staging: lustre: move libcfs to lnet layer

The lustre file system has a layered architecture with
libcfs as the lowest layer and LNet layered on top. Then
on top of LNet we run the lustre client. This patch moves
the libcfs module code out of lustre into the lnet tree.
This fits into the long term goal of eventually merging
libcfs into LNet.

Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 1040 insertions, 0 deletions

diff --git a/drivers/staging/lustre/lnet/libcfs/linux/linux-cpu.c b/drivers/staging/lustre/lnet/libcfs/linux/linux-cpu.c
new file mode 100644
index 0000000..389fb9e
--- /dev/null
+++ b/drivers/staging/lustre/lnet/libcfs/linux/linux-cpu.c
@@ -0,0 +1,1040 @@
+/*
+ * GPL HEADER START
+ *
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 only,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License version 2 for more details (a copy is included
+ * in the LICENSE file that accompanied this code).
+ *
+ * GPL HEADER END
+ */
+/*
+ * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
+ *
+ * Copyright (c) 2012, 2015 Intel Corporation.
+ */
+/*
+ * This file is part of Lustre, http://www.lustre.org/
+ * Lustre is a trademark of Sun Microsystems, Inc.
+ *
+ * Author: liang@whamcloud.com
+ */
+
+#define DEBUG_SUBSYSTEM S_LNET
+
+#include <linux/cpu.h>
+#include <linux/sched.h>
+#include "../../../include/linux/libcfs/libcfs.h"
+
+#ifdef CONFIG_SMP
+
+/**
+ * modparam for setting number of partitions
+ *
+ *  0 : estimate best value based on cores or NUMA nodes
+ *  1 : disable multiple partitions
+ * >1 : specify number of partitions
+ */
+static int	cpu_npartitions;
+module_param(cpu_npartitions, int, 0444);
+MODULE_PARM_DESC(cpu_npartitions, "# of CPU partitions");
+
+/**
+ * modparam for setting CPU partitions patterns:
+ *
+ * i.e: "0[0,1,2,3] 1[4,5,6,7]", number before bracket is CPU partition ID,
+ *      number in bracket is processor ID (core or HT)
+ *
+ * i.e: "N 0[0,1] 1[2,3]" the first character 'N' means numbers in bracket
+ *       are NUMA node ID, number before bracket is CPU partition ID.
+ *
+ * NB: If user specified cpu_pattern, cpu_npartitions will be ignored
+ */
+static char	*cpu_pattern = "";
+module_param(cpu_pattern, charp, 0444);
+MODULE_PARM_DESC(cpu_pattern, "CPU partitions pattern");
+
+struct cfs_cpt_data {
+	/* serialize hotplug etc */
+	spinlock_t		cpt_lock;
+	/* reserved for hotplug */
+	unsigned long		cpt_version;
+	/* mutex to protect cpt_cpumask */
+	struct mutex		cpt_mutex;
+	/* scratch buffer for set/unset_node */
+	cpumask_t		*cpt_cpumask;
+};
+
+static struct cfs_cpt_data	cpt_data;
+
+void
+cfs_cpt_table_free(struct cfs_cpt_table *cptab)
+{
+	int	i;
+
+	if (cptab->ctb_cpu2cpt) {
+		LIBCFS_FREE(cptab->ctb_cpu2cpt,
+			    num_possible_cpus() *
+			    sizeof(cptab->ctb_cpu2cpt[0]));
+	}
+
+	for (i = 0; cptab->ctb_parts && i < cptab->ctb_nparts; i++) {
+		struct cfs_cpu_partition *part = &cptab->ctb_parts[i];
+
+		if (part->cpt_nodemask) {
+			LIBCFS_FREE(part->cpt_nodemask,
+				    sizeof(*part->cpt_nodemask));
+		}
+
+		if (part->cpt_cpumask)
+			LIBCFS_FREE(part->cpt_cpumask, cpumask_size());
+	}
+
+	if (cptab->ctb_parts) {
+		LIBCFS_FREE(cptab->ctb_parts,
+			    cptab->ctb_nparts * sizeof(cptab->ctb_parts[0]));
