+++ /dev/null
-From: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
-Subject: dm-mpath: add service-time oriented dynamic load balancer
-References: FATE#303862,FATE#302108
-
-This patch adds a service time oriented dynamic load balancer,
-dm-service-time.
-
-
-Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
-Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
-Signed-off-by: Hannes Reinecke <hare@suse.de>
-
-Index: linux-2.6.27/drivers/md/Makefile
-===================================================================
---- linux-2.6.27.orig/drivers/md/Makefile
-+++ linux-2.6.27/drivers/md/Makefile
-@@ -33,7 +33,8 @@ obj-$(CONFIG_BLK_DEV_DM) += dm-mod.o
- obj-$(CONFIG_DM_CRYPT) += dm-crypt.o
- obj-$(CONFIG_DM_DELAY) += dm-delay.o
- obj-$(CONFIG_DM_MULTIPATH) += dm-multipath.o dm-round-robin.o \
-- dm-least-pending.o dm-queue-length.o
-+ dm-least-pending.o dm-queue-length.o \
-+ dm-service-time.o
- obj-$(CONFIG_DM_SNAPSHOT) += dm-snapshot.o
- obj-$(CONFIG_DM_MIRROR) += dm-mirror.o dm-regions.o dm-log.o
- obj-$(CONFIG_DM_RAID45) += dm-raid45.o dm-log.o dm-memcache.o \
-Index: linux-2.6.27/drivers/md/dm-service-time.c
-===================================================================
---- /dev/null
-+++ linux-2.6.27/drivers/md/dm-service-time.c
-@@ -0,0 +1,312 @@
-+/*
-+ * Copyright (C) 2007-2008 NEC Corporation. All Rights Reserved.
-+ *
-+ * Module Author: Kiyoshi Ueda
-+ *
-+ * This file is released under the GPL.
-+ *
-+ * Throughput oriented path selector.
-+ */
-+
-+#include "dm.h"
-+#include "dm-path-selector.h"
-+
-+#define DM_MSG_PREFIX "multipath service-time"
-+#define ST_MIN_IO 2
-+#define ST_VERSION "0.1.0"
-+
-+struct selector {
-+ struct list_head valid_paths;
-+ struct list_head failed_paths;
-+};
-+
-+struct path_info {
-+ struct list_head list;
-+ struct dm_path *path;
-+ unsigned int repeat_count;
-+
-+ atomic_t in_flight; /* Total size of in-flight I/Os */
-+ size_t perf; /* Recent performance of the path */
-+ sector_t last_sectors; /* Total sectors of the last disk_stat_read */
-+ size_t last_io_ticks; /* io_ticks of the last disk_stat_read */
-+};
-+
-+static struct selector *alloc_selector(void)
-+{
-+ struct selector *s = kzalloc(sizeof(*s), GFP_KERNEL);
-+
-+ if (s) {
-+ INIT_LIST_HEAD(&s->valid_paths);
-+ INIT_LIST_HEAD(&s->failed_paths);
-+ }
-+
-+ return s;
-+}
-+
-+static int st_create(struct path_selector *ps, unsigned argc, char **argv)
-+{
-+ struct selector *s = alloc_selector();
-+
-+ if (!s)
-+ return -ENOMEM;
-+
-+ ps->context = s;
-+ return 0;
-+}
-+
-+static void free_paths(struct list_head *paths)
-+{
-+ struct path_info *pi, *next;
-+
-+ list_for_each_entry_safe(pi, next, paths, list) {
-+ list_del(&pi->list);
-+ pi->path->pscontext = NULL;
-+ kfree(pi);
-+ }
-+}
-+
-+static void st_destroy(struct path_selector *ps)
-+{
-+ struct selector *s = (struct selector *) ps->context;
-+
-+ free_paths(&s->valid_paths);
-+ free_paths(&s->failed_paths);
-+ kfree(s);
-+ ps->context = NULL;
-+}
-+
