From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from m15.mail.163.com (m15.mail.163.com [45.254.50.220]) by smtp.subspace.kernel.org (Postfix) with ESMTP id F282C2D05D; Thu, 20 Jun 2024 08:55:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.254.50.220 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718873711; cv=none; b=hHb3gnO8ky92uN3dIJLGYaytf0G/6wyC0EzIef88UoyUtbsYQ0c3uazFABvcQGP83k4yidlm7b1uDyV72WXXCfSsfplOa7Iv8suCcFkdwWs0wjk86BPz2sqVENRRj8e0KQTLn3qBZ7Wbby0m3LvknjKGwQTwAKnlLDYgNZcHYqU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718873711; c=relaxed/simple; bh=Zte5JUNqWfYMzsUShAtYW3hHHTnmNIinQoLo7kExpMU=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=GtG8cK/C837sqeZR9DdBToo5bUxPY0cjCoEksrJQHobg3k0/KSElqTibHDw6deFgkFBsCpwSqVhOu85WJIySs4KeHfdrf/6933qPlYTQKfWFV/Kb56xUpVktEOxr+46FpNuNJuWD0JlS2kffBXODINI/Vq/KHRUQ7nqh/MSCiiE= 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=BZf2uBSZ; arc=none smtp.client-ip=45.254.50.220 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="BZf2uBSZ" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=From:Subject:Date:Message-Id:MIME-Version; bh=f4H86 bcCOfTgkY5Xt2BTUJ/8giKcEdQStQuqAfO5dp8=; b=BZf2uBSZXrBHtEgFYvLkO nVgboCNiFOQHEnRh0IDaI9uvdRMjLNQRHr8wVn0h5+NMF24f7KjCdhpH9rrf/AnX 1tqNoUnjJhEphMmmFo5UUhejiLXjck4cBmhG65OLhIU0cXTLnqFs4nRoKi7uaUUE c0+AOWFqk9kJPXT6Hy66Rg= Received: from localhost (unknown [101.132.132.191]) by gzga-smtp-mta-g0-4 (Coremail) with SMTP id _____wDn5JjV7XNmrecAJA--.9351S2; Thu, 20 Jun 2024 16:52:38 +0800 (CST) From: Xavier To: longman@redhat.com, mkoutny@suse.com Cc: lizefan.x@bytedance.com, tj@kernel.org, hannes@cmpxchg.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Xavier Subject: [PATCH v4 v4 2/2] cpuset: use Union-Find to optimize the merging of cpumasks Date: Thu, 20 Jun 2024 16:52:33 +0800 Message-Id: <20240620085233.205690-3-xavier_qy@163.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240620085233.205690-1-xavier_qy@163.com> References: <20240603123101.590760-1-ghostxavier@sina.com> <20240620085233.205690-1-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:_____wDn5JjV7XNmrecAJA--.9351S2 X-Coremail-Antispam: 1Uf129KBjvJXoWxAFWfur4kKFyUZFWUJrW3Awb_yoWrurW5pF s3Cay2qrWrJryUGwsYk3y8Z34SkaykJa1Utw13Gw1fArnrA3Z29a40qFs5KayUuFyDCr1U uF9xKr47Wr1UKFDanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x07UadgZUUUUU= X-CM-SenderInfo: 50dyxvpubt5qqrwthudrp/1tbiZRYEEGXAmg963wABsz 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 | 95 +++++++++++++++--------------------------- 1 file changed, 34 insertions(+), 61 deletions(-) diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index fe76045aa5..7e527530f8 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -45,6 +45,7 @@ #include #include #include +#include DEFINE_STATIC_KEY_FALSE(cpusets_pre_enable_key); DEFINE_STATIC_KEY_FALSE(cpusets_enabled_key); @@ -172,9 +173,6 @@ struct cpuset { */ int attach_in_progress; - /* partition number for rebuild_sched_domains() */ - int pn; - /* for custom sched domain */ int relax_domain_level; @@ -1007,7 +1005,7 @@ 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 +1013,8 @@ 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); + struct uf_node *nodes; + int nslot_update; doms = NULL; dattr = NULL; @@ -1102,40 +1102,31 @@ 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; + nodes = uf_nodes_alloc(csn); + if (!nodes) + goto done; -restart: - /* Find the best partition (set of sched domains) */ + /* Merge overlapping cpusets */ for (i = 0; i < csn; i++) { - struct cpuset *a = csa[i]; - int apn = a->pn; - - 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; - } + for (j = i + 1; j < csn; j++) { + if (cpusets_overlap(csa[i], csa[j])) + uf_union(&nodes[i], &nodes[j]); } } + /* Count the total number of domains */ + for (i = 0; i < csn; i++) { + if ((nodes[i].parent == &nodes[i]) || !nodes[i].parent) + ndoms++; + } + /* * Now we know how many domains to create. * Convert to and populate cpu masks. */ doms = alloc_sched_domains(ndoms); if (!doms) - goto done; + goto free; /* * The rest of the code, including the scheduler, can deal with @@ -1159,47 +1150,29 @@ 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(&nodes[j]) == &nodes[i]) { + 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); - +free: + uf_nodes_free(nodes); done: kfree(csa); -- 2.45.2