 03:29:05PM +0200, Marco Crivellari a écrit :
> Currently if a user enqueue a work item using schedule_delayed_work() the
> used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use
> WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to
> schedule_work() that is using system_wq and queue_work(), that makes use
> again of WORK_CPU_UNBOUND.
> This lack of consistentcy cannot be addressed without refactoring the API.
>
> alloc_workqueue() treats all queues as per-CPU by default, while unbound
> workqueues must opt-in via WQ_UNBOUND.
>
> This default is suboptimal: most workloads benefit from unbound queues,
> allowing the scheduler to place worker threads where they’re needed and
> reducing noise when CPUs are isolated.
>
> This default is suboptimal: most workloads benefit from unbound queues,
> allowing the scheduler to place worker threads where they’re needed and
> reducing noise when CPUs are isolated.
>
> This patch adds a new WQ_PERCPU flag to explicitly request the use of
> the per-CPU behavior. Both flags coexist for one release cycle to allow
> callers to transition their calls.
>
> Once migration is complete, WQ_UNBOUND can be removed and unbound will
> become the implicit default.
>
> With the introduction of the WQ_PERCPU flag (equivalent to !WQ_UNBOUND),
> any alloc_workqueue() caller that doesn’t explicitly specify WQ_UNBOUND
> must now use WQ_PERCPU.
>
> All existing users have been updated accordingly.
>
> Suggested-by: Tejun Heo <tj@kernel.org>
> Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>
A similar per subsystem patch cut should be done here.
> ---
> block/bio-integrity-auto.c | 5 +++--
> block/bio.c | 3 ++-
> block/blk-core.c | 3 ++-
> block/blk-throttle.c | 3 ++-
> block/blk-zoned.c | 3 ++-
One for block.
> crypto/cryptd.c | 3 ++-
One for crypto API.
> drivers/acpi/ec.c | 3 ++-
> drivers/acpi/osl.c | 4 ++--
> drivers/acpi/thermal.c | 3 ++-
> drivers/ata/libata-sff.c | 3 ++-
> drivers/base/core.c | 2 +-
> drivers/block/aoe/aoemain.c | 2 +-
> drivers/block/rbd.c | 2 +-
> drivers/block/rnbd/rnbd-clt.c | 2 +-
> drivers/block/sunvdc.c | 2 +-
> drivers/block/virtio_blk.c | 2 +-
> drivers/bus/mhi/ep/main.c | 2 +-
> drivers/char/tpm/tpm-dev-common.c | 3 ++-
> drivers/char/xillybus/xillybus_core.c | 2 +-
> drivers/char/xillybus/xillyusb.c | 4 ++--
> drivers/cpufreq/tegra194-cpufreq.c | 3 ++-
> drivers/crypto/atmel-i2c.c | 2 +-
> drivers/crypto/cavium/nitrox/nitrox_mbx.c | 2 +-
> drivers/crypto/intel/qat/qat_common/adf_aer.c | 4 ++--
> drivers/crypto/intel/qat/qat_common/adf_isr.c | 3 ++-
> .../crypto/intel/qat/qat_common/adf_sriov.c | 3 ++-
> .../crypto/intel/qat/qat_common/adf_vf_isr.c | 3 ++-
> drivers/firewire/core-transaction.c | 3 ++-
> drivers/firewire/ohci.c | 3 ++-
> drivers/gpu/drm/amd/amdkfd/kfd_process.c | 3 ++-
> drivers/gpu/drm/bridge/analogix/anx7625.c | 3 ++-
> .../drm/i915/display/intel_display_driver.c | 3 ++-
> drivers/gpu/drm/i915/i915_driver.c | 3 ++-
> .../gpu/drm/i915/selftests/i915_sw_fence.c | 2 +-
> .../gpu/drm/i915/selftests/mock_gem_device.c | 2 +-
> drivers/gpu/drm/nouveau/nouveau_drm.c | 2 +-
> drivers/gpu/drm/nouveau/nouveau_sched.c | 3 ++-
> drivers/gpu/drm/radeon/radeon_display.c | 3 ++-
> drivers/gpu/drm/xe/xe_device.c | 4 ++--
> drivers/gpu/drm/xe/xe_ggtt.c | 2 +-