+	}
+
+	if (cptab->ctb_nodemask)
+		LIBCFS_FREE(cptab->ctb_nodemask, sizeof(*cptab->ctb_nodemask));
+	if (cptab->ctb_cpumask)
+		LIBCFS_FREE(cptab->ctb_cpumask, cpumask_size());
+
+	LIBCFS_FREE(cptab, sizeof(*cptab));
+}
+EXPORT_SYMBOL(cfs_cpt_table_free);
+
+struct cfs_cpt_table *
+cfs_cpt_table_alloc(unsigned int ncpt)
+{
+	struct cfs_cpt_table *cptab;
+	int	i;
+
+	LIBCFS_ALLOC(cptab, sizeof(*cptab));
+	if (!cptab)
+		return NULL;
+
+	cptab->ctb_nparts = ncpt;
+
+	LIBCFS_ALLOC(cptab->ctb_cpumask, cpumask_size());
+	LIBCFS_ALLOC(cptab->ctb_nodemask, sizeof(*cptab->ctb_nodemask));
+
+	if (!cptab->ctb_cpumask || !cptab->ctb_nodemask)
+		goto failed;
+
+	LIBCFS_ALLOC(cptab->ctb_cpu2cpt,
+		     num_possible_cpus() * sizeof(cptab->ctb_cpu2cpt[0]));
+	if (!cptab->ctb_cpu2cpt)
+		goto failed;
+
+	memset(cptab->ctb_cpu2cpt, -1,
+	       num_possible_cpus() * sizeof(cptab->ctb_cpu2cpt[0]));
+
+	LIBCFS_ALLOC(cptab->ctb_parts, ncpt * sizeof(cptab->ctb_parts[0]));
+	if (!cptab->ctb_parts)
+		goto failed;
+
+	for (i = 0; i < ncpt; i++) {
+		struct cfs_cpu_partition *part = &cptab->ctb_parts[i];
+
+		LIBCFS_ALLOC(part->cpt_cpumask, cpumask_size());
+		LIBCFS_ALLOC(part->cpt_nodemask, sizeof(*part->cpt_nodemask));
+		if (!part->cpt_cpumask || !part->cpt_nodemask)
+			goto failed;
+	}
+
+	spin_lock(&cpt_data.cpt_lock);
+	/* Reserved for hotplug */
+	cptab->ctb_version = cpt_data.cpt_version;
+	spin_unlock(&cpt_data.cpt_lock);
+
+	return cptab;
+
+ failed:
+	cfs_cpt_table_free(cptab);
+	return NULL;
+}
+EXPORT_SYMBOL(cfs_cpt_table_alloc);
+
+int
+cfs_cpt_table_print(struct cfs_cpt_table *cptab, char *buf, int len)
+{
+	char	*tmp = buf;
+	int	rc = 0;
+	int	i;
+	int	j;
+
+	for (i = 0; i < cptab->ctb_nparts; i++) {
+		if (len > 0) {
+			rc = snprintf(tmp, len, "%d\t: ", i);
+			len -= rc;
+		}
+
+		if (len <= 0) {
+			rc = -EFBIG;
+			goto out;
+		}
+
+		tmp += rc;
+		for_each_cpu(j, cptab->ctb_parts[i].cpt_cpumask) {
+			rc = snprintf(tmp, len, "%d ", j);
+			len -= rc;
+			if (len <= 0) {
+				rc = -EFBIG;
+				goto out;
+			}
+			tmp += rc;
+		}
+
+		*tmp = '\n';
+		tmp++;
+		len--;
+	}
+
+ out:
+	if (rc < 0)
+		return rc;
+
+	return tmp - buf;
+}
+EXPORT_SYMBOL(cfs_cpt_table_print);
+
+int
+cfs_cpt_number(struct cfs_cpt_table *cptab)
+{
+	return cptab->ctb_nparts;
+}
+EXPORT_SYMBOL(cfs_cpt_number);
+
+int
+cfs_cpt_weight(struct cfs_cpt_table *cptab, int cpt)
+{
+	LASSERT(cpt == CFS_CPT_ANY || (cpt >= 0 && cpt < cptab->ctb_nparts));
+
+	return cpt == CFS_CPT_ANY ?
+	       cpumask_weight(cptab->ctb_cpumask) :
+	       cpumask_weight(cptab->ctb_parts[cpt].cpt_cpumask);
+}
+EXPORT_SYMBOL(cfs_cpt_weight);
+
+int
+cfs_cpt_online(struct cfs_cpt_table *cptab, int cpt)
+{
+	LASSERT(cpt == CFS_CPT_ANY || (cpt >= 0 && cpt < cptab->ctb_nparts));
+
+	return cpt == CFS_CPT_ANY ?
+	       cpumask_any_and(cptab->ctb_cpumask,
+			       cpu_online_mask) < nr_cpu_ids :
+	       cpumask_any_and(cptab->ctb_parts[cpt].cpt_cpumask,
+			       cpu_online_mask) < nr_cpu_ids;
+}
+EXPORT_SYMBOL(cfs_cpt_online);
+
+cpumask_t *
+cfs_cpt_cpumask(struct cfs_cpt_table *cptab, int cpt)
+{
+	LASSERT(cpt == CFS_CPT_ANY || (cpt >= 0 && cpt < cptab->ctb_nparts));
+
+	return cpt == CFS_CPT_ANY ?
