Added all files

4 files changed, 1099 insertions, 0 deletions

diff --git a/scheduler/alu/Makefile.am b/scheduler/alu/Makefile.am
new file mode 100644
index 000000000..d471a3f92
--- /dev/null
+++ b/scheduler/alu/Makefile.am
@@ -0,0 +1,3 @@
+SUBDIRS = src
+
+CLEANFILES = 
diff --git a/scheduler/alu/src/Makefile.am b/scheduler/alu/src/Makefile.am
new file mode 100644
index 000000000..eb7d0db07
--- /dev/null
+++ b/scheduler/alu/src/Makefile.am
@@ -0,0 +1,14 @@
+sched_LTLIBRARIES = alu.la
+scheddir = $(libdir)/glusterfs/$(PACKAGE_VERSION)/scheduler
+
+alu_la_LDFLAGS = -module -avoidversion
+
+alu_la_SOURCES = alu.c
+alu_la_LIBADD = $(top_builddir)/libglusterfs/src/libglusterfs.la
+
+noinst_HEADERS = alu.h
+
+AM_CFLAGS = -fPIC -D_FILE_OFFSET_BITS=64 -D_GNU_SOURCE -Wall -D$(GF_HOST_OS)\
+	-I$(top_srcdir)/libglusterfs/src -shared -nostartfiles $(GF_CFLAGS)
+
+CLEANFILES = 
diff --git a/scheduler/alu/src/alu.c b/scheduler/alu/src/alu.c
new file mode 100644
index 000000000..754c5e353
--- /dev/null
+++ b/scheduler/alu/src/alu.c
@@ -0,0 +1,993 @@
+/*
+  Copyright (c) 2006, 2007, 2008 Z RESEARCH, Inc. <http://www.zresearch.com>
+  This file is part of GlusterFS.
+
+  GlusterFS is free software; you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published
+  by the Free Software Foundation; either version 3 of the License,
+  or (at your option) any later version.
+
+  GlusterFS 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 for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see
+  <http://www.gnu.org/licenses/>.
+*/
+
+
+
+/* ALU code needs a complete re-write. This is one of the most important 
+ * part of GlusterFS and so needs more and more reviews and testing 
+ */
+
+#ifndef _CONFIG_H
+#define _CONFIG_H
+#include "config.h"
+#endif
+
+#include <sys/time.h>
+#include <stdint.h>
+#include "stack.h"
+#include "alu.h"
+
+#define ALU_DISK_USAGE_ENTRY_THRESHOLD_DEFAULT         (1 * GF_UNIT_GB)
+#define ALU_DISK_USAGE_EXIT_THRESHOLD_DEFAULT          (512 * GF_UNIT_MB)
+
+#define ALU_WRITE_USAGE_ENTRY_THRESHOLD_DEFAULT        25
+#define ALU_WRITE_USAGE_EXIT_THRESHOLD_DEFAULT         5
+
+#define ALU_READ_USAGE_ENTRY_THRESHOLD_DEFAULT         25
+#define ALU_READ_USAGE_EXIT_THRESHOLD_DEFAULT          5
+
+#define ALU_OPEN_FILES_USAGE_ENTRY_THRESHOLD_DEFAULT   1000
+#define ALU_OPEN_FILES_USAGE_EXIT_THRESHOLD_DEFAULT    100
+
+#define ALU_LIMITS_TOTAL_DISK_SIZE_DEFAULT             100
+
+#define ALU_REFRESH_INTERVAL_DEFAULT                   5
+#define ALU_REFRESH_CREATE_COUNT_DEFAULT               5
+
+
+static int64_t 
+get_stats_disk_usage (struct xlator_stats *this)
+{
+	return this->disk_usage;
+}
+
+static int64_t 
+get_stats_write_usage (struct xlator_stats *this)
+{
+	return this->write_usage;
+}
+
+static int64_t 
+get_stats_read_usage (struct xlator_stats *this)
+{
+	return this->read_usage;
+}
+
+static int64_t 
+get_stats_disk_speed (struct xlator_stats *this)
+{
+	return this->disk_speed;
+}
+
+static int64_t 
+get_stats_file_usage (struct xlator_stats *this)
+{
+	/* Avoid warning "defined but not used" */
+	(void) &get_stats_file_usage;    
+
+	return this->nr_files;
+}
+
+static int64_t 
+get_stats_free_disk (struct xlator_stats *this)
+{
+	if (this->total_disk_size > 0)
+		return (this->free_disk * 100) / this->total_disk_size;
+	return 0;
+}
+
+static int64_t 
+get_max_diff_write_usage (struct xlator_stats *max, struct xlator_stats *min)
+{
+	return (max->write_usage - min->write_usage);
+}
+
+static int64_t 
+get_max_diff_read_usage (struct xlator_stats *max, struct xlator_stats *min)
+{
+	return (max->read_usage - min->read_usage);
+}
+
+static int64_t 
+get_max_diff_disk_usage (struct xlator_stats *max, struct xlator_stats *min)
+{
+	return (max->disk_usage - min->disk_usage);
+}
+
+static int64_t 
+get_max_diff_disk_speed (struct xlator_stats *max, struct xlator_stats *min)
+{
+	return (max->disk_speed - min->disk_speed);
+}
+
+static int64_t 
+get_max_diff_file_usage (struct xlator_stats *max, struct xlator_stats *min)
+{
+	return (max->nr_files - min->nr_files);
+}
+
+
+int 
+alu_parse_options (xlator_t *xl, struct alu_sched *alu_sched)
+{
+	data_t *order = dict_get (xl->options, "scheduler.alu.order");
+	if (!order) {
+		gf_log (xl->name, GF_LOG_ERROR,
+			"option 'scheduler.alu.order' not specified");
+		return -1;
+	}
+	struct alu_threshold *_threshold_fn;
+	struct alu_threshold *tmp_threshold;
+	data_t *entry_fn = NULL;
+	data_t *exit_fn = NULL;
+	char *tmp_str = NULL;
+	char *order_str = strtok_r (order->data, ":", &tmp_str);
+	/* Get the scheduling priority order, specified by the user. */
+	while (order_str) {
+		gf_log ("alu", GF_LOG_DEBUG,
+			"alu_init: order string: %s",
+			order_str);
+		if (strcmp (order_str, "disk-usage") == 0) {
+			/* Disk usage */
+			_threshold_fn = 
+				CALLOC (1, sizeof (struct alu_threshold));
+			ERR_ABORT (_threshold_fn);
+			_threshold_fn->diff_value = get_max_diff_disk_usage;
+			_threshold_fn->sched_value = get_stats_disk_usage;
+			entry_fn = 
+				dict_get (xl->options, 
+					  "scheduler.alu.disk-usage.entry-threshold");
+			if (entry_fn) {
+				if (gf_string2bytesize (entry_fn->data, 
+							&alu_sched->entry_limit.disk_usage) != 0) {
+					gf_log (xl->name, GF_LOG_ERROR, 
+						"invalid number format \"%s\" "
+						"of \"option scheduler.alu."
