From patchwork Wed Mar 23 14:55:59 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Rasmus Villemoes X-Patchwork-Id: 553837 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A06BCC433EF for ; Wed, 23 Mar 2022 14:56:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244929AbiCWO5k (ORCPT ); Wed, 23 Mar 2022 10:57:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58596 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244940AbiCWO5i (ORCPT ); Wed, 23 Mar 2022 10:57:38 -0400 Received: from mail-ej1-x629.google.com (mail-ej1-x629.google.com [IPv6:2a00:1450:4864:20::629]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2A4CF81658 for ; Wed, 23 Mar 2022 07:56:09 -0700 (PDT) Received: by mail-ej1-x629.google.com with SMTP id bi12so3393020ejb.3 for ; Wed, 23 Mar 2022 07:56:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rasmusvillemoes.dk; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=4ocZ020biSSlMCzLyHzrYyXSRMNycQFiAPnqhwZV8Jo=; b=ToXuI8M/+8sDxN7w3MxP2P8OJelARc/TEu7LTms49PxLD3X8ufyrk6AZFIJYptu97f t718JP97xCJnh5iU+PKgahb5HYzvQaNodRYaspB53ZW5Szp69qqAYj5u1/WAlEmTky3J pu0TJ4VcwtC4yHyk7FCC2Jj0NseTlZevPA7RQ= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=4ocZ020biSSlMCzLyHzrYyXSRMNycQFiAPnqhwZV8Jo=; b=wKnx9ZmSsvzuRlOLWdWQe2jJ+blfcc0TCTQEPmcc7+kKFyEI+0GoWS02j5b75Z+qQI MzgSCoMCdgWCa72dQEPRLdzBWUk/mz40UORkDkciBPtUyaN0eu4vNkbjclifxfHlEgTp ZPFZo5GfTPm6cd0n16FT50ndVM498qsPKxh6TBVsLa+Hhv49mb4T68Za5f5KbF2DqpLO K3gRoqIl9qHFY9yIdCllZWrlw6ezbuYSuDHof3CdUVXTyppXh3WHBsxQ/LM3DHf1Ye1n /uEGMcJiHJdW9LlNdrHfd/ZTQ8ezEFe7NhvxQBtwtCK0to8/7sS+BSLZIZEPRV1Aa+NM gL8Q== X-Gm-Message-State: AOAM533T7xX0Fu31jmO3c6VlUG96zDxFHU9TiLQW2fbz9Un1fbWLnb+Q ShCM5sNtDcK4e43pXqbFtXQSxg== X-Google-Smtp-Source: ABdhPJxCumSHokPvg0VDPchzYbIyB8Shhfo0ruu/8TYZEwJYtl/jJX8JvRe7KF4Av1voNThfaQcD5A== X-Received: by 2002:a17:907:2d13:b0:6df:a061:8141 with SMTP id gs19-20020a1709072d1300b006dfa0618141mr325151ejc.663.1648047367675; Wed, 23 Mar 2022 07:56:07 -0700 (PDT) Received: from prevas-ravi.tritech.se ([80.208.64.233]) by smtp.gmail.com with ESMTPSA id p14-20020a05640210ce00b00413211746d4sm77256edu.51.2022.03.23.07.56.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 23 Mar 2022 07:56:06 -0700 (PDT) From: Rasmus Villemoes To: Tejun Heo , Lai Jiangshan Cc: =?utf-8?q?Andr=C3=A9_Pribil?= , Steven Walter , Oleksij Rempel , Esben Haabendal , Jiri Slaby , Pengutronix Kernel Team , Peter Hurley , linux-rt-users@vger.kernel.org, Rasmus Villemoes , linux-kernel@vger.kernel.org Subject: [RFC PATCH 1/2] workqueue: allow use of realtime scheduling policies Date: Wed, 23 Mar 2022 15:55:59 +0100 Message-Id: <20220323145600.2156689-2-linux@rasmusvillemoes.dk> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20220323145600.2156689-1-linux@rasmusvillemoes.dk> References: <20220323145600.2156689-1-linux@rasmusvillemoes.dk> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-rt-users@vger.kernel.org Prepare for allowing the administrator to set RT scheduling policies, rather than just tweaking the nice value, of workqueues exposed via sysfs. Subsystems that currently use, say, system_unbound_wq, can be updated to create a separate workqueue (possibly depending on a CONFIG_ knob or boottime parameter). This patch merely updates the internal interfaces. The next patch will expose a sysfs knob. Signed-off-by: Rasmus Villemoes --- include/linux/workqueue.h | 17 +++++++++++++++-- kernel/workqueue.c | 20 ++++++++++++++++++-- 2 files changed, 33 insertions(+), 4 deletions(-) diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h index 7fee9b6cfede..a69bdd877120 100644 --- a/include/linux/workqueue.h +++ b/include/linux/workqueue.h @@ -131,9 +131,22 @@ struct rcu_work { */ struct workqueue_attrs { /** - * @nice: nice level + * @policy: scheduling policy (SCHED_NORMAL, SCHED_FIFO, SCHED_RR) */ - int nice; + int policy; + + /** + * @nice: nice level (SCHED_NORMAL) + * @priority: priority (SCHED_FIFO, SCHED_RR) + * + * Letting these two fields occupy the same word simplifies + * copying, hashing and equality testing of struct + * workqueue_attrs. + */ + union { + int nice; + int priority; + }; /** * @cpumask: allowed CPUs diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 33f1106b4f99..9eb2ff7bcc04 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -51,6 +51,7 @@ #include #include #include +#include #include "workqueue_internal.h" @@ -1969,7 +1970,13 @@ static struct worker *create_worker(struct worker_pool *pool) if (IS_ERR(worker->task)) goto fail; - set_user_nice(worker->task, pool->attrs->nice); + if (pool->attrs->policy == SCHED_NORMAL) { + set_user_nice(worker->task, pool->attrs->nice); + } else { + struct sched_param sp = { .sched_priority = pool->attrs->priority }; + + sched_setscheduler(worker->task, pool->attrs->policy, &sp); + } kthread_bind_mask(worker->task, pool->attrs->cpumask); /* successful, attach the worker to the pool */ @@ -3402,6 +3409,12 @@ struct workqueue_attrs *alloc_workqueue_attrs(void) { struct workqueue_attrs *attrs; + /* + * A zeroed structure has ->policy==SCHED_NORMAL and + * ->nice==0. + */ + static_assert(SCHED_NORMAL == 0); + attrs = kzalloc(sizeof(*attrs), GFP_KERNEL); if (!attrs) goto fail; @@ -3418,6 +3431,7 @@ struct workqueue_attrs *alloc_workqueue_attrs(void) static void copy_workqueue_attrs(struct workqueue_attrs *to, const struct workqueue_attrs *from) { + to->policy = from->policy; to->nice = from->nice; cpumask_copy(to->cpumask, from->cpumask); /* @@ -3433,7 +3447,7 @@ static u32 wqattrs_hash(const struct workqueue_attrs *attrs) { u32 hash = 0; - hash = jhash_1word(attrs->nice, hash); + hash = jhash_2words(attrs->policy, attrs->nice, hash); hash = jhash(cpumask_bits(attrs->cpumask), BITS_TO_LONGS(nr_cpumask_bits) * sizeof(long), hash); return hash; @@ -3443,6 +3457,8 @@ static u32 wqattrs_hash(const struct workqueue_attrs *attrs) static bool wqattrs_equal(const struct workqueue_attrs *a, const struct workqueue_attrs *b) { + if (a->policy != b->policy) + return false; if (a->nice != b->nice) return false; if (!cpumask_equal(a->cpumask, b->cpumask)) From patchwork Wed Mar 23 14:56:00 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Rasmus Villemoes X-Patchwork-Id: 553990 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 28568C433EF for ; Wed, 23 Mar 2022 14:56:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244941AbiCWO5o (ORCPT ); Wed, 23 Mar 2022 10:57:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58626 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244934AbiCWO5k (ORCPT ); Wed, 23 Mar 2022 10:57:40 -0400 Received: from mail-ej1-x632.google.com (mail-ej1-x632.google.com [IPv6:2a00:1450:4864:20::632]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8AFCC7DE24 for ; Wed, 23 Mar 2022 07:56:10 -0700 (PDT) Received: by mail-ej1-x632.google.com with SMTP id yy13so3392791ejb.2 for ; Wed, 23 Mar 2022 07:56:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rasmusvillemoes.dk; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=xxpZ0iiJJ0ZwZEvYkcJ55MAH2/mjQ7Nkl8lEGJi9pe8=; b=LABB1GCxIPlD3luxLyc/Nvl+Hx/y317qPwHAgq23XvnHF9qpUBg7Oj4qKR9m2oKy9Z nLHPjFsSVxbqnfMNTml3G5XFtYhv8f8ntalWyDLPzFpp/dHrB+gFda+AuFQOaMhvDpOG lVJ8tx+kfAFLsN1d7jnDqXAnP4HnCw5VLTupQ= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=xxpZ0iiJJ0ZwZEvYkcJ55MAH2/mjQ7Nkl8lEGJi9pe8=; b=H0059s8Lvyf49ajyGUvnMWhWP+EcS/8v0C+Wcn4EW68JG8NuN5q2gYrQJt8DPaCo3j dYnF3tfMfxxKT28SDGlVVjYtM219YPZLF4VFatFoBh/eYwS9Af9KHnnTOtJEKhIMtUI4 baaHJ4uKmZXz3vOuPVk8W0afubq7RTP5SruLY6OJT6aEmNCaF0rpBqTWABzJJ2rPf6Bc PIvb9oCesq1oe2RuLego18poaiujgiOyDtLwUvZrjlZKzIriP862vtWHs+H/6iLvjgn4 uUXhi9+YEMV7hCxhG4ls6fmgGvs8RI0fRxa42Hjq8Uq1ZcAm9e5tvNLz1INVJgDfq9k5 u3aQ== X-Gm-Message-State: AOAM530rAsfE1H3cJs+cxvhL4TjGgs2MH7rPEmFCwnjwXhziyrWGQ5k7 X2oIiN3o22by3kts14VPHAxbGQ== X-Google-Smtp-Source: ABdhPJyFFyzCsMB02alxju10p2mtcDMblMiJlaXPaFNhnOhkRjAQ/fDW1gf6qTgwYf+nZz7WQmnLzQ== X-Received: by 2002:a17:906:57c1:b0:6d6:da73:e9c0 with SMTP id u1-20020a17090657c100b006d6da73e9c0mr363734ejr.45.1648047369103; Wed, 23 Mar 2022 07:56:09 -0700 (PDT) Received: from prevas-ravi.tritech.se ([80.208.64.233]) by smtp.gmail.com with ESMTPSA id p14-20020a05640210ce00b00413211746d4sm77256edu.51.2022.03.23.07.56.