-+static int st_status(struct path_selector *ps, struct dm_path *path,
-+ status_type_t type, char *result, unsigned int maxlen)
-+{
-+ int sz = 0;
-+ struct path_info *pi;
-+
-+ if (!path)
-+ DMEMIT("0 ");
-+ else {
-+ pi = path->pscontext;
-+
-+ switch (type) {
-+ case STATUSTYPE_INFO:
-+ DMEMIT("if:%08lu pf:%06lu ",
-+ (unsigned long) atomic_read(&pi->in_flight),
-+ pi->perf);
-+ break;
-+ case STATUSTYPE_TABLE:
-+ DMEMIT("%u ", pi->repeat_count);
-+ break;
-+ }
-+ }
-+
-+ return sz;
-+}
-+
-+static int st_add_path(struct path_selector *ps, struct dm_path *path,
-+ int argc, char **argv, char **error)
-+{
-+ struct selector *s = (struct selector *) ps->context;
-+ struct path_info *pi;
-+ unsigned int repeat_count = ST_MIN_IO;
-+ struct gendisk *disk = path->dev->bdev->bd_disk;
-+
-+ if (argc > 1) {
-+ *error = "service-time ps: incorrect number of arguments";
-+ return -EINVAL;
-+ }
-+
-+ /* First path argument is number of I/Os before switching path. */
-+ if ((argc == 1) && (sscanf(argv[0], "%u", &repeat_count) != 1)) {
-+ *error = "service-time ps: invalid repeat count";
-+ return -EINVAL;
-+ }
-+
-+ /* allocate the path */
-+ pi = kmalloc(sizeof(*pi), GFP_KERNEL);
-+ if (!pi) {
-+ *error = "service-time ps: Error allocating path context";
-+ return -ENOMEM;
-+ }
-+
-+ pi->path = path;
-+ pi->repeat_count = repeat_count;
-+
-+ pi->perf = 0;
-+ pi->last_sectors = disk_stat_read(disk, sectors[READ])
-+ + disk_stat_read(disk, sectors[WRITE]);
-+ pi->last_io_ticks = disk_stat_read(disk, io_ticks);
-+ atomic_set(&pi->in_flight, 0);
-+
-+ path->pscontext = pi;
-+
-+ list_add_tail(&pi->list, &s->valid_paths);
-+
-+ return 0;
-+}
-+
-+static void st_fail_path(struct path_selector *ps, struct dm_path *path)
-+{
-+ struct selector *s = (struct selector *) ps->context;
-+ struct path_info *pi = path->pscontext;
-+
-+ list_move(&pi->list, &s->failed_paths);
-+}
-+
-+static int st_reinstate_path(struct path_selector *ps, struct dm_path *path)
-+{
-+ struct selector *s = (struct selector *) ps->context;
-+ struct path_info *pi = path->pscontext;
-+
-+ list_move_tail(&pi->list, &s->valid_paths);
-+
-+ return 0;
-+}
-+
-+static void stats_update(struct path_info *pi)
-+{
-+ sector_t sectors;
-+ size_t io_ticks, tmp;
-+ struct gendisk *disk = pi->path->dev->bdev->bd_disk;
-+
-+ sectors = disk_stat_read(disk, sectors[READ])
-+ + disk_stat_read(disk, sectors[WRITE]);
-+ io_ticks = disk_stat_read(disk, io_ticks);
-+
-+ if ((sectors != pi->last_sectors) && (io_ticks != pi->last_io_ticks)) {
-+ tmp = (sectors - pi->last_sectors) << 9;
-+ do_div(tmp, jiffies_to_msecs((io_ticks - pi->last_io_ticks)));
-+ pi->perf = tmp;
-+
-+ pi->last_sectors = sectors;
-+ pi->last_io_ticks = io_ticks;
-+ }
-+}
-+
-+static int st_compare_load(struct path_info *pi1, struct path_info *pi2,
-+ size_t new_io)
-+{
-+ size_t if1, if2;
-+
-+ if1 = atomic_read(&pi1->in_flight);
-+ if2 = atomic_read(&pi2->in_flight);
-+
-+ /*
-+ * Case 1: No performace data available. Choose less loaded path.