+						"disk-usage.entry-threshold\"",
+						entry_fn->data);
+					return -1;
+				}
+			} else {
+				alu_sched->entry_limit.disk_usage = ALU_DISK_USAGE_ENTRY_THRESHOLD_DEFAULT;
+			}
+			_threshold_fn->entry_value = get_stats_disk_usage;
+			exit_fn = dict_get (xl->options, 
+					    "scheduler.alu.disk-usage.exit-threshold");
+			if (exit_fn) {
+				if (gf_string2bytesize (exit_fn->data, &alu_sched->exit_limit.disk_usage) != 0)	{
+					gf_log (xl->name, GF_LOG_ERROR, 
+						"invalid number format \"%s\" "
+						"of \"option scheduler.alu."
+						"disk-usage.exit-threshold\"", 
+						exit_fn->data);
+					return -1;
+				}
+			} else {
+				alu_sched->exit_limit.disk_usage = ALU_DISK_USAGE_EXIT_THRESHOLD_DEFAULT;
+			}
+			_threshold_fn->exit_value = get_stats_disk_usage;
+			tmp_threshold = alu_sched->threshold_fn;
+			if (!tmp_threshold) {
+				alu_sched->threshold_fn = _threshold_fn;
+			} else {
+				while (tmp_threshold->next) {
+					tmp_threshold = tmp_threshold->next;
+				}
+				tmp_threshold->next = _threshold_fn;
+			}
+			gf_log ("alu",
+				GF_LOG_DEBUG, "alu_init: = %"PRId64",%"PRId64"", 
+				alu_sched->entry_limit.disk_usage, 
+				alu_sched->exit_limit.disk_usage);
+			
+		} else if (strcmp (order_str, "write-usage") == 0) {
+			/* Handle "write-usage" */
+			
+			_threshold_fn = CALLOC (1, sizeof (struct alu_threshold));
+			ERR_ABORT (_threshold_fn);
+			_threshold_fn->diff_value = get_max_diff_write_usage;
+			_threshold_fn->sched_value = get_stats_write_usage;
+			entry_fn = dict_get (xl->options, 
+					     "scheduler.alu.write-usage.entry-threshold");
+			if (entry_fn) {
+				if (gf_string2bytesize (entry_fn->data, 
+							&alu_sched->entry_limit.write_usage) != 0) {
+					gf_log (xl->name, GF_LOG_ERROR, 
+						"invalid number format \"%s\" "
+						"of option scheduler.alu."
+						"write-usage.entry-threshold", 
+						entry_fn->data);
+					return -1;
+				}
+			} else {
+				alu_sched->entry_limit.write_usage = ALU_WRITE_USAGE_ENTRY_THRESHOLD_DEFAULT;
+			}
+			_threshold_fn->entry_value = get_stats_write_usage;
+			exit_fn = dict_get (xl->options, 
+					    "scheduler.alu.write-usage.exit-threshold");
+			if (exit_fn) {
+				if (gf_string2bytesize (exit_fn->data, 
+							&alu_sched->exit_limit.write_usage) != 0) {
+					gf_log (xl->name, GF_LOG_ERROR, 
+						"invalid number format \"%s\""
+						" of \"option scheduler.alu."