> drivers/gpu/drm/xe/xe_hw_engine_group.c | 3 ++-
> drivers/gpu/drm/xe/xe_sriov.c | 2 +-
> drivers/greybus/operation.c | 2 +-
> drivers/hid/hid-nintendo.c | 3 ++-
> drivers/hv/mshv_eventfd.c | 2 +-
> drivers/i3c/master.c | 2 +-
> drivers/infiniband/core/cm.c | 2 +-
> drivers/infiniband/core/device.c | 4 ++--
> drivers/infiniband/hw/hfi1/init.c | 3 +--
> drivers/infiniband/hw/hfi1/opfn.c | 3 +--
> drivers/infiniband/hw/mlx4/cm.c | 2 +-
> drivers/infiniband/sw/rdmavt/cq.c | 3 ++-
> drivers/infiniband/ulp/iser/iscsi_iser.c | 2 +-
> drivers/infiniband/ulp/isert/ib_isert.c | 2 +-
> drivers/infiniband/ulp/rtrs/rtrs-clt.c | 2 +-
> drivers/infiniband/ulp/rtrs/rtrs-srv.c | 2 +-
> drivers/input/mouse/psmouse-smbus.c | 2 +-
> drivers/isdn/capi/kcapi.c | 2 +-
> drivers/md/bcache/btree.c | 3 ++-
> drivers/md/bcache/super.c | 10 ++++++----
> drivers/md/bcache/writeback.c | 2 +-
> drivers/md/dm-bufio.c | 3 ++-
> drivers/md/dm-cache-target.c | 3 ++-
> drivers/md/dm-clone-target.c | 3 ++-
> drivers/md/dm-crypt.c | 6 ++++--
> drivers/md/dm-delay.c | 4 +++-
> drivers/md/dm-integrity.c | 15 ++++++++++-----
> drivers/md/dm-kcopyd.c | 3 ++-
> drivers/md/dm-log-userspace-base.c | 3 ++-
> drivers/md/dm-mpath.c | 5 +++--
> drivers/md/dm-raid1.c | 5 +++--
> drivers/md/dm-snap-persistent.c | 3 ++-
> drivers/md/dm-stripe.c | 2 +-
> drivers/md/dm-verity-target.c | 4 +++-
> drivers/md/dm-writecache.c | 3 ++-
> drivers/md/dm.c | 3 ++-
> drivers/md/md.c | 4 ++--
> drivers/media/pci/ddbridge/ddbridge-core.c | 2 +-
> .../platform/mediatek/mdp3/mtk-mdp3-core.c | 6 ++++--
> drivers/message/fusion/mptbase.c | 7 +++++--
> drivers/mmc/core/block.c | 3 ++-
> drivers/mmc/host/omap.c | 2 +-
> drivers/net/can/spi/hi311x.c | 3 ++-
> drivers/net/can/spi/mcp251x.c | 3 ++-
> .../net/ethernet/cavium/liquidio/lio_core.c | 2 +-
> .../net/ethernet/cavium/liquidio/lio_main.c | 8 +++++---
> .../ethernet/cavium/liquidio/lio_vf_main.c | 3 ++-
> .../cavium/liquidio/request_manager.c | 2 +-
> .../cavium/liquidio/response_manager.c | 3 ++-
> .../net/ethernet/freescale/dpaa2/dpaa2-eth.c | 2 +-
> .../hisilicon/hns3/hns3pf/hclge_main.c | 3 ++-
> drivers/net/ethernet/intel/fm10k/fm10k_main.c | 2 +-
> drivers/net/ethernet/intel/i40e/i40e_main.c | 2 +-
> .../net/ethernet/marvell/octeontx2/af/cgx.c | 2 +-
> .../marvell/octeontx2/af/mcs_rvu_if.c | 2 +-
> .../ethernet/marvell/octeontx2/af/rvu_cgx.c | 2 +-
> .../ethernet/marvell/octeontx2/af/rvu_rep.c | 2 +-
> .../marvell/octeontx2/nic/cn10k_ipsec.c | 3 ++-
> .../ethernet/marvell/prestera/prestera_main.c | 2 +-
> .../ethernet/marvell/prestera/prestera_pci.c | 2 +-
> drivers/net/ethernet/mellanox/mlxsw/core.c | 4 ++--
> drivers/net/ethernet/netronome/nfp/nfp_main.c | 2 +-
> drivers/net/ethernet/qlogic/qed/qed_main.c | 3 ++-
> drivers/net/ethernet/wiznet/w5100.c | 2 +-
> drivers/net/fjes/fjes_main.c | 5 +++--
> drivers/net/wireguard/device.c | 6 ++++--
> drivers/net/wireless/ath/ath6kl/usb.c | 2 +-
> .../net/wireless/marvell/libertas/if_sdio.c | 3 ++-
> .../net/wireless/marvell/libertas/if_spi.c | 3 ++-
> .../net/wireless/marvell/libertas_tf/main.c | 2 +-
> drivers/net/wireless/quantenna/qtnfmac/core.c | 3 ++-
> drivers/net/wireless/realtek/rtlwifi/base.c | 2 +-
> drivers/net/wireless/realtek/rtw88/usb.c | 3 ++-
> drivers/net/wireless/silabs/wfx/main.c | 2 +-
