From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-26.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8F57AC433B4 for ; Thu, 13 May 2021 17:54:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6E466611CE for ; Thu, 13 May 2021 17:54:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231453AbhEMRzQ (ORCPT ); Thu, 13 May 2021 13:55:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60982 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231468AbhEMRzL (ORCPT ); Thu, 13 May 2021 13:55:11 -0400 Received: from mail-pf1-x44a.google.com (mail-pf1-x44a.google.com [IPv6:2607:f8b0:4864:20::44a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4084FC061760 for ; Thu, 13 May 2021 10:54:00 -0700 (PDT) Received: by mail-pf1-x44a.google.com with SMTP id v6-20020a6261060000b029028e72db2cfdso18310755pfb.2 for ; Thu, 13 May 2021 10:54:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:message-id:mime-version:subject:from:to:cc; bh=4h31K2eiyFYJECD6jlXNAVHQd0JiCpNhIBmP2KCnD4c=; b=ofKtuEEcDD4yCmeEIuSCquHKovbV1slPISxwCQTyw4iykw/j2ncspJ0htUgP4AWxYm rSlAVzTDcK+inbYAWvLiarcwGutQB6dA5ySpZo+TT4zzJ0CuGmfcZfvem1/Rlhzt5xjs PD7X0d7fA30y+r8JmzzpGw6DXAFut/Bq2H184JYsu8js4vbXNOXQCqxa6W8R2B2I005W pdn6PN+RmkQNuZldg5kDR/QKAfGUpwHDkehDFK4Hw5ljWMF5uDt8Ou2FjZrHC0Q6nyzv ceIRFzEONJGOKB43ddrTtEQJf9Dg3oovy+TYa0zqrl5ob1hruZa2BSqWZJrSGeixShBq rqmQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc; bh=4h31K2eiyFYJECD6jlXNAVHQd0JiCpNhIBmP2KCnD4c=; b=uDihPD7inx0nYKAeCluJp4hKTSqcx5QP9inaarO+F5VzBv275qDDDfIAI0YPRe4MfD nhOwI6km/AdGANrgarxuYb+p4Jpv9e0IsOlweX4Zwz2W/KpFGvSouHrCYx7swbBB64Yf xFyYoCv/Ay3ok91zSayo24OnqHwjMvnCR+RGKTqFgIHlcjwjOTXaqTkqDa82RByrvhVT ajTvdtE5aPCl9s4jDKHBN41RWfmVjnlqn1i/ZBbPAfs2UbgRVYTh9ci2To3WxJ6a2I8b dnQNp4Wjq9PTpVYgtiyF6HVvc1O+ngSYe/PmhTHrOrtLGS/KjX+QHdVFH7y6t10EF5x9 Jdmw== X-Gm-Message-State: AOAM533z791HIVKs0w6V9Mq11qWlLeuevOQpfc3vEh3xyNPnW2nax6B2 PKzqNF53skPTMkzdL+1oJLcqeEt7jWg= X-Google-Smtp-Source: ABdhPJxHPu2QPsy8y6naNODAyq0c2q6tVGXFYvsc/7U+J2gWtm/+DmC2EGP8TzQrAjoke41LFE3sDd3/QLk= X-Received: from surenb1.mtv.corp.google.com ([2620:15c:211:200:f5d3:2ce1:2b19:735e]) (user=surenb job=sendgmr) by 2002:a17:90a:4487:: with SMTP id t7mr533181pjg.1.1620928439289; Thu, 13 May 2021 10:53:59 -0700 (PDT) Date: Thu, 13 May 2021 10:53:49 -0700 Message-Id: <20210513175349.959661-1-surenb@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.31.1.751.gd2f1c929bd-goog Subject: [PATCH 1/1] cgroup: make per-cgroup pressure stall tracking configurable From: Suren Baghdasaryan To: tj@kernel.org Cc: hannes@cmpxchg.org, lizefan.x@bytedance.com, mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, minchan@kernel.org, corbet@lwn.net, bristot@redhat.com, paulmck@kernel.org, rdunlap@infradead.org, akpm@linux-foundation.org, tglx@linutronix.de, macro@orcam.me.uk, viresh.kumar@linaro.org, mike.kravetz@oracle.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, surenb@google.com, kernel-team@android.com Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org PSI accounts stalls for each cgroup separately and aggregates it at each level of the hierarchy. This causes additional overhead with psi_avgs_work being called for each cgroup in the hierarchy. psi_avgs_work has been highly optimized, however on systems with large number of cgroups the overhead becomes noticeable. Systems which use PSI only at the system level could avoid this overhead if PSI can be configured to skip per-cgroup