+						"write-usage.exit-threshold\"",
+						exit_fn->data);
+					return -1;
+				}
+			} else {
+				alu_sched->exit_limit.write_usage = ALU_WRITE_USAGE_EXIT_THRESHOLD_DEFAULT;
+			}
+			_threshold_fn->exit_value = get_stats_write_usage;
+			tmp_threshold = alu_sched->threshold_fn;
+			if (!tmp_threshold) {
+				alu_sched->threshold_fn = _threshold_fn;
+			} else {
+				while (tmp_threshold->next) {
+					tmp_threshold = tmp_threshold->next;
+				}
+				tmp_threshold->next = _threshold_fn;
+			}
+			gf_log (xl->name, GF_LOG_DEBUG, 
+				"alu_init: = %"PRId64",%"PRId64"", 
+				alu_sched->entry_limit.write_usage, 
+				alu_sched->exit_limit.write_usage);
+			
+		} else if (strcmp (order_str, "read-usage") == 0) {
+			/* Read usage */
+			
+			_threshold_fn = CALLOC (1, sizeof (struct alu_threshold));
+			ERR_ABORT (_threshold_fn);
+			_threshold_fn->diff_value = get_max_diff_read_usage;
+			_threshold_fn->sched_value = get_stats_read_usage;
+			entry_fn = dict_get (xl->options, 
+					     "scheduler.alu.read-usage.entry-threshold");
+			if (entry_fn) {
+				if (gf_string2bytesize (entry_fn->data, 
+							&alu_sched->entry_limit.read_usage) != 0) {
+					gf_log (xl->name, 
+						GF_LOG_ERROR, 
+						"invalid number format \"%s\" "
+						"of \"option scheduler.alu."
+						"read-usage.entry-threshold\"",
+						entry_fn->data);
+					return -1;
+				}
+			} else {
+				alu_sched->entry_limit.read_usage = ALU_READ_USAGE_ENTRY_THRESHOLD_DEFAULT;
+			}
+			_threshold_fn->entry_value = get_stats_read_usage;
+			exit_fn = dict_get (xl->options, 
+					    "scheduler.alu.read-usage.exit-threshold");
+			if (exit_fn)
+			{
+				if (gf_string2bytesize (exit_fn->data, 
+							&alu_sched->exit_limit.read_usage) != 0)
+				{
+					gf_log ("alu", GF_LOG_ERROR, 
+						"invalid number format \"%s\" "
+						"of \"option scheduler.alu."
+						"read-usage.exit-threshold\"", 
+						exit_fn->data);
+					return -1;
+				}
+			}
+			else
+			{
+				alu_sched->exit_limit.read_usage = ALU_READ_USAGE_EXIT_THRESHOLD_DEFAULT;
+			}
+			_threshold_fn->exit_value = get_stats_read_usage;
+			tmp_threshold = alu_sched->threshold_fn;
+			if (!tmp_threshold) {
+				alu_sched->threshold_fn = _threshold_fn;
+			}
+			else {
+				while (tmp_threshold->next) {
+					tmp_threshold = tmp_threshold->next;
+				}
+				tmp_threshold->next = _threshold_fn;
+			}
+			gf_log ("alu", GF_LOG_DEBUG, 
+				"alu_init: = %"PRId64",%"PRId64"", 
+				alu_sched->entry_limit.read_usage, 
+				alu_sched->exit_limit.read_usage);
+			
+		} else if (strcmp (order_str, "open-files-usage") == 0) {
+			/* Open files counter */
+			
+			_threshold_fn = CALLOC (1, sizeof (struct alu_threshold));
+			ERR_ABORT (_threshold_fn);
+			_threshold_fn->diff_value = get_max_diff_file_usage;
+			_threshold_fn->sched_value = get_stats_file_usage;
+			entry_fn = dict_get (xl->options, 
+					     "scheduler.alu.open-files-usage.entry-threshold");
+			if (entry_fn) {
+				if (gf_string2uint64 (entry_fn->data, 
+						      &alu_sched->entry_limit.nr_files) != 0)
+				{
+					gf_log ("alu", GF_LOG_ERROR, 
+						"invalid number format \"%s\" "
+						"of \"option scheduler.alu."
+						"open-files-usage.entry-"
+						"threshold\"", entry_fn->data);
+					return -1;
+				}
+			}
+			else
+			{
+				alu_sched->entry_limit.nr_files = ALU_OPEN_FILES_USAGE_ENTRY_THRESHOLD_DEFAULT;
+			}
+			_threshold_fn->entry_value = get_stats_file_usage;
+			exit_fn = dict_get (xl->options, 
+					    "scheduler.alu.open-files-usage.exit-threshold");
+			if (exit_fn)
+			{
+				if (gf_string2uint64 (exit_fn->data, 
+						      &alu_sched->exit_limit.nr_files) != 0)
+				{
+					gf_log ("alu", GF_LOG_ERROR, 
+						"invalid number format \"%s\" "
+						"of \"option scheduler.alu."
