From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from m16.mail.163.com (m16.mail.163.com [220.197.31.5]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 1AD42158DDC; Fri, 28 Jun 2024 16:14:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=220.197.31.5 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719591251; cv=none; b=bYOfqV8GFJc/WuoTqd1FcO/IZ6XR6vXG4xi2hWpE/7NjGye5Tl7+uPS1Lqt2OnMqnJ2Uojvf3F7MPwHt+sKVFkZHewh1gG/pbQg474nJH/oGBhH4D5Y8FHdCdJSedq7nmmQZLAQB8O+XS5jyhWLh9BR91X6v/ozTnckMKvjvUi4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719591251; c=relaxed/simple; bh=/ZLjV4AtG6PE9RE64qHOYEVdhdNaKhQgUm25uI4izAI=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=q4snwVZLlMRNwz4vPt0Jy5hlYOu6vm4sjZ1UVXGZYQZr1SxjW/jOgvNCNUqXeajAG+WF52Bbvi3dqb5Pwvrwmo96VwdC47igZs3tV9zlp1q4f3PDZBltnA2+kOX3DwRZT79tknx1Yn9HlcjLchwLfaAMMfFYrY242dNJ0odHuG4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com; spf=pass smtp.mailfrom=163.com; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b=pSQNcblq; arc=none smtp.client-ip=220.197.31.5 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=163.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b="pSQNcblq" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=From:Subject:Date:Message-Id:MIME-Version; bh=e26+2 q+3hBU2DBzF5851MuqgEXt4Q/cdEKTEV/s7sag=; b=pSQNcblqjulPYUuVA1ewP bWx080z7JFM3P2O9bxeinUlDmYzbrJrm5dLbggXVXuQeQ1wDWcw9ycoWKjAg1S/h ChMqJ2UsMDooZJce0bHBm8jKxN9oFrlmXbOnsEoYelo5eVrJQgbaxHJcHdBKREbj 0J42/kHedGtk1ZAFIlCfR8= Received: from localhost (unknown [101.132.132.191]) by gzga-smtp-mta-g3-5 (Coremail) with SMTP id _____wDX_yoR4X5m0+qRAw--.37690S2; Sat, 29 Jun 2024 00:13:05 +0800 (CST) From: Xavier To: tj@kernel.org Cc: longman@redhat.com, mkoutny@suse.com, lizefan.x@bytedance.com, hannes@cmpxchg.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, Xavier Subject: [PATCH-cpuset v8 2/2] cpuset: use Union-Find to optimize the merging of cpumasks Date: Sat, 29 Jun 2024 00:13:02 +0800 Message-Id: <20240628161302.240043-3-xavier_qy@163.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240628161302.240043-1-xavier_qy@163.com> References: <20240628161302.240043-1-xavier_qy@163.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CM-TRANSID:_____wDX_yoR4X5m0+qRAw--.37690S2 X-Coremail-Antispam: 1Uf129KBjvJXoWxAFWfur4kKFyUZFWUJrW3Awb_yoWruF1fpF sakay2qrWrJryUGwsakay8Zw1ak3ykJayUtwnxGw1rtr17A3Z29a40qFs3KFWUZrWq9F1U uF9Igr47Wr18KFJanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x07Ubo7tUUUUU= X-CM-SenderInfo: 50dyxvpubt5qqrwthudrp/xtbBchAMEGWXv5R4dgABso The process of constructing scheduling domains involves multiple loops and repeated evaluations, leading to numerous redundant and ineffective assessments that impact code efficiency. Here, we use Union-Find to optimize the merging of cpumasks. By employing path compression and union by rank, we effectively reduce the number of lookups and merge comparisons. Signed-off-by: Xavier --- kernel/cgroup/cpuset.c | 96 ++++++++++++++++-------------------------- 1 file changed, 37 insertions(+), 59 deletions(-) diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index fe76045aa5..c435814ba8 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -45,6 +45,8 @@ #include #include #include +#include +#include DEFINE_STATIC_KEY_FALSE(cpusets_pre_enable_key); DEFINE_STATIC_KEY_FALSE(cpusets_enabled_key); @@ -172,9 +174,6 @@ struct cpuset { */ int attach_in_progress; - /* partition number for