dht/rebalance: Throttle rebalance

Throttle value will be "normal" by default. For throttling down,
a thread will be put in to sleep. And for throttling up,
gf_defrag_process_dir will wake up the sleeping threads.

Change-Id: I74d530e3effd6e60e6eec81ccc8ff65789fa9c13
Signed-off-by: Susant Palai <spalai@redhat.com>
Reviewed-on: http://review.gluster.org/10526
Reviewed-by: Raghavendra G <rgowdapp@redhat.com>
Tested-by: Raghavendra G <rgowdapp@redhat.com>

3 files changed, 133 insertions, 4 deletions

diff --git a/xlators/cluster/dht/src/dht-common.h b/xlators/cluster/dht/src/dht-common.h
index baf244d0564..3e2d5d725e9 100644
--- a/xlators/cluster/dht/src/dht-common.h
+++ b/xlators/cluster/dht/src/dht-common.h
@@ -346,6 +346,13 @@ struct gf_defrag_info_ {
         int32_t                      abort;
         int32_t                      wakeup_crawler;
 
+        /*Throttle params*/
+        /*stands for reconfigured thread count*/
+        int32_t                      recon_thread_count;
+        /*stands for current running thread count*/
+        int32_t                      current_thread_count;
+        pthread_cond_t               df_wakeup_thread;
+
         /* Hard link handle requirement */
         synclock_t                   link_lock;
 };
@@ -421,6 +428,7 @@ struct dht_conf {
         /* Support size-weighted rebalancing (heterogeneous bricks). */
         gf_boolean_t    do_weighting;
         gf_boolean_t    randomize_by_gfid;
+        char           *dthrottle;
 
         dht_methods_t  *methods;
 
diff --git a/xlators/cluster/dht/src/dht-rebalance.c b/xlators/cluster/dht/src/dht-rebalance.c
index e97e3916fd7..0a29ba30d3d 100644
--- a/xlators/cluster/dht/src/dht-rebalance.c
+++ b/xlators/cluster/dht/src/dht-rebalance.c
@@ -19,14 +19,17 @@
 #include <signal.h>
 #include <fnmatch.h>
 #include <signal.h>
+#include <sys/sysinfo.h>
 
 #define GF_DISK_SECTOR_SIZE             512
 #define DHT_REBALANCE_PID               4242 /* Change it if required */
 #define DHT_REBALANCE_BLKSIZE           (128 * 1024)
-#define MAX_MIGRATOR_THREAD_COUNT       20
+#define MAX_MIGRATOR_THREAD_COUNT       40
 #define MAX_MIGRATE_QUEUE_COUNT         500
 #define MIN_MIGRATE_QUEUE_COUNT         200
 
+#define MAX(a, b) (((a) > (b))?(a):(b))
+
 #define GF_CRAWL_INDEX_MOVE(idx, sv_cnt)  {     \
                 idx++;                          \
                 idx %= sv_cnt;                  \
@@ -1724,6 +1727,36 @@ gf_defrag_task (void *opaque)
 
                 pthread_mutex_lock (&defrag->dfq_mutex);
                 {
+
+                        /*Throttle down:
+                          If the reconfigured count is less than current thread
+                          count, then the current thread will sleep */
+
+                        /*TODO: Need to refactor the following block to work
+                         *under defrag->lock. For now access
+                         * defrag->current_thread_count and rthcount under
+                         * dfq_mutex lock */
+                        while (!defrag->crawl_done &&
+                              (defrag->recon_thread_count <
+                                        defrag->current_thread_count)) {
+                                defrag->current_thread_count--;
+                                gf_log ("DHT", GF_LOG_INFO,
+                                        "Thread sleeping. "
+                                        "defrag->current_thread_count: %d",
+                                         defrag->current_thread_count);
+
+                                pthread_cond_wait (
+                                           &defrag->df_wakeup_thread,
+                                           &defrag->dfq_mutex);
+
+                                defrag->current_thread_count++;
+
+                                gf_log ("DHT", GF_LOG_INFO,
+                                        "Thread wokeup. "
+                                        "defrag->current_thread_count: %d",
+                                         defrag->current_thread_count);
+                        }
+
                         if (defrag->q_entry_count) {
                                 iterator = list_entry (q_head->next,
                                                 typeof(*iterator), list);
@@ -2067,9 +2100,11 @@ gf_defrag_process_dir (xlator_t *this, gf_defrag_info_t *defrag, loc_t *loc,
         double                   elapsed           = {0,};
         int                      local_subvols_cnt = 0;
         int                      i                 = 0;
+        int                      j                 = 0;
         struct  dht_container   *container         = NULL;
         int                      ldfq_count        = 0;
         int                      dfc_index         = 0;
+        int                      throttle_up       = 0;
         struct dir_dfmeta       *dir_dfmeta        = NULL;
 