+						"open-files-usage.exit-"
+						"threshold\"", exit_fn->data);
+					return -1;
+				}
+			}
+			else
+			{
+				alu_sched->exit_limit.nr_files = ALU_OPEN_FILES_USAGE_EXIT_THRESHOLD_DEFAULT;
+			}
+			_threshold_fn->exit_value = get_stats_file_usage;
+			tmp_threshold = alu_sched->threshold_fn;
+			if (!tmp_threshold) {
+				alu_sched->threshold_fn = _threshold_fn;
+			}
+			else {
+				while (tmp_threshold->next) {
+					tmp_threshold = tmp_threshold->next;
+				}
+				tmp_threshold->next = _threshold_fn;
+			}
+			gf_log ("alu", GF_LOG_DEBUG, 
+				"alu.c->alu_init: = %"PRIu64",%"PRIu64"", 
+				alu_sched->entry_limit.nr_files, 
+				alu_sched->exit_limit.nr_files);
+			
+		} else if (strcmp (order_str, "disk-speed-usage") == 0) {
+			/* Disk speed */
+			
+			_threshold_fn = CALLOC (1, sizeof (struct alu_threshold));
+			ERR_ABORT (_threshold_fn);
+			_threshold_fn->diff_value = get_max_diff_disk_speed;
+			_threshold_fn->sched_value = get_stats_disk_speed;
+			entry_fn = dict_get (xl->options, 
+					     "scheduler.alu.disk-speed-usage.entry-threshold");
+			if (entry_fn) {
+				gf_log ("alu", GF_LOG_DEBUG,
+					"entry-threshold is given, "
+					"value is constant");
+			}
+			_threshold_fn->entry_value = NULL;
+			exit_fn = dict_get (xl->options, 
+					    "scheduler.alu.disk-speed-usage.exit-threshold");
+			if (exit_fn) {
+				gf_log ("alu", GF_LOG_DEBUG,
+					"exit-threshold is given, "
+					"value is constant");
+			}
+			_threshold_fn->exit_value = NULL;
+			tmp_threshold = alu_sched->threshold_fn;
+			if (!tmp_threshold) {
+				alu_sched->threshold_fn = _threshold_fn;
+			}
+			else {
+				while (tmp_threshold->next) {
+					tmp_threshold = tmp_threshold->next;
+				}
+				tmp_threshold->next = _threshold_fn;
+			}
+			
+		} else {
+			gf_log ("alu", GF_LOG_DEBUG,
+				"%s, unknown option provided to scheduler",
+				order_str);
+		}
+		order_str = strtok_r (NULL, ":", &tmp_str);
+	}
+	
+	return 0;
+}
+
+static int32_t
+alu_init (xlator_t *xl)
+{
+	struct alu_sched *alu_sched = NULL;
+	struct alu_limits *_limit_fn = NULL;
+	struct alu_limits *tmp_limits = NULL;
+	uint32_t min_free_disk = 0;
+	data_t *limits = NULL;
+  
+	alu_sched = CALLOC (1, sizeof (struct alu_sched));
+	ERR_ABORT (alu_sched);
+
+	{
+		alu_parse_options (xl, alu_sched);
+	}
+
+	/* Get the limits */
+	
+	limits = dict_get (xl->options, 
+			   "scheduler.limits.min-free-disk");
+	if (limits) {
+		_limit_fn = CALLOC (1, sizeof (struct alu_limits));
+		ERR_ABORT (_limit_fn);
+		_limit_fn->min_value = get_stats_free_disk;
+		_limit_fn->cur_value = get_stats_free_disk;
+		tmp_limits = alu_sched->limits_fn ;
+		_limit_fn->next = tmp_limits;
+		alu_sched->limits_fn = _limit_fn;
+		
+		if (gf_string2percent (limits->data, 
+				       &min_free_disk) != 0) {
+			gf_log ("alu", GF_LOG_ERROR, 
+				"invalid number format \"%s\" "
+				"of \"option scheduler.limits."
+				"min-free-disk\"", limits->data);
+			return -1;
+		}
+		alu_sched->spec_limit.free_disk = min_free_disk;
+		
+		if (alu_sched->spec_limit.free_disk >= 100) {
+			gf_log ("alu", GF_LOG_ERROR,
+				"check the \"option scheduler."
+				"limits.min-free-disk\", it should "
+				"be percentage value");
+			return -1;
+		}
+		alu_sched->spec_limit.total_disk_size = ALU_LIMITS_TOTAL_DISK_SIZE_DEFAULT; /* Its in % */
+		gf_log ("alu", GF_LOG_DEBUG,
+			"alu.limit.min-disk-free = %"PRId64"", 
+			_limit_fn->cur_value (&(alu_sched->spec_limit)));
+	}
+	
+	limits = dict_get (xl->options, 
+			   "scheduler.limits.max-open-files");
+	if (limits) {
+		// Update alu_sched->priority properly
+		_limit_fn = CALLOC (1, sizeof (struct alu_limits));
+		ERR_ABORT (_limit_fn);
+		_limit_fn->max_value = get_stats_file_usage;
+		_limit_fn->cur_value = get_stats_file_usage;
+		tmp_limits = alu_sched->limits_fn ;
+		_limit_fn->next = tmp_limits;
+		alu_sched->limits_fn = _limit_fn;
+		if (gf_string2uint64_base10 (limits->data, 
+					     &alu_sched->spec_limit.nr_files) != 0)
+		{
+			gf_log ("alu", GF_LOG_ERROR, 
+				"invalid number format '%s' of option "
+				"scheduler.limits.max-open-files", 
+				limits->data);
+			return -1;
+		}
+		
+		gf_log ("alu", GF_LOG_DEBUG,
+			"alu_init: limit.max-open-files = %"PRId64"",
+			_limit_fn->cur_value (&(alu_sched->spec_limit)));
+	}
+
+
+	/* Stats refresh options */
+	limits = dict_get (xl->options, 
+			   "scheduler.refresh-interval");
+	if (limits) {
+		if (gf_string2time (limits->data, 
+				    &alu_sched->refresh_interval) != 0)	{