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 23 Mar 2022 07:56:08 -0700 (PDT) From: Rasmus Villemoes To: Tejun Heo , Lai Jiangshan Cc: =?utf-8?q?Andr=C3=A9_Pribil?= , Steven Walter , Oleksij Rempel , Esben Haabendal , Jiri Slaby , Pengutronix Kernel Team , Peter Hurley , linux-rt-users@vger.kernel.org, Rasmus Villemoes , linux-kernel@vger.kernel.org Subject: [RFC PATCH 2/2] workqueue: update sysfs handlers, allow setting RT policies Date: Wed, 23 Mar 2022 15:56:00 +0100 Message-Id: <20220323145600.2156689-3-linux@rasmusvillemoes.dk> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20220323145600.2156689-1-linux@rasmusvillemoes.dk> References: <20220323145600.2156689-1-linux@rasmusvillemoes.dk> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-rt-users@vger.kernel.org For this POC, this (ab)uses the "nice" attribute. It's of course not exactly pretty, but it avoids the problem of "what to show in the xyz file when using SCHED_NORMAL, and what to show in the nice file when using SCHED_RR/SCHED_FIFO". It's backwards-compatible, in that a bare integer is interpreted as a nice value, while an integer prefixed by "fifo:" or "rr:" chooses that RT scheduling policy with the associated value as the priority. The show method of course reflects what the store method accepts. Signed-off-by: Rasmus Villemoes --- kernel/workqueue.c | 54 ++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 47 insertions(+), 7 deletions(-) diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 9eb2ff7bcc04..a97f1aff809e 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -5538,13 +5538,34 @@ static ssize_t wq_nice_show(struct device *dev, struct device_attribute *attr, char *buf) { struct workqueue_struct *wq = dev_to_wq(dev); - int written; + struct workqueue_attrs *wqattrs; + const char *pfx; + int val; mutex_lock(&wq->mutex); - written = scnprintf(buf, PAGE_SIZE, "%d\n", wq->unbound_attrs->nice); + wqattrs = wq->unbound_attrs; + switch (wqattrs->policy) { + case SCHED_NORMAL: + pfx = ""; + val = wqattrs->nice; + break; + case SCHED_FIFO: + pfx = "fifo:"; + val = wqattrs->priority; + break; + case SCHED_RR: + pfx = "rr:"; + val = wqattrs->priority; + break; + default: + /* Shouldn't happen. */ + pfx = NULL; + } mutex_unlock(&wq->mutex); - return written; + if (!pfx) + return -EIO; + return scnprintf(buf, PAGE_SIZE, "%s%d\n", pfx, val); } /* prepare workqueue_attrs for sysfs store operations */ @@ -5568,6 +5589,24 @@ static ssize_t wq_nice_store(struct device *dev, struct device_attribute *attr, struct workqueue_struct *wq = dev_to_wq(dev); struct workqueue_attrs *attrs; int ret = -ENOMEM; + int policy, val; + + if (sscanf(buf, "fifo:%d", &val) == 1) + policy = SCHED_FIFO; + else if (sscanf(buf, "rr:%d", &val) == 1) + policy = SCHED_RR; + else if (sscanf(buf, "%d", &val) == 1) + policy = SCHED_NORMAL; + else + return -EINVAL; + + if (policy == SCHED_NORMAL) { + if (val < MIN_NICE || val > MAX_NICE) + return -EINVAL; + } else { + if (val <= 0 || val >= MAX_RT_PRIO) + return -EINVAL; + } apply_wqattrs_lock(); @@ -5575,11 +5614,12 @@ static ssize_t wq_nice_store(struct device *dev, struct device_attribute *attr, if (!attrs) goto out_unlock; - if (sscanf(buf, "%d", &attrs->nice) == 1 && - attrs->nice >= MIN_NICE && attrs->nice <= MAX_NICE) - ret = apply_workqueue_attrs_locked(wq, attrs); + attrs->policy = policy; + if (policy == SCHED_NORMAL) + attrs->nice = val; else - ret = -EINVAL; + attrs->priority = val; + ret = apply_workqueue_attrs_locked(wq, attrs); out_unlock: apply_wqattrs_unlock();