+	       cptab->ctb_cpumask : cptab->ctb_parts[cpt].cpt_cpumask;
+}
+EXPORT_SYMBOL(cfs_cpt_cpumask);
+
+nodemask_t *
+cfs_cpt_nodemask(struct cfs_cpt_table *cptab, int cpt)
+{
+	LASSERT(cpt == CFS_CPT_ANY || (cpt >= 0 && cpt < cptab->ctb_nparts));
+
+	return cpt == CFS_CPT_ANY ?
+	       cptab->ctb_nodemask : cptab->ctb_parts[cpt].cpt_nodemask;
+}
+EXPORT_SYMBOL(cfs_cpt_nodemask);
+
+int
+cfs_cpt_set_cpu(struct cfs_cpt_table *cptab, int cpt, int cpu)
+{
+	int	node;
+
+	LASSERT(cpt >= 0 && cpt < cptab->ctb_nparts);
+
+	if (cpu < 0 || cpu >= nr_cpu_ids || !cpu_online(cpu)) {
+		CDEBUG(D_INFO, "CPU %d is invalid or it's offline\n", cpu);
+		return 0;
+	}
+
+	if (cptab->ctb_cpu2cpt[cpu] != -1) {
+		CDEBUG(D_INFO, "CPU %d is already in partition %d\n",
+		       cpu, cptab->ctb_cpu2cpt[cpu]);
+		return 0;
+	}
+
+	cptab->ctb_cpu2cpt[cpu] = cpt;
+
+	LASSERT(!cpumask_test_cpu(cpu, cptab->ctb_cpumask));
+	LASSERT(!cpumask_test_cpu(cpu, cptab->ctb_parts[cpt].cpt_cpumask));
+
+	cpumask_set_cpu(cpu, cptab->ctb_cpumask);
+	cpumask_set_cpu(cpu, cptab->ctb_parts[cpt].cpt_cpumask);
+
+	node = cpu_to_node(cpu);
+
+	/* first CPU of @node in this CPT table */
+	if (!node_isset(node, *cptab->ctb_nodemask))
+		node_set(node, *cptab->ctb_nodemask);
+
+	/* first CPU of @node in this partition */
+	if (!node_isset(node, *cptab->ctb_parts[cpt].cpt_nodemask))
+		node_set(node, *cptab->ctb_parts[cpt].cpt_nodemask);
+
+	return 1;
+}
+EXPORT_SYMBOL(cfs_cpt_set_cpu);
+
+void
+cfs_cpt_unset_cpu(struct cfs_cpt_table *cptab, int cpt, int cpu)
+{
+	int	node;
+	int	i;
+
+	LASSERT(cpt == CFS_CPT_ANY || (cpt >= 0 && cpt < cptab->ctb_nparts));
+
+	if (cpu < 0 || cpu >= nr_cpu_ids) {
+		CDEBUG(D_INFO, "Invalid CPU id %d\n", cpu);
+		return;
+	}
+
+	if (cpt == CFS_CPT_ANY) {
+		/* caller doesn't know the partition ID */
+		cpt = cptab->ctb_cpu2cpt[cpu];
+		if (cpt < 0) { /* not set in this CPT-table */
+			CDEBUG(D_INFO, "Try to unset cpu %d which is not in CPT-table %p\n",
+			       cpt, cptab);
+			return;
+		}
+
+	} else if (cpt != cptab->ctb_cpu2cpt[cpu]) {
+		CDEBUG(D_INFO,
+		       "CPU %d is not in cpu-partition %d\n", cpu, cpt);
+		return;
+	}
+
+	LASSERT(cpumask_test_cpu(cpu, cptab->ctb_parts[cpt].cpt_cpumask));
+	LASSERT(cpumask_test_cpu(cpu, cptab->ctb_cpumask));
+
+	cpumask_clear_cpu(cpu, cptab->ctb_parts[cpt].cpt_cpumask);
+	cpumask_clear_cpu(cpu, cptab->ctb_cpumask);
+	cptab->ctb_cpu2cpt[cpu] = -1;
+
+	node = cpu_to_node(cpu);
+
+	LASSERT(node_isset(node, *cptab->ctb_parts[cpt].cpt_nodemask));
+	LASSERT(node_isset(node, *cptab->ctb_nodemask));
+
+	for_each_cpu(i, cptab->ctb_parts[cpt].cpt_cpumask) {