+			gf_log ("alu", GF_LOG_ERROR, 
+				"invalid number format \"%s\" of "
+				"option scheduler.refresh-interval", 
+				limits->data);
+			return -1;
+		}
+	} else {
+		alu_sched->refresh_interval = ALU_REFRESH_INTERVAL_DEFAULT;
+	}
+	gettimeofday (&(alu_sched->last_stat_fetch), NULL);
+	
+	
+	limits = dict_get (xl->options, 
+			   "scheduler.alu.stat-refresh.num-file-create");
+	if (limits) {
+		if (gf_string2uint32 (limits->data, 
+				      &alu_sched->refresh_create_count) != 0)
+		{
+			gf_log ("alu", GF_LOG_ERROR, 
+				"invalid number format \"%s\" of \"option "
+				"alu.stat-refresh.num-file-create\"", 
+				limits->data);
+			return -1;
+		}
+	} else {
+		alu_sched->refresh_create_count = ALU_REFRESH_CREATE_COUNT_DEFAULT;
+	}
+
+	{
+		/* Build an array of child_nodes */
+		struct alu_sched_struct *sched_array = NULL;
+		xlator_list_t *trav_xl = xl->children;
+		data_t *data = NULL;
+		int32_t index = 0;
+		
+		while (trav_xl) {
+			index++;
+			trav_xl = trav_xl->next;
+		}
+		alu_sched->child_count = index;
+		sched_array = CALLOC (index, sizeof (struct alu_sched_struct));
+		ERR_ABORT (sched_array);
+		trav_xl = xl->children;
+		index = 0;
+		while (trav_xl) {
+			sched_array[index].xl = trav_xl->xlator;
+			sched_array[index].eligible = 1;
+			index++;
+			trav_xl = trav_xl->next;
+		}
+		alu_sched->array = sched_array;
+
+		data = dict_get (xl->options, 
+				 "scheduler.read-only-subvolumes");
+		if (data) {
+			char *child = NULL;
+			char *tmp = NULL;
+			char *childs_data = strdup (data->data);
+      
+			child = strtok_r (childs_data, ",", &tmp);
+			while (child) {
+				for (index = 1; index < alu_sched->child_count; index++) {
+					if (strcmp (alu_sched->array[index -1].xl->name, child) == 0) {
+						memcpy (&(alu_sched->array[index -1]), 
+							&(alu_sched->array[alu_sched->child_count -1]), 
+							sizeof (struct alu_sched_struct));
+						alu_sched->child_count--;
+						break;
+					}
+				}
+				child = strtok_r (NULL, ",", &tmp);
+			}
+		}
+	}
+
+	*((long *)xl->private) = (long)alu_sched;
+
+	/* Initialize all the alu_sched structure's elements */
+	{
+		alu_sched->sched_nodes_pending = 0;
+
+		alu_sched->min_limit.free_disk = 0x00FFFFFF;
+		alu_sched->min_limit.disk_usage = 0xFFFFFFFF;
+		alu_sched->min_limit.total_disk_size = 0xFFFFFFFF;
+		alu_sched->min_limit.disk_speed = 0xFFFFFFFF;
+		alu_sched->min_limit.write_usage = 0xFFFFFFFF;
+		alu_sched->min_limit.read_usage = 0xFFFFFFFF;
+		alu_sched->min_limit.nr_files = 0xFFFFFFFF;
+		alu_sched->min_limit.nr_clients = 0xFFFFFFFF;
+	}
+
+	pthread_mutex_init (&alu_sched->alu_mutex, NULL);
+	return 0;
+}
+
+static void
+alu_fini (xlator_t *xl)
+{
+	if (!xl)
+		return;
+	struct alu_sched *alu_sched = (struct alu_sched *)*((long *)xl->private);
+	struct alu_limits *limit = alu_sched->limits_fn;
+	struct alu_threshold *threshold = alu_sched->threshold_fn;
+	void *tmp = NULL;
+	pthread_mutex_destroy (&alu_sched->alu_mutex);
+	free (alu_sched->array);
+	while (limit) {
+		tmp = limit;
+		limit = limit->next;
+		free (tmp);
+	}
+	while (threshold) {
+		tmp = threshold;
+		threshold = threshold->next;
+		free (tmp);
+	}
+	free (alu_sched);
+}
+
+static int32_t 
+update_stat_array_cbk (call_frame_t *frame,
+		       void *cookie,
+		       xlator_t *xl,
+		       int32_t op_ret,
+		       int32_t op_errno,
+		       struct xlator_stats *trav_stats)
+{
+	struct alu_sched *alu_sched = (struct alu_sched *)*((long *)xl->private);
+	struct alu_limits *limits_fn = alu_sched->limits_fn;
+	int32_t idx = 0;
+  
+	pthread_mutex_lock (&alu_sched->alu_mutex);
+	for (idx = 0; idx < alu_sched->child_count; idx++) {
+		if (alu_sched->array[idx].xl == (xlator_t *)cookie)
+			break;
+	}
+	pthread_mutex_unlock (&alu_sched->alu_mutex);
+
+	if (op_ret == -1) {
+		alu_sched->array[idx].eligible = 0;
+	} else {
+		memcpy (&(alu_sched->array[idx].stats), trav_stats, sizeof (struct xlator_stats));
+    
+		/* Get stats from all the child node */
+		/* Here check the limits specified by the user to 
+		   consider the nodes to be used by scheduler */
+		alu_sched->array[idx].eligible = 1;
+		limits_fn = alu_sched->limits_fn;
+		while (limits_fn){
+			if (limits_fn->max_value && 
+			    (limits_fn->cur_value (trav_stats) > 
+			     limits_fn->max_value (&(alu_sched->spec_limit)))) {
+				alu_sched->array[idx].eligible = 0;
+			}
+			if (limits_fn->min_value && 
+			    (limits_fn->cur_value (trav_stats) < 
+			     limits_fn->min_value (&(alu_sched->spec_limit)))) {