stall accounting. Add "cgroup_disable=pressure" kernel command-line option to allow requesting system-wide only pressure stall accounting. When set, it keeps system-wide accounting under /proc/pressure/ but skips accounting for individual cgroups and does not expose PSI nodes in cgroup hierarchy. Signed-off-by: Suren Baghdasaryan --- .../admin-guide/kernel-parameters.txt | 9 +++- include/linux/cgroup-defs.h | 1 + include/linux/cgroup.h | 7 +++ kernel/cgroup/cgroup.c | 46 +++++++++++++++++++ kernel/sched/psi.c | 8 +++- 5 files changed, 67 insertions(+), 4 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index cb89dbdedc46..653c62142f07 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -497,16 +497,21 @@ ccw_timeout_log [S390] See Documentation/s390/common_io.rst for details. - cgroup_disable= [KNL] Disable a particular controller - Format: {name of the controller(s) to disable} + cgroup_disable= [KNL] Disable a particular controller or optional feature + Format: {name of the controller(s) or feature(s) to disable} The effects of cgroup_disable=foo are: - foo isn't auto-mounted if you mount all cgroups in a single hierarchy - foo isn't visible as an individually mountable subsystem + - if foo is an optional feature then the feature is + disabled and corresponding cgroup files are not + created {Currently only "memory" controller deal with this and cut the overhead, others just disable the usage. So only cgroup_disable=memory is actually worthy} + Specifying "pressure" disables per-cgroup pressure + stall information accounting feature cgroup_no_v1= [KNL] Disable cgroup controllers and named hierarchies in v1 Format: { { controller | "all" | "named" } diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h index 559ee05f86b2..671f55cac0f0 100644 --- a/include/linux/cgroup-defs.h +++ b/include/linux/cgroup-defs.h @@ -110,6 +110,7 @@ enum { CFTYPE_NO_PREFIX = (1 << 3), /* (DON'T USE FOR NEW FILES) no subsys prefix */ CFTYPE_WORLD_WRITABLE = (1 << 4), /* (DON'T USE FOR NEW FILES) S_IWUGO */ CFTYPE_DEBUG = (1 << 5), /* create when cgroup_debug */ + CFTYPE_PRESSURE = (1 << 6), /* only if pressure feature is enabled */ /* internal flags, do not use outside cgroup core proper */ __CFTYPE_ONLY_ON_DFL = (1 << 16), /* only on default hierarchy */ diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 4f2f79de083e..b929f589968b 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -676,6 +676,8 @@ static inline struct psi_group *cgroup_psi(struct cgroup *cgrp) return &cgrp->psi; } +bool cgroup_psi_enabled(void); + static inline void cgroup_init_kthreadd(void) { /* @@ -735,6 +737,11 @@ static inline struct psi_group *cgroup_psi(struct cgroup *cgrp) return NULL; } +static inline bool cgroup_psi_enabled(void) +{ + return false; +} + static inline bool task_under_cgroup_hierarchy(struct task_struct *task, struct cgroup *ancestor) { diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index e049edd66776..c4b16c82e199 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -209,6 +209,22 @@ struct cgroup_namespace init_cgroup_ns = { static struct file_system_type cgroup2_fs_type; static struct cftype cgroup_base_files[]; +/* cgroup optional features */ +enum cgroup_opt_features { +#ifdef CONFIG_PSI + OPT_FEATURE_PRESSURE, +#endif + OPT_FEATURE_COUNT +}; + +static const char *cgroup_opt_feature_names[OPT_FEATURE_COUNT] = { +#ifdef CONFIG_PSI + "pressure", +#endif +}; + +static