+		/* this CPT has other CPU belonging to this node? */
+		if (cpu_to_node(i) == node)
+			break;
+	}
+
+	if (i >= nr_cpu_ids)
+		node_clear(node, *cptab->ctb_parts[cpt].cpt_nodemask);
+
+	for_each_cpu(i, cptab->ctb_cpumask) {
+		/* this CPT-table has other CPU belonging to this node? */
+		if (cpu_to_node(i) == node)
+			break;
+	}
+
+	if (i >= nr_cpu_ids)
+		node_clear(node, *cptab->ctb_nodemask);
+}
+EXPORT_SYMBOL(cfs_cpt_unset_cpu);
+
+int
+cfs_cpt_set_cpumask(struct cfs_cpt_table *cptab, int cpt, cpumask_t *mask)
+{
+	int	i;
+
+	if (cpumask_weight(mask) == 0 ||
+	    cpumask_any_and(mask, cpu_online_mask) >= nr_cpu_ids) {
+		CDEBUG(D_INFO, "No online CPU is found in the CPU mask for CPU partition %d\n",
+		       cpt);
+		return 0;
+	}
+
+	for_each_cpu(i, mask) {
+		if (!cfs_cpt_set_cpu(cptab, cpt, i))
+			return 0;
+	}
+
+	return 1;
+}
+EXPORT_SYMBOL(cfs_cpt_set_cpumask);
+
+void
+cfs_cpt_unset_cpumask(struct cfs_cpt_table *cptab, int cpt, cpumask_t *mask)
+{
+	int	i;
+
+	for_each_cpu(i, mask)
+		cfs_cpt_unset_cpu(cptab, cpt, i);
+}
+EXPORT_SYMBOL(cfs_cpt_unset_cpumask);
+
+int
+cfs_cpt_set_node(struct cfs_cpt_table *cptab, int cpt, int node)
+{
+	cpumask_t	*mask;
+	int		rc;
+
+	if (node < 0 || node >= MAX_NUMNODES) {
+		CDEBUG(D_INFO,
+		       "Invalid NUMA id %d for CPU partition %d\n", node, cpt);
+		return 0;
+	}
+
+	mutex_lock(&cpt_data.cpt_mutex);
+
+	mask = cpt_data.cpt_cpumask;
+	cpumask_copy(mask, cpumask_of_node(node));
+
+	rc = cfs_cpt_set_cpumask(cptab, cpt, mask);
+
+	mutex_unlock(&cpt_data.cpt_mutex);
+
+	return rc;
+}
+EXPORT_SYMBOL(cfs_cpt_set_node);
+
+void
+cfs_cpt_unset_node(struct cfs_cpt_table *cptab, int cpt, int node)
+{
+	cpumask_t *mask;
+
+	if (node < 0 || node >= MAX_NUMNODES) {
+		CDEBUG(D_INFO,
+		       "Invalid NUMA id %d for CPU partition %d\n", node, cpt);
+		return;
+	}
+
+	mutex_lock(&cpt_data.cpt_mutex);
+
+	mask = cpt_data.cpt_cpumask;
+	cpumask_copy(mask, cpumask_of_node(node));
+
+	cfs_cpt_unset_cpumask(cptab, cpt, mask);
+
+	mutex_unlock(&cpt_data.cpt_mutex);
+}
+EXPORT_SYMBOL(cfs_cpt_unset_node);
+
+int
+cfs_cpt_set_nodemask(struct cfs_cpt_table *cptab, int cpt, nodemask_t *mask)
+{
+	int	i;
+
+	for_each_node_mask(i, *mask) {
+		if (!cfs_cpt_set_node(cptab, cpt, i))
+			return 0;
+	}
+
+	return 1;
+}
+EXPORT_SYMBOL(cfs_cpt_set_nodemask);
+
+void
+cfs_cpt_unset_nodemask(struct cfs_cpt_table *cptab, int cpt, nodemask_t *mask)
+{
+	int	i;
+
+	for_each_node_mask(i, *mask)
+		cfs_cpt_unset_node(cptab, cpt, i);
+}
+EXPORT_SYMBOL(cfs_cpt_unset_nodemask);
+
+void
+cfs_cpt_clear(struct cfs_cpt_table *cptab, int cpt)
+{
+	int	last;
+	int	i;
+
+	if (cpt == CFS_CPT_ANY) {