+				alu_sched->array[idx].eligible = 0;
+			}
+			limits_fn = limits_fn->next;
+		}
+
+		/* Select minimum and maximum disk_usage */
+		if (trav_stats->disk_usage > alu_sched->max_limit.disk_usage) {
+			alu_sched->max_limit.disk_usage = trav_stats->disk_usage;
+		}
+		if (trav_stats->disk_usage < alu_sched->min_limit.disk_usage) {
+			alu_sched->min_limit.disk_usage = trav_stats->disk_usage;
+		}
+
+		/* Select minimum and maximum disk_speed */
+		if (trav_stats->disk_speed > alu_sched->max_limit.disk_speed) {
+			alu_sched->max_limit.disk_speed = trav_stats->disk_speed;
+		}
+		if (trav_stats->disk_speed < alu_sched->min_limit.disk_speed) {
+			alu_sched->min_limit.disk_speed = trav_stats->disk_speed;
+		}
+
+		/* Select minimum and maximum number of open files */
+		if (trav_stats->nr_files > alu_sched->max_limit.nr_files) {
+			alu_sched->max_limit.nr_files = trav_stats->nr_files;
+		}
+		if (trav_stats->nr_files < alu_sched->min_limit.nr_files) {
+			alu_sched->min_limit.nr_files = trav_stats->nr_files;
+		}
+
+		/* Select minimum and maximum write-usage */
+		if (trav_stats->write_usage > alu_sched->max_limit.write_usage) {
+			alu_sched->max_limit.write_usage = trav_stats->write_usage;
+		}
+		if (trav_stats->write_usage < alu_sched->min_limit.write_usage) {
+			alu_sched->min_limit.write_usage = trav_stats->write_usage;
+		}
+
+		/* Select minimum and maximum read-usage */
+		if (trav_stats->read_usage > alu_sched->max_limit.read_usage) {
+			alu_sched->max_limit.read_usage = trav_stats->read_usage;
+		}
+		if (trav_stats->read_usage < alu_sched->min_limit.read_usage) {
+			alu_sched->min_limit.read_usage = trav_stats->read_usage;
+		}
+
+		/* Select minimum and maximum free-disk */
+		if (trav_stats->free_disk > alu_sched->max_limit.free_disk) {
+			alu_sched->max_limit.free_disk = trav_stats->free_disk;
+		}
+		if (trav_stats->free_disk < alu_sched->min_limit.free_disk) {
+			alu_sched->min_limit.free_disk = trav_stats->free_disk;
+		}
+	}
+
+	STACK_DESTROY (frame->root);
+
+	return 0;
+}
+
+static void 
+update_stat_array (xlator_t *xl)
+{
+	/* This function schedules the file in one of the child nodes */
+	struct alu_sched *alu_sched = (struct alu_sched *)*((long *)xl->private);
+	int32_t idx = 0;
+	call_frame_t *frame = NULL;
+	call_pool_t *pool = xl->ctx->pool;
+
+	for (idx = 0 ; idx < alu_sched->child_count; idx++) {
+		frame = create_frame (xl, pool);
+
+		STACK_WIND_COOKIE (frame,
+				   update_stat_array_cbk, 
+				   alu_sched->array[idx].xl, //cookie
+				   alu_sched->array[idx].xl, 
+				   (alu_sched->array[idx].xl)->mops->stats,
+				   0); //flag
+	}
+	return;
+}
+
+static void 
+alu_update (xlator_t *xl)
+{
+	struct timeval tv;
+	struct alu_sched *alu_sched = (struct alu_sched *)*((long *)xl->private);
+
+	gettimeofday (&tv, NULL);
+	if (tv.tv_sec > (alu_sched->refresh_interval + alu_sched->last_stat_fetch.tv_sec)) {
+		/* Update the stats from all the server */
+		update_stat_array (xl);
+		alu_sched->last_stat_fetch.tv_sec = tv.tv_sec;
+	}
+}
+
+static xlator_t *
+alu_scheduler (xlator_t *xl, const void *path)
+{
+	/* This function schedules the file in one of the child nodes */
+	struct alu_sched *alu_sched = (struct alu_sched *)*((long *)xl->private);
+	int32_t sched_index = 0;
+	int32_t sched_index_orig = 0;
+	int32_t idx = 0;
+
+	alu_update (xl);
+
+	/* Now check each threshold one by one if some nodes are classified */
+	{
+		struct alu_threshold *trav_threshold = alu_sched->threshold_fn;
+		struct alu_threshold *tmp_threshold = alu_sched->sched_method;
+		struct alu_sched_node *tmp_sched_node;   
+
+		/* This pointer 'trav_threshold' contains function pointers according to spec file
+		   give by user, */
+		while (trav_threshold) {
+			/* This check is needed for seeing if already there are nodes in this criteria 
+			   to be scheduled */
+			if (!alu_sched->sched_nodes_pending) {
+				for (idx = 0; idx < alu_sched->child_count; idx++) {
+					if (!alu_sched->array[idx].eligible) {
+						continue;
+					}
+					if (trav_threshold->entry_value) {
+						if (trav_threshold->diff_value (&(alu_sched->max_limit),
+										&(alu_sched->array[idx].stats)) <
+						    trav_threshold->entry_value (&(alu_sched->entry_limit))) {
+							continue;
+						}
+					}
+					tmp_sched_node = CALLOC (1, sizeof (struct alu_sched_node));
+					ERR_ABORT (tmp_sched_node);
+					tmp_sched_node->index = idx;
+					if (!alu_sched->sched_node) {