u16 cgroup_feature_disable_mask __read_mostly; + static int cgroup_apply_control(struct cgroup *cgrp); static void cgroup_finalize_control(struct cgroup *cgrp, int ret); static void css_task_iter_skip(struct css_task_iter *it, @@ -3631,6 +3647,18 @@ static void cgroup_pressure_release(struct kernfs_open_file *of) { psi_trigger_replace(&of->priv, NULL); } + +bool cgroup_psi_enabled(void) +{ + return (cgroup_feature_disable_mask & (1 << OPT_FEATURE_PRESSURE)) == 0; +} + +#else /* CONFIG_PSI */ +bool cgroup_psi_enabled(void) +{ + return false; +} + #endif /* CONFIG_PSI */ static int cgroup_freeze_show(struct seq_file *seq, void *v) @@ -3881,6 +3909,8 @@ static int cgroup_addrm_files(struct cgroup_subsys_state *css, restart: for (cft = cfts; cft != cft_end && cft->name[0] != '\0'; cft++) { /* does cft->flags tell us to skip this file on @cgrp? */ + if ((cft->flags & CFTYPE_PRESSURE) && !cgroup_psi_enabled()) + continue; if ((cft->flags & __CFTYPE_ONLY_ON_DFL) && !cgroup_on_dfl(cgrp)) continue; if ((cft->flags & __CFTYPE_NOT_ON_DFL) && cgroup_on_dfl(cgrp)) @@ -3958,6 +3988,9 @@ static int cgroup_init_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) WARN_ON(cft->ss || cft->kf_ops); + if ((cft->flags & CFTYPE_PRESSURE) && !cgroup_psi_enabled()) + continue; + if (cft->seq_start) kf_ops = &cgroup_kf_ops; else @@ -4866,6 +4899,7 @@ static struct cftype cgroup_base_files[] = { #ifdef CONFIG_PSI { .name = "io.pressure", + .flags = CFTYPE_PRESSURE, .seq_show = cgroup_io_pressure_show, .write = cgroup_io_pressure_write, .poll = cgroup_pressure_poll, @@ -4873,6 +4907,7 @@ static struct cftype cgroup_base_files[] = { }, { .name = "memory.pressure", + .flags = CFTYPE_PRESSURE, .seq_show = cgroup_memory_pressure_show, .write = cgroup_memory_pressure_write, .poll = cgroup_pressure_poll, @@ -4880,6 +4915,7 @@ static struct cftype cgroup_base_files[] = { }, { .name = "cpu.pressure", + .flags = CFTYPE_PRESSURE, .seq_show = cgroup_cpu_pressure_show, .write = cgroup_cpu_pressure_write, .poll = cgroup_pressure_poll, @@ -6216,6 +6252,13 @@ static int __init cgroup_disable(char *str) continue; cgroup_disable_mask |= 1 << i; } + + for (i = 0; i < OPT_FEATURE_COUNT; i++) { + if (strcmp(token, cgroup_opt_feature_names[i])) + continue; + cgroup_feature_disable_mask |= 1 << i; + break; + } } return 1; } @@ -6514,6 +6557,9 @@ static ssize_t show_delegatable_files(struct cftype *files, char *buf, if (!(cft->flags & CFTYPE_NS_DELEGATABLE)) continue; + if ((cft->flags & CFTYPE_PRESSURE) && !cgroup_psi_enabled()) + continue; + if (prefix) ret += snprintf(buf + ret, size - ret, "%s.", prefix); diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c index cc25a3cff41f..c73efd7d4fba 100644 --- a/kernel/sched/psi.c +++ b/kernel/sched/psi.c @@ -747,9 +747,12 @@ static struct psi_group *iterate_groups(struct task_struct *task, void **iter) #ifdef CONFIG_CGROUPS struct cgroup *cgroup = NULL; - if (!*iter) + if (!*iter) { + /* Skip to psi_system if per-cgroup accounting is disabled */ + if (!cgroup_psi_enabled()) + goto update_sys; cgroup = task->cgroups->dfl_cgrp; - else if (*iter == &psi_system) + } else if (*iter == &psi_system) return NULL; else cgroup = cgroup_parent(*iter); @@ -758,6 +761,7 @@ static struct psi_group *iterate_groups(struct task_struct *task, void **iter) *iter = cgroup; return cgroup_psi(cgroup); } +update_sys: #else if (*iter) return NULL; -- 2.31.1.607.g51e8a6a459-goog