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J . Bottomley" , "Martin K . Petersen" Subject: [PATCH 1/4] scsi: replace use of system_unbound_wq with system_dfl_wq Date: Fri, 31 Oct 2025 10:56:40 +0100 Message-ID: <20251031095643.74246-2-marco.crivellari@suse.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251031095643.74246-1-marco.crivellari@suse.com> References: <20251031095643.74246-1-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-Transfer-Encoding: quoted-printable Content-Type: text/plain; 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/scsi/qla2xxx/qla_os.c | 2 +- drivers/scsi/scsi_transport_iscsi.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/scsi/qla2xxx/qla_os.c b/drivers/scsi/qla2xxx/qla_os.c index 5ffd94586652..d48d8671c18a 100644 --- a/drivers/scsi/qla2xxx/qla_os.c +++ b/drivers/scsi/qla2xxx/qla_os.c @@ -5280,7 +5280,7 @@ void qla24xx_sched_upd_fcport(fc_port_t *fcport) qla2x00_set_fcport_disc_state(fcport, DSC_UPD_FCPORT); spin_unlock_irqrestore(&fcport->vha->work_lock, flags); =20 - queue_work(system_unbound_wq, &fcport->reg_work); + queue_work(system_dfl_wq, &fcport->reg_work); } =20 static diff --git a/drivers/scsi/scsi_transport_iscsi.c b/drivers/scsi/scsi_transp= ort_iscsi.c index 743b4c792ceb..ed21c032bbc4 100644 --- a/drivers/scsi/scsi_transport_iscsi.c +++ b/drivers/scsi/scsi_transport_iscsi.c @@ -3961,7 +3961,7 @@ iscsi_if_recv_msg(struct sk_buff *skb, struct nlmsghd= r *nlh, uint32_t *group) list_del_init(&session->sess_list); spin_unlock_irqrestore(&sesslock, flags); =20 - queue_work(system_unbound_wq, &session->destroy_work); + queue_work(system_dfl_wq, &session->destroy_work); } break; case ISCSI_UEVENT_UNBIND_SESSION: --=20 2.51.0 From nobody Sun Feb 8 02:56:32 2026 Received: from mail-wm1-f42.google.com (mail-wm1-f42.google.com [209.85.128.42]) (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 DD6A2333455 for ; Fri, 31 Oct 2025 09:56:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.42 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761904615; cv=none; b=admRw/8ApYXSIjWOazAUlM+vzTCCZhialzTbUWdxY5vv60nSzuGFBPMtSPApeXzibD2p67SPXC5UGm5BaugCy3T1K+rKAjoS/1FsdHfKxdYcMw01/v27UjnptlIJCf3g6IOM17us34ypcSI1LgAh5adBTOHUNWO5REnhDnoqaYo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761904615; c=relaxed/simple; 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Fri, 31 Oct 2025 02:56:52 -0700 (PDT) Received: from localhost.localdomain ([2a00:6d43:105:c401:e307:1a37:2e76:ce91]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4772899fdfbsm81572335e9.4.2025.10.31.02.56.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 31 Oct 2025 02:56:51 -0700 (PDT) From: Marco Crivellari To: linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org Cc: Tejun Heo , Lai Jiangshan , Frederic Weisbecker , Sebastian Andrzej Siewior , Marco Crivellari , Michal Hocko , "James E . J . Bottomley" , "Martin K . Petersen" Subject: [PATCH 2/4] scsi: qla2xxx: WQ_PERCPU added to alloc_workqueue users Date: Fri, 31 Oct 2025 10:56:41 +0100 Message-ID: <20251031095643.74246-3-marco.crivellari@suse.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251031095643.74246-1-marco.crivellari@suse.com> References: <20251031095643.74246-1-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. Suggested-by: Tejun Heo Signed-off-by: Marco Crivellari --- drivers/scsi/qla2xxx/qla_os.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/scsi/qla2xxx/qla_os.c b/drivers/scsi/qla2xxx/qla_os.c index d48d8671c18a..af51f1cf5daa 100644 --- a/drivers/scsi/qla2xxx/qla_os.c +++ b/drivers/scsi/qla2xxx/qla_os.c @@ -3397,7 +3397,7 @@ qla2x00_probe_one(struct pci_dev *pdev, const struct = pci_device_id *id) "req->req_q_in=3D%p req->req_q_out=3D%p rsp->rsp_q_in=3D%p rsp->rsp_q= _out=3D%p.