+						alu_sched->sched_node = tmp_sched_node;
+					} else {
+						pthread_mutex_lock (&alu_sched->alu_mutex);
+						tmp_sched_node->next = alu_sched->sched_node;
+						alu_sched->sched_node = tmp_sched_node;
+						pthread_mutex_unlock (&alu_sched->alu_mutex);
+					}
+					alu_sched->sched_nodes_pending++;
+				}
+			} /* end of if (sched_nodes_pending) */
+
+			/* This loop is required to check the eligible nodes */
+			struct alu_sched_node *trav_sched_node;
+			while (alu_sched->sched_nodes_pending) {
+				trav_sched_node = alu_sched->sched_node;
+				sched_index = trav_sched_node->index;
+				if (alu_sched->array[sched_index].eligible)
+					break;
+				alu_sched->sched_node = trav_sched_node->next;
+				free (trav_sched_node);
+				alu_sched->sched_nodes_pending--;
+			}
+			if (alu_sched->sched_nodes_pending) {
+				/* There are some node in this criteria to be scheduled, no need 
+				 * to sort and check other methods 
+				 */
+				if (tmp_threshold && tmp_threshold->exit_value) {
+					/* verify the exit value && whether node is eligible or not */
+					if (tmp_threshold->diff_value (&(alu_sched->max_limit),
+								       &(alu_sched->array[sched_index].stats)) >
+					    tmp_threshold->exit_value (&(alu_sched->exit_limit))) {
+						/* Free the allocated info for the node :) */
+						pthread_mutex_lock (&alu_sched->alu_mutex);
+						alu_sched->sched_node = trav_sched_node->next;
+						free (trav_sched_node);
+						trav_sched_node = alu_sched->sched_node;
+						alu_sched->sched_nodes_pending--;
+						pthread_mutex_unlock (&alu_sched->alu_mutex);
+					}
+				} else {
+					/* if there is no exit value, then exit after scheduling once */
+					pthread_mutex_lock (&alu_sched->alu_mutex);
+					alu_sched->sched_node = trav_sched_node->next;
+					free (trav_sched_node);
+					trav_sched_node = alu_sched->sched_node;
+					alu_sched->sched_nodes_pending--;
+					pthread_mutex_unlock (&alu_sched->alu_mutex);
+				}
+	
+				alu_sched->sched_method = tmp_threshold; /* this is the method used for selecting */
+
+				/* */
+				if (trav_sched_node) {
+					tmp_sched_node = trav_sched_node;
+					while (trav_sched_node->next) {
+						trav_sched_node = trav_sched_node->next;
+					}
+					if (tmp_sched_node->next) {
+						pthread_mutex_lock (&alu_sched->alu_mutex);
+						alu_sched->sched_node = tmp_sched_node->next;
+						tmp_sched_node->next = NULL;
+						trav_sched_node->next = tmp_sched_node;
+						pthread_mutex_unlock (&alu_sched->alu_mutex);
+					}
+				}
+				/* return the scheduled node */
+				return alu_sched->array[sched_index].xl;
+			} /* end of if (pending_nodes) */
+      
+			tmp_threshold = trav_threshold;
+			trav_threshold = trav_threshold->next;
+		}
+	}
+  
+	/* This is used only when there is everything seems ok, or no eligible nodes */
+	sched_index_orig = alu_sched->sched_index;
+	alu_sched->sched_method = NULL;
+	while (1) {
+		//lock
+		pthread_mutex_lock (&alu_sched->alu_mutex);
+		sched_index = alu_sched->sched_index++;
+		alu_sched->sched_index = alu_sched->sched_index % alu_sched->child_count;
+		pthread_mutex_unlock (&alu_sched->alu_mutex);
+		//unlock
+		if (alu_sched->array[sched_index].eligible)
+			break;
+		if (sched_index_orig == (sched_index + 1) % alu_sched->child_count) {
+			gf_log ("alu", GF_LOG_WARNING, "No node is eligible to schedule");
+			//lock
+			pthread_mutex_lock (&alu_sched->alu_mutex);
+			alu_sched->sched_index++;
+			alu_sched->sched_index = alu_sched->sched_index % alu_sched->child_count;
+			pthread_mutex_unlock (&alu_sched->alu_mutex);
+			//unlock
+			break;
+		}
+	}
+	return alu_sched->array[sched_index].xl;
+}
+
+/**
+ * notify
+ */
+void
+alu_notify (xlator_t *xl, int32_t event, void *data)
+{
+	struct alu_sched *alu_sched = NULL; 
+	int32_t idx = 0;
+  
+	alu_sched = (struct alu_sched *)*((long *)xl->private);
+	if (!alu_sched)
+		return;
+
+	for (idx = 0; idx < alu_sched->child_count; idx++) {
+		if (alu_sched->array[idx].xl == (xlator_t *)data)
+			break;
+	}
+
+	switch (event)
+	{
+	case GF_EVENT_CHILD_UP:
+	{
+		//alu_sched->array[idx].eligible = 1;
+	}
+	break;
+	case GF_EVENT_CHILD_DOWN:
+	{
+		alu_sched->array[idx].eligible = 0;
+	}
+	break;
+	default:
+	{
+		;
+	}
+	break;
+	}
+
+}
+
+struct sched_ops sched = {
+	.init     = alu_init,
+	.fini     = alu_fini,
+	.update   = alu_update,
+	.schedule = alu_scheduler,
+	.notify   = alu_notify
+};
+
+struct volume_options options[] = {
+	{ .key   = { "scheduler.alu.order", "alu.order" },  