+		last = cptab->ctb_nparts - 1;
+		cpt = 0;
+	} else {
+		last = cpt;
+	}
+
+	for (; cpt <= last; cpt++) {
+		for_each_cpu(i, cptab->ctb_parts[cpt].cpt_cpumask)
+			cfs_cpt_unset_cpu(cptab, cpt, i);
+	}
+}
+EXPORT_SYMBOL(cfs_cpt_clear);
+
+int
+cfs_cpt_spread_node(struct cfs_cpt_table *cptab, int cpt)
+{
+	nodemask_t	*mask;
+	int		weight;
+	int		rotor;
+	int		node;
+
+	/* convert CPU partition ID to HW node id */
+
+	if (cpt < 0 || cpt >= cptab->ctb_nparts) {
+		mask = cptab->ctb_nodemask;
+		rotor = cptab->ctb_spread_rotor++;
+	} else {
+		mask = cptab->ctb_parts[cpt].cpt_nodemask;
+		rotor = cptab->ctb_parts[cpt].cpt_spread_rotor++;
+	}
+
+	weight = nodes_weight(*mask);
+	LASSERT(weight > 0);
+
+	rotor %= weight;
+
+	for_each_node_mask(node, *mask) {
+		if (rotor-- == 0)
+			return node;
+	}
+
+	LBUG();
+	return 0;
+}
+EXPORT_SYMBOL(cfs_cpt_spread_node);
+
+int
+cfs_cpt_current(struct cfs_cpt_table *cptab, int remap)
+{
+	int	cpu = smp_processor_id();
+	int	cpt = cptab->ctb_cpu2cpt[cpu];
+
+	if (cpt < 0) {
+		if (!remap)
+			return cpt;
+
+		/* don't return negative value for safety of upper layer,
+		 * instead we shadow the unknown cpu to a valid partition ID
+		 */
+		cpt = cpu % cptab->ctb_nparts;
+	}
+
+	return cpt;
+}
+EXPORT_SYMBOL(cfs_cpt_current);
+
+int
+cfs_cpt_of_cpu(struct cfs_cpt_table *cptab, int cpu)
+{
+	LASSERT(cpu >= 0 && cpu < nr_cpu_ids);
+
+	return cptab->ctb_cpu2cpt[cpu];
+}
+EXPORT_SYMBOL(cfs_cpt_of_cpu);
+
+int
+cfs_cpt_bind(struct cfs_cpt_table *cptab, int cpt)
+{
+	cpumask_t	*cpumask;
+	nodemask_t	*nodemask;
+	int		rc;
+	int		i;
+
+	LASSERT(cpt == CFS_CPT_ANY || (cpt >= 0 && cpt < cptab->ctb_nparts));
+
+	if (cpt == CFS_CPT_ANY) {
+		cpumask = cptab->ctb_cpumask;
+		nodemask = cptab->ctb_nodemask;
+	} else {
+		cpumask = cptab->ctb_parts[cpt].cpt_cpumask;
+		nodemask = cptab->ctb_parts[cpt].cpt_nodemask;
+	}
+
+	if (cpumask_any_and(cpumask, cpu_online_mask) >= nr_cpu_ids) {
+		CERROR("No online CPU found in CPU partition %d, did someone do CPU hotplug on system? You might need to reload Lustre modules to keep system working well.\n",
+		       cpt);
+		return -EINVAL;
+	}
+
+	for_each_online_cpu(i) {
+		if (cpumask_test_cpu(i, cpumask))
+			continue;
+
+		rc = set_cpus_allowed_ptr(current, cpumask);
+		set_mems_allowed(*nodemask);
+		if (rc == 0)
+			schedule(); /* switch to allowed CPU */
+
+		return rc;
+	}
+
+	/* don't need to set affinity because all online CPUs are covered */
+	return 0;
+}
+EXPORT_SYMBOL(cfs_cpt_bind);
+
+/**
+ * Choose max to \a number CPUs from \a node and set them in \a cpt.
+ * We always prefer to choose CPU in the same core/socket.