\n", req->req_q_in, req->req_q_out, rsp->rsp_q_in, rsp->rsp_q_out); =20 - ha->wq =3D alloc_workqueue("qla2xxx_wq", WQ_MEM_RECLAIM, 0); + ha->wq =3D alloc_workqueue("qla2xxx_wq", WQ_MEM_RECLAIM | WQ_PERCPU, 0); if (unlikely(!ha->wq)) { ret =3D -ENOMEM; goto probe_failed; --=20 2.51.0 From nobody Sun Feb 8 02:56:32 2026 Received: from mail-wm1-f49.google.com (mail-wm1-f49.google.com [209.85.128.49]) (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 B8E5733373A for ; 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J . Bottomley" , "Martin K . Petersen" Subject: [PATCH 3/4] scsi: scsi_dh_alua: WQ_PERCPU added to alloc_workqueue users Date: Fri, 31 Oct 2025 10:56:42 +0100 Message-ID: <20251031095643.74246-4-marco.crivellari@suse.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251031095643.74246-1-marco.crivellari@suse.com> References: <20251031095643.74246-1-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. Suggested-by: Tejun Heo Signed-off-by: Marco Crivellari --- drivers/scsi/device_handler/scsi_dh_alua.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/devi= ce_handler/scsi_dh_alua.c index 1bf5948d1188..6fd89ae33059 100644 --- a/drivers/scsi/device_handler/scsi_dh_alua.c +++ b/drivers/scsi/device_handler/scsi_dh_alua.c @@ -1300,7 +1300,7 @@ static int __init alua_init(void) { int r; =20 - kaluad_wq =3D alloc_workqueue("kaluad", WQ_MEM_RECLAIM, 0); + kaluad_wq =3D alloc_workqueue("kaluad", WQ_MEM_RECLAIM | WQ_PERCPU, 0); if (!kaluad_wq) return -ENOMEM; =20 --=20 2.51.0 From nobody Sun Feb 8 02:56:32 2026 Received: from mail-wr1-f54.google.com (mail-wr1-f54.google.com [209.85.221.54]) (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 9169D33375B for ; Fri, 31 Oct 2025 09:56:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; 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Fri, 31 Oct 2025 02:56:53 -0700 (PDT) Received: from localhost.localdomain ([2a00:6d43:105:c401:e307:1a37:2e76:ce91]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4772899fdfbsm81572335e9.4.2025.10.31.02.56.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 31 Oct 2025 02:56:53 -0700 (PDT) From: Marco Crivellari To: linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org Cc: Tejun Heo , Lai Jiangshan , Frederic Weisbecker , Sebastian Andrzej Siewior , Marco Crivellari , Michal Hocko , "James E . J . Bottomley" , "Martin K . Petersen" Subject: [PATCH 4/4] scsi: scsi_transport_fc: WQ_PERCPU added to alloc_workqueue users Date: Fri, 31 Oct 2025 10:56:43 +0100 Message-ID: <20251031095643.74246-5-marco.crivellari@suse.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251031095643.74246-1-marco.crivellari@suse.com> References: <20251031095643.74246-1-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. Suggested-by: Tejun Heo Signed-off-by: Marco Crivellari Reviewed-by: Justin Tee --- drivers/scsi/scsi_transport_fc.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/scsi/scsi_transport_fc.c b/drivers/scsi/scsi_transport= _fc.c index 3a821afee9bc..987befb02408 100644 --- a/drivers/scsi/scsi_transport_fc.c +++ b/drivers/scsi/scsi_transport_fc.c @@ -441,7 +441,8 @@ static int fc_host_setup(struct transport_container *tc= , struct device *dev, fc_host->next_vport_number =3D 0; fc_host->npiv_vports_inuse =3D 0; =20 - fc_host->work_q =3D alloc_workqueue("fc_wq_%d", 0, 0, shost->host_no); + fc_host->work_q =3D alloc_workqueue("fc_wq_%d", WQ_PERCPU, 0, + shost->host_no); if (!fc_host->work_q) return -ENOMEM; =20 @@ -3088,7 +3089,7 @@ fc_remote_port_create(struct Scsi_Host *shost, int ch= annel, =20 spin_unlock_irqrestore(shost->host_lock, flags); =20 - rport->devloss_work_q =3D alloc_workqueue("fc_dl_%d_%d", 0, 0, + rport->devloss_work_q =3D alloc_workqueue("fc_dl_%d_%d", WQ_PERCPU, 0, shost->host_no, rport->number); if (!rport->devloss_work_q) { printk(KERN_ERR "FC Remote Port alloc_workqueue failed\n"); --=20 2.51.0