> drivers/net/wireless/st/cw1200/bh.c | 4 ++--
> drivers/net/wwan/t7xx/t7xx_hif_dpmaif_rx.c | 3 ++-
> drivers/net/wwan/wwan_hwsim.c | 2 +-
> drivers/nvme/host/tcp.c | 2 ++
> drivers/nvme/target/core.c | 5 +++--
> drivers/nvme/target/fc.c | 6 +++---
> drivers/nvme/target/tcp.c | 2 +-
> drivers/pci/endpoint/functions/pci-epf-mhi.c | 2 +-
> drivers/pci/endpoint/functions/pci-epf-ntb.c | 5 +++--
> drivers/pci/endpoint/functions/pci-epf-test.c | 3 ++-
> drivers/pci/endpoint/functions/pci-epf-vntb.c | 5 +++--
> drivers/pci/hotplug/pnv_php.c | 3 ++-
> drivers/pci/hotplug/shpchp_core.c | 3 ++-
> .../platform/surface/surface_acpi_notify.c | 2 +-
> drivers/power/supply/ab8500_btemp.c | 3 ++-
> drivers/power/supply/ipaq_micro_battery.c | 3 ++-
> drivers/rapidio/rio.c | 2 +-
> drivers/s390/char/tape_3590.c | 2 +-
> drivers/scsi/be2iscsi/be_main.c | 3 ++-
> drivers/scsi/bnx2fc/bnx2fc_fcoe.c | 2 +-
> drivers/scsi/device_handler/scsi_dh_alua.c | 2 +-
> drivers/scsi/fcoe/fcoe.c | 2 +-
> drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c | 3 ++-
> drivers/scsi/lpfc/lpfc_init.c | 2 +-
> drivers/scsi/pm8001/pm8001_init.c | 2 +-
> drivers/scsi/qedf/qedf_main.c | 15 ++++++++++-----
> drivers/scsi/qedi/qedi_main.c | 2 +-
> drivers/scsi/qla2xxx/qla_os.c | 2 +-
> drivers/scsi/qla2xxx/qla_target.c | 2 +-
> drivers/scsi/qla2xxx/tcm_qla2xxx.c | 2 +-
> drivers/scsi/qla4xxx/ql4_os.c | 3 ++-
> drivers/scsi/scsi_transport_fc.c | 7 ++++---
> drivers/soc/fsl/qbman/qman.c | 2 +-
> drivers/staging/greybus/sdio.c | 2 +-
> drivers/target/target_core_transport.c | 4 ++--
> drivers/target/target_core_xcopy.c | 2 +-
> drivers/target/tcm_fc/tfc_conf.c | 2 +-
> drivers/usb/core/hub.c | 2 +-
> drivers/usb/gadget/function/f_hid.c | 3 +--
> drivers/usb/storage/uas.c | 2 +-
> drivers/usb/typec/anx7411.c | 3 +--
> drivers/vdpa/vdpa_user/vduse_dev.c | 3 ++-
> drivers/virt/acrn/irqfd.c | 3 ++-
> drivers/virtio/virtio_balloon.c | 3 ++-
> drivers/xen/privcmd.c | 3 ++-
One for drivers.
> include/linux/workqueue.h | 4 ++--
One for workqueue.
> kernel/bpf/cgroup.c | 3 ++-
One for BPF.
> kernel/cgroup/cgroup-v1.c | 2 +-
> kernel/cgroup/cgroup.c | 2 +-
One for cgroup.
> kernel/padata.c | 5 +++--
One for padata.
> kernel/power/main.c | 2 +-
One for power.
> kernel/rcu/tree.c | 4 ++--
One for RCU.
> kernel/workqueue.c | 19 ++++++++++---------
Join the workqueue change above.
> virt/kvm/eventfd.c | 2 +-
And one for KVM.
Thanks.
--
Frederic Weisbecker
SUSE Labs
next prev parent reply other threads:[~2025-08-25 13:55 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-08-25 13:29 [PATCH v2 0/4] Workqueue: replace system wq and change alloc_workqueue callers Marco Crivellari
2025-08-25 13:29 ` [PATCH v2 1/4] Workqueue: replace use of system_wq with system_percpu_wq Marco Crivellari
2025-08-25 13:55 ` Frederic Weisbecker
2025-08-25 13:29 ` [PATCH v2 2/4] Workqueue: replace use of system_unbound_wq with system_dfl_wq Marco Crivellari
2025-08-25 13:49 ` Frederic Weisbecker
2025-08-25 13:29 ` [PATCH v2 3/4] Workqueue: WQ_PERCPU added to all the remaining users Marco Crivellari
2025-08-25 13:55 ` Frederic Weisbecker [this message]
2025-08-25 13:29 ` [PATCH v2 4/4] [Doc] Workqueue: WQ_UNBOUND doc upgraded Marco Crivellari
2025-08-25 13:57 ` Frederic Weisbecker
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