+ */
+static int
+cfs_cpt_choose_ncpus(struct cfs_cpt_table *cptab, int cpt,
+		     cpumask_t *node, int number)
+{
+	cpumask_t	*socket = NULL;
+	cpumask_t	*core = NULL;
+	int		rc = 0;
+	int		cpu;
+
+	LASSERT(number > 0);
+
+	if (number >= cpumask_weight(node)) {
+		while (!cpumask_empty(node)) {
+			cpu = cpumask_first(node);
+
+			rc = cfs_cpt_set_cpu(cptab, cpt, cpu);
+			if (!rc)
+				return -EINVAL;
+			cpumask_clear_cpu(cpu, node);
+		}
+		return 0;
+	}
+
+	/* allocate scratch buffer */
+	LIBCFS_ALLOC(socket, cpumask_size());
+	LIBCFS_ALLOC(core, cpumask_size());
+	if (!socket || !core) {
+		rc = -ENOMEM;
+		goto out;
+	}
+
+	while (!cpumask_empty(node)) {
+		cpu = cpumask_first(node);
+
+		/* get cpumask for cores in the same socket */
+		cpumask_copy(socket, topology_core_cpumask(cpu));
+		cpumask_and(socket, socket, node);
+
+		LASSERT(!cpumask_empty(socket));
+
+		while (!cpumask_empty(socket)) {
+			int     i;
+
+			/* get cpumask for hts in the same core */
+			cpumask_copy(core, topology_sibling_cpumask(cpu));
+			cpumask_and(core, core, node);
+
+			LASSERT(!cpumask_empty(core));
+
+			for_each_cpu(i, core) {
+				cpumask_clear_cpu(i, socket);
+				cpumask_clear_cpu(i, node);
+
+				rc = cfs_cpt_set_cpu(cptab, cpt, i);
+				if (!rc) {
+					rc = -EINVAL;
+					goto out;
+				}
+
+				if (--number == 0)
+					goto out;
+			}
+			cpu = cpumask_first(socket);
+		}
+	}
+
+ out:
+	if (socket)
+		LIBCFS_FREE(socket, cpumask_size());
+	if (core)
+		LIBCFS_FREE(core, cpumask_size());
+	return rc;
+}
+
+#define CPT_WEIGHT_MIN  4u
+
+static unsigned int
+cfs_cpt_num_estimate(void)
+{
+	unsigned nnode = num_online_nodes();
+	unsigned ncpu  = num_online_cpus();
+	unsigned ncpt;
+
+	if (ncpu <= CPT_WEIGHT_MIN) {
+		ncpt = 1;
+		goto out;
+	}
+
+	/* generate reasonable number of CPU partitions based on total number
+	 * of CPUs, Preferred N should be power2 and match this condition:
+	 * 2 * (N - 1)^2 < NCPUS <= 2 * N^2
+	 */
+	for (ncpt = 2; ncpu > 2 * ncpt * ncpt; ncpt <<= 1)
+		;
+
+	if (ncpt <= nnode) { /* fat numa system */
+		while (nnode > ncpt)
+			nnode >>= 1;
+
+	} else { /* ncpt > nnode */
+		while ((nnode << 1) <= ncpt)
+			nnode <<= 1;
+	}
+
+	ncpt = nnode;
+
+ out:
+#if (BITS_PER_LONG == 32)
+	/* config many CPU partitions on 32-bit system could consume
+	 * too much memory
+	 */
+	ncpt = min(2U, ncpt);
+#endif
+	while (ncpu % ncpt != 0)
+		ncpt--; /* worst case is 1 */
+
+	return ncpt;
+}
+
+static struct cfs_cpt_table *
+cfs_cpt_table_create(int ncpt)
+{
+	struct cfs_cpt_table *cptab = NULL;
+	cpumask_t	*mask = NULL;
+	int		cpt = 0;
+	int		num;
+	int		rc;
+	int		i;
+
+	rc = cfs_cpt_num_estimate();
+	if (ncpt <= 0)
+		ncpt = rc;
+
+	if (ncpt > num_online_cpus() || ncpt > 4 * rc) {
+		CWARN("CPU partition number %d is larger than suggested value (%d), your system may have performance issue or run out of memory while under pressure\n",
+		      ncpt, rc);
+	}
+
+	if (num_online_cpus() % ncpt != 0) {
+		CERROR("CPU number %d is not multiple of cpu_npartition %d, please try different cpu_npartitions value or set pattern string by cpu_pattern=STRING\n",
+		       (int)num_online_cpus(), ncpt);
+		goto failed;
+	}
+
+	cptab = cfs_cpt_table_alloc(ncpt);
+	if (!cptab) {
+		CERROR("Failed to allocate CPU map(%d)\n", ncpt);
+		goto failed;
+	}
+
+	num = num_online_cpus() / ncpt;
+	if (num == 0) {
+		CERROR("CPU changed while setting CPU partition\n");