+	  .type  = GF_OPTION_TYPE_ANY 
+	},
+	{ .key   = { "scheduler.alu.disk-usage.entry-threshold", 
+		     "alu.disk-usage.entry-threshold" },  
+	  .type  = GF_OPTION_TYPE_SIZET
+	},
+	{ .key   = { "scheduler.alu.disk-usage.exit-threshold", 
+		     "alu.disk-usage.exit-threshold" },  
+	  .type  = GF_OPTION_TYPE_SIZET
+	},
+	{ .key   = { "scheduler.alu.write-usage.entry-threshold", 
+		     "alu.write-usage.entry-threshold" },  
+	  .type  = GF_OPTION_TYPE_SIZET
+	},
+	{ .key   = { "scheduler.alu.write-usage.exit-threshold", 
+		     "alu.write-usage.exit-threshold" },  
+	  .type  = GF_OPTION_TYPE_SIZET 
+	},
+	{ .key   = { "scheduler.alu.read-usage.entry-threshold", 
+		     "alu.read-usage.entry-threshold" },  
+	  .type  = GF_OPTION_TYPE_SIZET
+	},
+	{ .key   = { "scheduler.alu.read-usage.exit-threshold", 
+		     "alu.read-usage.exit-threshold" },  
+	  .type  = GF_OPTION_TYPE_SIZET 
+	},
+	{ .key   = { "scheduler.alu.open-files-usage.entry-threshold", 
+		     "alu.open-files-usage.entry-threshold" },  
+	  .type  = GF_OPTION_TYPE_INT
+	},
+	{ .key   = { "scheduler.alu.open-files-usage.exit-threshold", 
+		     "alu.open-files-usage.exit-threshold" },  
+	  .type  = GF_OPTION_TYPE_INT 
+	},
+	{ .key   = { "scheduler.read-only-subvolumes",
+		     "alu.read-only-subvolumes" },  
+	  .type  = GF_OPTION_TYPE_ANY 
+	},
+	{ .key   = { "scheduler.refresh-interval", 
+		     "alu.refresh-interval",
+		     "alu.stat-refresh.interval" },
+	  .type  = GF_OPTION_TYPE_TIME
+	},
+	{ .key   = { "scheduler.limits.min-free-disk", 
+		     "alu.limits.min-free-disk" },  
+	  .type  = GF_OPTION_TYPE_PERCENT
+	},
+	{ .key   = { "scheduler.alu.stat-refresh.num-file-create"
+		     "alu.stat-refresh.num-file-create"},  
+	  .type  = GF_OPTION_TYPE_INT
+	},
+	{ .key  =  {NULL}, }
+};
diff --git a/scheduler/alu/src/alu.h b/scheduler/alu/src/alu.h
new file mode 100644
index 000000000..a958bb4d2
--- /dev/null
+++ b/scheduler/alu/src/alu.h
@@ -0,0 +1,89 @@
+/*
+   Copyright (c) 2006, 2007, 2008 Z RESEARCH, Inc. <http://www.zresearch.com>
+   This file is part of GlusterFS.
+
+   GlusterFS is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published
+   by the Free Software Foundation; either version 3 of the License,
+   or (at your option) any later version.
+
+   GlusterFS 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 for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see
+   <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef _ALU_H
+#define _ALU_H
+
+#ifndef _CONFIG_H
+#define _CONFIG_H
+#include "config.h"
+#endif
+
+#include "scheduler.h"
+
+struct alu_sched;
+
+struct alu_sched_struct {
+  xlator_t *xl;
+  struct xlator_stats stats;
+  unsigned char eligible;
+};
+
+// Write better name for these functions
+struct alu_limits {
+  struct alu_limits *next;
+  int64_t (*max_value) (struct xlator_stats *); /* Max limit, specified by the user */
+  int64_t (*min_value) (struct xlator_stats *); /* Min limit, specified by the user */
+  int64_t (*cur_value) (struct xlator_stats *); /* Current values of variables got from stats call */
+};
+
+struct alu_threshold {
+  struct alu_threshold *next;
+  int64_t (*diff_value) (struct xlator_stats *max, struct xlator_stats *min); /* Diff b/w max and min */
+  int64_t (*entry_value) (struct xlator_stats *); /* Limit specified user */
+  int64_t (*exit_value) (struct xlator_stats *); /* Exit point for the limit */
+  int64_t (*sched_value) (struct xlator_stats *); /* This will return the index of the child area */
+};
+
+struct alu_sched_node {
+  struct alu_sched_node *next;
+  int32_t index;
+};
+
+struct alu_sched {
+  struct alu_limits *limits_fn;
+  struct alu_threshold *threshold_fn;
+  struct alu_sched_struct *array;
+  struct alu_sched_node *sched_node;
+  struct alu_threshold *sched_method;
+  struct xlator_stats max_limit;
+  struct xlator_stats min_limit;
+  struct xlator_stats entry_limit;
+  struct xlator_stats exit_limit;
+  struct xlator_stats spec_limit;     /* User given limit */
+
+  pthread_mutex_t alu_mutex;
+  struct timeval last_stat_fetch;
+  uint32_t refresh_interval;      /* in seconds */
+  uint32_t refresh_create_count;  /* num-file-create */
+
+  int32_t sched_nodes_pending;
+
+  int32_t sched_index;  /* used for round robin scheduling in case of many nodes getting the criteria match. */
+  int32_t child_count;
+
+};
+
+struct _alu_local_t {
+  int32_t call_count;
+};
+
+typedef struct _alu_local_t alu_local_t;
+
+#endif /* _ALU_H */