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charset="utf-8" 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 consistency cannot be addressed without refactoring the API. system_unbound_wq should be the default workqueue so as not to enforce locality constraints for random work whenever it's not required. Adding system_dfl_wq to encourage its use when unbound work should be used. The old system_unbound_wq will be kept for a few release cycles. Suggested-by: Tejun Heo Signed-off-by: Marco Crivellari --- drivers/infiniband/core/ucma.c | 2 +- drivers/infiniband/hw/mlx5/odp.c | 4 ++-- 2 files changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c index f86ece701db6..ec3be65a2b88 100644 --- a/drivers/infiniband/core/ucma.c +++ b/drivers/infiniband/core/ucma.c @@ -366,7 +366,7 @@ static int ucma_event_handler(struct rdma_cm_id *cm_id, if (event->event =3D=3D RDMA_CM_EVENT_DEVICE_REMOVAL) { xa_lock(&ctx_table); if (xa_load(&ctx_table, ctx->id) =3D=3D ctx) - queue_work(system_unbound_wq, &ctx->close_work); + queue_work(system_dfl_wq, &ctx->close_work); xa_unlock(&ctx_table); } return 0; diff --git a/drivers/infiniband/hw/mlx5/odp.c b/drivers/infiniband/hw/mlx5/= odp.c index 0e8ae85af5a6..6441abdf1f3b 100644 --- a/drivers/infiniband/hw/mlx5/odp.c +++ b/drivers/infiniband/hw/mlx5/odp.c @@ -265,7 +265,7 @@ static void destroy_unused_implicit_child_mr(struct mlx= 5_ib_mr *mr) =20 /* Freeing a MR is a sleeping operation, so bounce to a work queue */ INIT_WORK(&mr->odp_destroy.work, free_implicit_child_mr_work); 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charset="utf-8" Content-Transfer-Encoding: quoted-printable 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=E2=80=99re needed= and reducing noise when CPUs are isolated. This change adds a new WQ_PERCPU flag to explicitly request alloc_workqueue() to be per-cpu when WQ_UNBOUND has not been specified. With the introduction of the WQ_PERCPU flag (equivalent to !WQ_UNBOUND), any alloc_workqueue() caller that doesn=E2=80=99t explicitly specify WQ_UNB= OUND must now use WQ_PERCPU. Once migration is complete, WQ_UNBOUND can be removed and unbound will become the implicit default. Suggested-by: Tejun Heo Signed-off-by: Marco Crivellari --- drivers/infiniband/core/cm.c | 2 +- drivers/infiniband/core/device.c | 4 ++-- 2 files changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/infiniband/core/cm.c b/drivers/infiniband/core/cm.c index 01bede8ba105..47d0022cadac 100644 --- a/drivers/infiniband/core/cm.c +++ b/drivers/infiniband/core/cm.c @@ -4518,7 +4518,7 @@ static int __init ib_cm_init(void) get_random_bytes(&cm.random_id_operand, sizeof cm.random_id_operand); INIT_LIST_HEAD(&cm.timewait_list); =20 - cm.wq =3D alloc_workqueue("ib_cm", 0, 1); + cm.wq =3D alloc_workqueue("ib_cm", WQ_PERCPU, 1); if (!cm.wq) { ret =3D -ENOMEM; goto error2; diff --git a/drivers/infiniband/core/device.c b/drivers/infiniband/core/dev= ice.c index b4f3c835844a..13e8a1714bbd 100644 --- a/drivers/infiniband/core/device.c +++ b/drivers/infiniband/core/device.c @@ -3021,7 +3021,7 @@ static int __init ib_core_init(void) { int ret =3D -ENOMEM; =20 - ib_wq =3D alloc_workqueue("infiniband", 0, 0); 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charset="utf-8" Content-Transfer-Encoding: quoted-printable 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=E2=80=99re needed= and reducing noise when CPUs are isolated. This change adds a new WQ_PERCPU flag to explicitly request alloc_workqueue() to be per-cpu when WQ_UNBOUND has not been specified. With the introduction of the WQ_PERCPU flag (equivalent to !WQ_UNBOUND), any alloc_workqueue() caller that doesn=E2=80=99t explicitly specify WQ_UNB= OUND must now use WQ_PERCPU. Once migration is complete, WQ_UNBOUND can be removed and unbound will become the implicit default. CC: Dennis Dalessandro Suggested-by: Tejun Heo Signed-off-by: Marco Crivellari --- drivers/infiniband/hw/hfi1/init.c | 4 ++-- drivers/infiniband/hw/hfi1/opfn.c | 4 ++-- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/infiniband/hw/hfi1/init.c b/drivers/infiniband/hw/hfi1= /init.c index b35f92e7d865..e4aef102dac0 100644 --- a/drivers/infiniband/hw/hfi1/init.c +++ b/drivers/infiniband/hw/hfi1/init.c @@ -745,8 +745,8 @@ static int create_workqueues(struct hfi1_devdata *dd) ppd->hfi1_wq =3D alloc_workqueue( "hfi%d_%d", - WQ_SYSFS | WQ_HIGHPRI | WQ_CPU_INTENSIVE | - WQ_MEM_RECLAIM, + WQ_SYSFS | WQ_HIGHPRI | WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM | + WQ_PERCPU, HFI1_MAX_ACTIVE_WORKQUEUE_ENTRIES, dd->unit, pidx); if (!ppd->hfi1_wq) diff --git a/drivers/infiniband/hw/hfi1/opfn.c b/drivers/infiniband/hw/hfi1= /opfn.c index 370a5a8eaa71..6e0e3458d202 100644 --- a/drivers/infiniband/hw/hfi1/opfn.c +++ b/drivers/infiniband/hw/hfi1/opfn.c @@ -305,8 +305,8 @@ void opfn_trigger_conn_request(struct rvt_qp *qp, u32 b= th1) int opfn_init(void) { opfn_wq =3D alloc_workqueue("hfi_opfn", - WQ_SYSFS | WQ_HIGHPRI | WQ_CPU_INTENSIVE | - WQ_MEM_RECLAIM, + WQ_SYSFS | WQ_HIGHPRI | WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM | + WQ_PERCPU, HFI1_MAX_ACTIVE_WORKQUEUE_ENTRIES); 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charset="utf-8" Content-Transfer-Encoding: quoted-printable 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=E2=80=99re needed= and reducing noise when CPUs are isolated. This change adds a new WQ_PERCPU flag to explicitly request alloc_workqueue() to be per-cpu when WQ_UNBOUND has not been specified. With the introduction of the WQ_PERCPU flag (equivalent to !WQ_UNBOUND), any alloc_workqueue() caller that doesn=E2=80=99t explicitly specify WQ_UNB= OUND must now use WQ_PERCPU. Once migration is complete, WQ_UNBOUND can be removed and unbound will become the implicit default. CC: Yishai Hadas Suggested-by: Tejun Heo Signed-off-by: Marco Crivellari --- drivers/infiniband/hw/mlx4/cm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/infiniband/hw/mlx4/cm.c b/drivers/infiniband/hw/mlx4/c= m.c index 12b481d138cf..03aacd526860 100644 --- a/drivers/infiniband/hw/mlx4/cm.c +++ b/drivers/infiniband/hw/mlx4/cm.c @@ -591,7 +591,7 @@ void mlx4_ib_cm_paravirt_clean(struct mlx4_ib_dev *dev,= int slave) =20 int mlx4_ib_cm_init(void) { - cm_wq =3D alloc_workqueue("mlx4_ib_cm", 0, 0); + cm_wq =3D alloc_workqueue("mlx4_ib_cm", WQ_PERCPU, 0); if (!cm_wq) return -ENOMEM; =20 --=20 2.51.0 From nobody Sun Feb 8 14:35:30 2026 Received: from mail-wm1-f51.google.com (mail-wm1-f51.google.com [209.85.128.51]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CF432265CDD for ; Sat, 1 Nov 2025 16:31:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; 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Sat, 01 Nov 2025 09:31:44 -0700 (PDT) Received: from localhost.localdomain ([2a00:6d43:105:c401:e307:1a37:2e76:ce91]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4773c394e33sm56742285e9.13.2025.11.01.09.31.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 01 Nov 2025 09:31:44 -0700 (PDT) From: Marco Crivellari To: linux-kernel@vger.kernel.org, linux-rdma@vger.kernel.org Cc: Tejun Heo , Lai Jiangshan , Frederic Weisbecker , Sebastian Andrzej Siewior , Marco Crivellari , Michal Hocko , Jason Gunthorpe , Leon Romanovsky , Dennis Dalessandro Subject: [PATCH 5/5] IB/rdmavt: WQ_PERCPU added to alloc_workqueue users Date: Sat, 1 Nov 2025 17:31:15 +0100 Message-ID: <20251101163121.78400-6-marco.crivellari@suse.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251101163121.78400-1-marco.crivellari@suse.com> References: <20251101163121.78400-1-marco.crivellari@suse.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable 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=E2=80=99re needed= and reducing noise when CPUs are isolated. This change adds a new WQ_PERCPU flag to explicitly request alloc_workqueue() to be per-cpu when WQ_UNBOUND has not been specified. With the introduction of the WQ_PERCPU flag (equivalent to !WQ_UNBOUND), any alloc_workqueue() caller that doesn=E2=80=99t explicitly specify WQ_UNB= OUND must now use WQ_PERCPU. Once migration is complete, WQ_UNBOUND can be removed and unbound will become the implicit default. CC: Dennis Dalessandro Suggested-by: Tejun Heo Signed-off-by: Marco Crivellari --- drivers/infiniband/sw/rdmavt/cq.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/infiniband/sw/rdmavt/cq.c b/drivers/infiniband/sw/rdma= vt/cq.c index 0ca2743f1075..e7835ca70e2b 100644 --- a/drivers/infiniband/sw/rdmavt/cq.c +++ b/drivers/infiniband/sw/rdmavt/cq.c @@ -518,7 +518,8 @@ int rvt_poll_cq(struct ib_cq *ibcq, int num_entries, st= ruct ib_wc *entry) */ int rvt_driver_cq_init(void) { - comp_vector_wq =3D alloc_workqueue("%s", WQ_HIGHPRI | WQ_CPU_INTENSIVE, + comp_vector_wq =3D alloc_workqueue("%s", + WQ_HIGHPRI | WQ_CPU_INTENSIVE | WQ_PERCPU, 0, "rdmavt_cq"); if (!comp_vector_wq) return -ENOMEM; --=20 2.51.0