+		goto failed;
+	}
+
+	LIBCFS_ALLOC(mask, cpumask_size());
+	if (!mask) {
+		CERROR("Failed to allocate scratch cpumask\n");
+		goto failed;
+	}
+
+	for_each_online_node(i) {
+		cpumask_copy(mask, cpumask_of_node(i));
+
+		while (!cpumask_empty(mask)) {
+			struct cfs_cpu_partition *part;
+			int    n;
+
+			if (cpt >= ncpt)
+				goto failed;
+
+			part = &cptab->ctb_parts[cpt];
+
+			n = num - cpumask_weight(part->cpt_cpumask);
+			LASSERT(n > 0);
+
+			rc = cfs_cpt_choose_ncpus(cptab, cpt, mask, n);
+			if (rc < 0)
+				goto failed;
+
+			LASSERT(num >= cpumask_weight(part->cpt_cpumask));
+			if (num == cpumask_weight(part->cpt_cpumask))
+				cpt++;
+		}
+	}
+
+	if (cpt != ncpt ||
+	    num != cpumask_weight(cptab->ctb_parts[ncpt - 1].cpt_cpumask)) {
+		CERROR("Expect %d(%d) CPU partitions but got %d(%d), CPU hotplug/unplug while setting?\n",
+		       cptab->ctb_nparts, num, cpt,
+		       cpumask_weight(cptab->ctb_parts[ncpt - 1].cpt_cpumask));
+		goto failed;
+	}
+
+	LIBCFS_FREE(mask, cpumask_size());
+
+	return cptab;
+
+ failed:
+	CERROR("Failed to setup CPU-partition-table with %d CPU-partitions, online HW nodes: %d, HW cpus: %d.\n",
+	       ncpt, num_online_nodes(), num_online_cpus());
+
+	if (mask)
+		LIBCFS_FREE(mask, cpumask_size());
+
+	if (cptab)
+		cfs_cpt_table_free(cptab);
+
+	return NULL;
+}
+
+static struct cfs_cpt_table *
+cfs_cpt_table_create_pattern(char *pattern)
+{
+	struct cfs_cpt_table	*cptab;
+	char			*str	= pattern;
+	int			node	= 0;
+	int			high;
+	int			ncpt;
+	int			c;
+
+	for (ncpt = 0;; ncpt++) { /* quick scan bracket */
+		str = strchr(str, '[');
+		if (!str)
+			break;
+		str++;
+	}
+
+	str = cfs_trimwhite(pattern);
+	if (*str == 'n' || *str == 'N') {
+		pattern = str + 1;
+		node = 1;
+	}
+
+	if (ncpt == 0 ||
+	    (node && ncpt > num_online_nodes()) ||
+	    (!node && ncpt > num_online_cpus())) {
+		CERROR("Invalid pattern %s, or too many partitions %d\n",
+		       pattern, ncpt);
+		return NULL;
+	}
+
+	high = node ? MAX_NUMNODES - 1 : nr_cpu_ids - 1;
+
+	cptab = cfs_cpt_table_alloc(ncpt);
+	if (!cptab) {
+		CERROR("Failed to allocate cpu partition table\n");
+		return NULL;
+	}
+
+	for (str = cfs_trimwhite(pattern), c = 0;; c++) {
+		struct cfs_range_expr	*range;
+		struct cfs_expr_list	*el;
+		char			*bracket = strchr(str, '[');
+		int			cpt;
+		int			rc;
+		int			i;
+		int			n;
+
+		if (!bracket) {
+			if (*str != 0) {
+				CERROR("Invalid pattern %s\n", str);
+				goto failed;
+			}
+			if (c != ncpt) {
+				CERROR("expect %d partitions but found %d\n",
+				       ncpt, c);
+				goto failed;
+			}
+			break;
+		}
+
+		if (sscanf(str, "%d%n", &cpt, &n) < 1) {
+			CERROR("Invalid cpu pattern %s\n", str);
+			goto failed;
+		}
+
+		if (cpt < 0 || cpt >= ncpt) {
+			CERROR("Invalid partition id %d, total partitions %d\n",
+			       cpt, ncpt);
+			goto failed;
+		}
+
+		if (cfs_cpt_weight(cptab, cpt) != 0) {
+			CERROR("Partition %d has already been set.\n", cpt);
+			goto failed;
+		}
+
+		str = cfs_trimwhite(str + n);
+		if (str != bracket) {
+			CERROR("Invalid pattern %s\n", str);
+			goto failed;
+		}
+
+		bracket = strchr(str, ']');
+		if (!bracket) {
+			CERROR("missing right bracket for cpt %d, %s\n",
+			       cpt, str);
+			goto failed;
+		}
+
+		if (cfs_expr_list_parse(str, (bracket - str) + 1,
+					0, high, &el) != 0) {
+			CERROR("Can't parse number range: %s\n", str);