rebuild_sched_domains() */ - int pn; - /* for custom sched domain */ int relax_domain_level; @@ -208,6 +207,9 @@ struct cpuset { /* Remote partition silbling list anchored at remote_children */ struct list_head remote_sibling; + + /* Used to merge intersecting subsets for generate_sched_domains*/ + struct uf_node node; }; /* @@ -1007,7 +1009,7 @@ static int generate_sched_domains(cpumask_var_t **domains, struct cpuset *cp; /* top-down scan of cpusets */ struct cpuset **csa; /* array of all cpuset ptrs */ int csn; /* how many cpuset ptrs in csa so far */ - int i, j, k; /* indices for partition finding loops */ + int i, j; /* indices for partition finding loops */ cpumask_var_t *doms; /* resulting partition; i.e. sched domains */ struct sched_domain_attr *dattr; /* attributes for custom domains */ int ndoms = 0; /* number of sched domains in result */ @@ -1015,6 +1017,7 @@ static int generate_sched_domains(cpumask_var_t **domains, struct cgroup_subsys_state *pos_css; bool root_load_balance = is_sched_load_balance(&top_cpuset); bool cgrpv2 = cgroup_subsys_on_dfl(cpuset_cgrp_subsys); + int nslot_update; doms = NULL; dattr = NULL; @@ -1102,31 +1105,25 @@ static int generate_sched_domains(cpumask_var_t **domains, if (root_load_balance && (csn == 1)) goto single_root_domain; - for (i = 0; i < csn; i++) - csa[i]->pn = i; - ndoms = csn; - -restart: - /* Find the best partition (set of sched domains) */ - for (i = 0; i < csn; i++) { - struct cpuset *a = csa[i]; - int apn = a->pn; + if (!cgrpv2) { + for (i = 0; i < csn; i++) + uf_nodes_init(&csa[i]->node); - for (j = 0; j < csn; j++) { - struct cpuset *b = csa[j]; - int bpn = b->pn; - - if (apn != bpn && cpusets_overlap(a, b)) { - for (k = 0; k < csn; k++) { - struct cpuset *c = csa[k]; - - if (c->pn == bpn) - c->pn = apn; - } - ndoms--; /* one less element */ - goto restart; + /* Merge overlapping cpusets */ + for (i = 0; i < csn; i++) { + for (j = i + 1; j < csn; j++) { + if (cpusets_overlap(csa[i], csa[j])) + uf_union(&csa[i]->node, &csa[j]->node); } } + + /* Count the total number of domains */ + for (i = 0; i < csn; i++) { + if (csa[i]->node.parent == &csa[i]->node) + ndoms++; + } + } else { + ndoms = csn; } /* @@ -1159,44 +1156,25 @@ static int generate_sched_domains(cpumask_var_t **domains, } for (nslot = 0, i = 0; i < csn; i++) { - struct cpuset *a = csa[i]; - struct cpumask *dp; - int apn = a->pn; - - if (apn < 0) { - /* Skip completed partitions */ - continue; - } - - dp = doms[nslot]; - - if (nslot == ndoms) { - static int warnings = 10; - if (warnings) { - pr_warn("rebuild_sched_domains confused: nslot %d, ndoms %d, csn %d, i %d, apn %d\n", - nslot, ndoms, csn, i, apn); - warnings--; - } - continue; - } - - cpumask_clear(dp); - if (dattr) - *(dattr + nslot) = SD_ATTR_INIT; + nslot_update = 0; for (j = i; j < csn; j++) { - struct cpuset *b = csa[j]; - - if (apn == b->pn) { - cpumask_or(dp, dp, b->effective_cpus); + if (uf_find(&csa[j]->node) == &csa[i]->node) { + struct cpumask *dp = doms[nslot]; + + if (i == j) { + nslot_update = 1; + cpumask_clear(dp); + if (dattr) + *(dattr + nslot) = SD_ATTR_INIT; + } + cpumask_or(dp, dp, csa[j]->effective_cpus); cpumask_and(dp, dp, housekeeping_cpumask(HK_TYPE_DOMAIN)); if (dattr) - update_domain_attr_tree(dattr + nslot, b); - - /* Done with this partition */ - b->pn = -1; + update_domain_attr_tree(dattr + nslot, csa[j]); } } - nslot++; + if (nslot_update) + nslot++; } BUG_ON(nslot != ndoms); -- 2.45.2