-+ */
-+ if (!pi1->perf || !pi2->perf)
-+ return if1 - if2;
-+
-+ /*
-+ * Case 2: Calculate service time. Choose faster path.
-+ * if ((if1+new_io)/pi1->perf < (if2+new_io)/pi2->perf) pi1.
-+ * if ((if1+new_io)/pi1->perf > (if2+new_io)/pi2->perf) pi2.
-+ * To avoid do_div(), use
-+ * if ((if1+new_io)*pi2->perf < (if2+new_io)*pi1->perf) pi1.
-+ * if ((if1+new_io)*pi2->perf > (if2+new_io)*pi1->perf) pi2.
-+ */
-+ if1 = (if1 + new_io) << 10;
-+ if2 = (if2 + new_io) << 10;
-+ do_div(if1, pi1->perf);
-+ do_div(if2, pi2->perf);
-+
-+ if (if1 != if2)
-+ return if1 - if2;
-+
-+ /*
-+ * Case 3: Service time is equal. Choose faster path.
-+ */
-+ return pi2->perf - pi1->perf;
-+}
-+
-+static struct dm_path *st_select_path(struct path_selector *ps,
-+ unsigned *repeat_count, size_t nr_bytes)
-+{
-+ struct selector *s = (struct selector *) ps->context;
-+ struct path_info *pi = NULL, *best = NULL;
-+
-+ if (list_empty(&s->valid_paths))
-+ return NULL;
-+
-+ /* Change preferred (first in list) path to evenly balance. */
-+ list_move_tail(s->valid_paths.next, &s->valid_paths);
-+
-+ /* Update performance information before best path selection */
-+ list_for_each_entry(pi, &s->valid_paths, list)
-+ stats_update(pi);
-+
-+ list_for_each_entry(pi, &s->valid_paths, list) {
-+ if (!best)
-+ best = pi;
-+ else if (st_compare_load(pi, best, nr_bytes) < 0)
-+ best = pi;
-+ }
-+
-+ if (best) {
-+ *repeat_count = best->repeat_count;
-+ return best->path;
-+ }
-+
-+ return NULL;
-+}
-+
-+static int st_start_io(struct path_selector *ps, struct dm_path *path,
-+ size_t nr_bytes)
-+{
-+ struct path_info *pi = path->pscontext;
-+
-+ atomic_add(nr_bytes, &pi->in_flight);
-+
-+ return 0;
-+}
-+
-+static int st_end_io(struct path_selector *ps, struct dm_path *path,
-+ size_t nr_bytes)
-+{
-+ struct path_info *pi = path->pscontext;
-+
-+ atomic_sub(nr_bytes, &pi->in_flight);
-+
-+ return 0;
-+}
-+
-+static struct path_selector_type st_ps = {
-+ .name = "service-time",
-+ .module = THIS_MODULE,
-+ .table_args = 1,
-+ .info_args = 2,
-+ .create = st_create,
-+ .destroy = st_destroy,
-+ .status = st_status,
-+ .add_path = st_add_path,
-+ .fail_path = st_fail_path,
-+ .reinstate_path = st_reinstate_path,
-+ .select_path = st_select_path,
-+ .start_io = st_start_io,
-+ .end_io = st_end_io,
-+};
-+
-+static int __init dm_st_init(void)
-+{
-+ int r = dm_register_path_selector(&st_ps);
-+
-+ if (r < 0)
-+ DMERR("register failed %d", r);
-+
-+ DMINFO("version " ST_VERSION " loaded");
-+
-+ return r;
-+}
-+
-+static void __exit dm_st_exit(void)
-+{
-+ int r = dm_unregister_path_selector(&st_ps);
-+
-+ if (r < 0)
-+ DMERR("unregister failed %d", r);
-+}
-+
-+module_init(dm_st_init);
-+module_exit(dm_st_exit);
-+
-+MODULE_DESCRIPTION(DM_NAME " throughput oriented path selector");
-+MODULE_AUTHOR("Kiyoshi Ueda <k-ueda@ct.jp.nec.com>");
-+MODULE_LICENSE("GPL");
projects / people / pmueller / ipfire-2.x.git / blobdiff