+			goto failed;
+		}
+
+		list_for_each_entry(range, &el->el_exprs, re_link) {
+			for (i = range->re_lo; i <= range->re_hi; i++) {
+				if ((i - range->re_lo) % range->re_stride != 0)
+					continue;
+
+				rc = node ? cfs_cpt_set_node(cptab, cpt, i) :
+					    cfs_cpt_set_cpu(cptab, cpt, i);
+				if (!rc) {
+					cfs_expr_list_free(el);
+					goto failed;
+				}
+			}
+		}
+
+		cfs_expr_list_free(el);
+
+		if (!cfs_cpt_online(cptab, cpt)) {
+			CERROR("No online CPU is found on partition %d\n", cpt);
+			goto failed;
+		}
+
+		str = cfs_trimwhite(bracket + 1);
+	}
+
+	return cptab;
+
+ failed:
+	cfs_cpt_table_free(cptab);
+	return NULL;
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+static int
+cfs_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu)
+{
+	unsigned int  cpu = (unsigned long)hcpu;
+	bool	     warn;
+
+	switch (action) {
+	case CPU_DEAD:
+	case CPU_DEAD_FROZEN:
+	case CPU_ONLINE:
+	case CPU_ONLINE_FROZEN:
+		spin_lock(&cpt_data.cpt_lock);
+		cpt_data.cpt_version++;
+		spin_unlock(&cpt_data.cpt_lock);
+		/* Fall through */
+	default:
+		if (action != CPU_DEAD && action != CPU_DEAD_FROZEN) {
+			CDEBUG(D_INFO, "CPU changed [cpu %u action %lx]\n",
+			       cpu, action);
+			break;
+		}
+
+		mutex_lock(&cpt_data.cpt_mutex);
+		/* if all HTs in a core are offline, it may break affinity */
+		cpumask_copy(cpt_data.cpt_cpumask,
+			     topology_sibling_cpumask(cpu));
+		warn = cpumask_any_and(cpt_data.cpt_cpumask,
+				       cpu_online_mask) >= nr_cpu_ids;
+		mutex_unlock(&cpt_data.cpt_mutex);
+		CDEBUG(warn ? D_WARNING : D_INFO,
+		       "Lustre: can't support CPU plug-out well now, performance and stability could be impacted [CPU %u action: %lx]\n",
+		       cpu, action);
+	}
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block cfs_cpu_notifier = {
+	.notifier_call	= cfs_cpu_notify,
+	.priority	= 0
+};
+
+#endif
+
+void
+cfs_cpu_fini(void)
+{
+	if (cfs_cpt_table)
+		cfs_cpt_table_free(cfs_cpt_table);
+
+#ifdef CONFIG_HOTPLUG_CPU
+	unregister_hotcpu_notifier(&cfs_cpu_notifier);
+#endif
+	if (cpt_data.cpt_cpumask)
+		LIBCFS_FREE(cpt_data.cpt_cpumask, cpumask_size());
+}
+
+int
+cfs_cpu_init(void)
+{
+	LASSERT(!cfs_cpt_table);
+
+	memset(&cpt_data, 0, sizeof(cpt_data));
+
+	LIBCFS_ALLOC(cpt_data.cpt_cpumask, cpumask_size());
+	if (!cpt_data.cpt_cpumask) {
+		CERROR("Failed to allocate scratch buffer\n");
+		return -1;
+	}
+
+	spin_lock_init(&cpt_data.cpt_lock);
+	mutex_init(&cpt_data.cpt_mutex);
+
+#ifdef CONFIG_HOTPLUG_CPU
+	register_hotcpu_notifier(&cfs_cpu_notifier);
+#endif
+
+	if (*cpu_pattern != 0) {
+		cfs_cpt_table = cfs_cpt_table_create_pattern(cpu_pattern);
+		if (!cfs_cpt_table) {
+			CERROR("Failed to create cptab from pattern %s\n",
+			       cpu_pattern);
+			goto failed;
+		}
+
+	} else {
+		cfs_cpt_table = cfs_cpt_table_create(cpu_npartitions);
+		if (!cfs_cpt_table) {
+			CERROR("Failed to create ptable with npartitions %d\n",
+			       cpu_npartitions);
+			goto failed;
+		}
+	}
+
+	spin_lock(&cpt_data.cpt_lock);
+	if (cfs_cpt_table->ctb_version != cpt_data.cpt_version) {
+		spin_unlock(&cpt_data.cpt_lock);
+		CERROR("CPU hotplug/unplug during setup\n");
+		goto failed;
+	}
+	spin_unlock(&cpt_data.cpt_lock);
+
+	LCONSOLE(0, "HW CPU cores: %d, npartitions: %d\n",
+		 num_online_cpus(), cfs_cpt_number(cfs_cpt_table));
+	return 0;
+
+ failed:
+	cfs_cpu_fini();
+	return -1;
+}
+
+#endif