         gf_log (this->name, GF_LOG_INFO, "migrate data called on %s",
@@ -2197,6 +2232,25 @@ gf_defrag_process_dir (xlator_t *this, gf_defrag_info_t *defrag, loc_t *loc,
 
                 pthread_mutex_lock (&defrag->dfq_mutex);
                 {
+
+                      /*Throttle up: If reconfigured count is higher than
+                        current thread count, wake up the sleeping threads
+                        TODO: Need to refactor this. Instead of making the
+                        thread sleep and wake, we should terminate and spawn
+                        threads on-demand*/
+
+                        if (defrag->recon_thread_count >
+                                         defrag->current_thread_count) {
+                                throttle_up =
+                                        (defrag->recon_thread_count -
+                                            defrag->current_thread_count);
+                                for (j = 0; j < throttle_up; j++) {
+                                        pthread_cond_signal (
+                                             &defrag->df_wakeup_thread);
+                                }
+
+                        }
+
                         while (defrag->q_entry_count >
                                         MAX_MIGRATE_QUEUE_COUNT) {
                                 defrag->wakeup_crawler = 1;
@@ -2473,6 +2527,7 @@ gf_defrag_start_crawl (void *data)
         int                      i              = 0;
         int                     thread_index    = 0;
         int                     err             = 0;
+        int                     thread_spawn_count = 0;
         pthread_t tid[MAX_MIGRATOR_THREAD_COUNT];
 
         this = data;
@@ -2585,8 +2640,15 @@ gf_defrag_start_crawl (void *data)
 
                 INIT_LIST_HEAD (&(defrag->queue[0].list));
 
+                thread_spawn_count = MAX ((get_nprocs() - 4), 4);
+
+                gf_log (this->name, GF_LOG_DEBUG, "thread_spawn_count: %d",
+                        thread_spawn_count);
+
+                defrag->current_thread_count = thread_spawn_count;
+
                 /*Spawn Threads Here*/
-                while (thread_index < MAX_MIGRATOR_THREAD_COUNT) {
+                while (thread_index < thread_spawn_count) {
                         err = pthread_create(&(tid[thread_index]), NULL,
                                      &gf_defrag_task, (void *)defrag);
                         if (err != 0) {
@@ -2651,6 +2713,8 @@ out:
 
                 pthread_cond_broadcast (
                         &defrag->parallel_migration_cond);
+                pthread_cond_broadcast (
+                        &defrag->df_wakeup_thread);
         }
         pthread_mutex_unlock (&defrag->dfq_mutex);
 
diff --git a/xlators/cluster/dht/src/dht-shared.c b/xlators/cluster/dht/src/dht-shared.c
index 3b22a2a8486..0ab81c37890 100644
--- a/xlators/cluster/dht/src/dht-shared.c
+++ b/xlators/cluster/dht/src/dht-shared.c
@@ -15,11 +15,32 @@
 #endif
 
 /* TODO: add NS locking */
-
+#include <sys/sysinfo.h>
 #include "statedump.h"
 #include "dht-common.h"
 #include "dht-messages.h"
 
+#define MAX(a, b) (((a) > (b))?(a):(b))
+
+#define GF_DECIDE_DEFRAG_THROTTLE_COUNT(throttle_count, conf) {         \
+                                                                        \
+                pthread_mutex_lock (&conf->defrag->dfq_mutex);          \
+                                                                        \
+                if (!strcasecmp (conf->dthrottle, "lazy"))              \
+                        conf->defrag->recon_thread_count = 1;           \
+                                                                        \
+                throttle_count = MAX ((get_nprocs() - 4), 4);           \
+                                                                        \
+                if (!strcasecmp (conf->dthrottle, "normal"))            \
+                        conf->defrag->recon_thread_count =              \
+                                                 (throttle_count / 2);  \
+                                                                        \
+                if (!strcasecmp (conf->dthrottle, "aggressive"))        \
+                        conf->defrag->recon_thread_count =              \
+                                                 throttle_count;        \
+                                                                        \
+                pthread_mutex_unlock (&conf->defrag->dfq_mutex);        \
+        }                                                               \
 
 /* TODO:
    - use volumename in xattr instead of "dht"
@@ -374,6 +395,7 @@ dht_reconfigure (xlator_t *this, dict_t *options)
         char            *temp_str = NULL;
         gf_boolean_t     search_unhashed;
         int              ret = -1;
+        int              throttle_count = 0;
 
         GF_VALIDATE_OR_GOTO ("dht", this, out);
         GF_VALIDATE_OR_GOTO ("dht", options, out);
@@ -426,6 +448,16 @@ dht_reconfigure (xlator_t *this, dict_t *options)
                           conf->randomize_by_gfid,
                           options, bool, out);
 
+        GF_OPTION_RECONF ("rebal-throttle", conf->dthrottle, options,
+                          str, out);
+
+        if (conf->defrag) {
+                GF_DECIDE_DEFRAG_THROTTLE_COUNT (throttle_count, conf);
+                gf_log ("DHT", GF_LOG_INFO, "conf->dthrottle: %s, "
+                        "conf->defrag->recon_thread_count: %d",
+                         conf->dthrottle, conf->defrag->recon_thread_count);
+        }
+
         if (conf->defrag) {
                 GF_OPTION_RECONF ("rebalance-stats", conf->defrag->stats,
                                   options, bool, out);
@@ -534,7 +566,7 @@ dht_init (xlator_t *this)
         gf_defrag_info_t                *defrag         = NULL;
         int                              cmd            = 0;
         char                            *node_uuid      = NULL;
-
+        int                              throttle_count = 0;
 
         GF_VALIDATE_OR_GOTO ("dht", this, err);
 
@@ -604,6 +636,8 @@ dht_init (xlator_t *this)
                 pthread_mutex_init (&defrag->dfq_mutex, 0);
                 pthread_cond_init  (&defrag->parallel_migration_cond, 0);
                 pthread_cond_init  (&defrag->rebalance_crawler_alarm, 0);
+                pthread_cond_init  (&defrag->df_wakeup_thread, 0);
+
                 defrag->global_error = 0;
 
         }
@@ -710,6 +744,17 @@ dht_init (xlator_t *this)
         GF_OPTION_INIT ("randomize-hash-range-by-gfid",
                         conf->randomize_by_gfid, bool, err);
 
+        if (defrag) {
+                GF_OPTION_INIT ("rebal-throttle",
+                                 conf->dthrottle, str, err);
+
+                GF_DECIDE_DEFRAG_THROTTLE_COUNT(throttle_count, conf);
+
+                gf_log ("DHT", GF_LOG_DEBUG, "conf->dthrottle: %s, "
+                        "conf->defrag->recon_thread_count: %d",
+                         conf->dthrottle, conf->defrag->recon_thread_count);
+        }
+
         GF_OPTION_INIT ("xattr-name", conf->xattr_name, str, err);
         gf_asprintf (&conf->link_xattr_name, "%s."DHT_LINKFILE_STR,
                      conf->xattr_name);
@@ -922,5 +967,17 @@ struct volume_options options[] = {
           "subvolume to which it hashes"
         },
 
+        { .key =  {"rebal-throttle"},
+          .type = GF_OPTION_TYPE_STR,
+          .default_value = "normal",
+          .description = " Sets the maximum number of parallel file migrations "
+                         "allowed on a node during the rebalance operation. The"
+                         " default value is normal and allows a max of "
+                         "[($(processing units) - 4) / 2), 2]  files to be "
+                         "migrated at a time. Lazy will allow only one file to "
+                         "be migrated at a time and aggressive will allow "
+                         "max of [($(processing units) - 4) / 2), 4]"
+        },
+
         { .key  = {NULL} },
 };