From 66600fb55522d405a68d7340a5680a2633c4237e Mon Sep 17 00:00:00 2001

From: Xavi Hernandez <xhernandez@redhat.com>

Date: Thu, 30 Apr 2020 11:19:01 +0200

Subject: [PATCH 377/379] syncop: improve scaling and implement more tools

The current scaling of the syncop thread pool is not working properly

and can leave some tasks in the run queue more time than necessary

when the maximum number of threads is not reached.

This patch provides a better scaling condition to react faster to

pending work.

Condition variables and sleep in the context of a synctask have also

been implemented. Their purpose is to replace regular condition

variables and sleeps that block synctask threads and prevent other

tasks to be executed.

The new features have been applied to several places in glusterd.

upstream patch: https://review.gluster.org/#/c/glusterfs/+/24396/

> Change-Id: Ic50b7c73c104f9e41f08101a357d30b95efccfbf

> Fixes: #1116

> Signed-off-by: Xavi Hernandez <xhernandez@redhat.com>

Change-Id: Ic50b7c73c104f9e41f08101a357d30b95efccfbf

BUG: 1810516

Signed-off-by: Sanju Rakonde <srakonde@redhta.com>

Reviewed-on: https://code.engineering.redhat.com/gerrit/200409

Tested-by: Sanju Rakonde <srakonde@redhat.com>

Tested-by: RHGS Build Bot <nigelb@redhat.com>

Reviewed-by: Xavi Hernandez Juan <xhernandez@redhat.com>

---

 libglusterfs/src/glusterfs/syncop.h                |  52 +++-

 libglusterfs/src/libglusterfs.sym                  |   7 +

 libglusterfs/src/syncop.c                          | 306 ++++++++++++++++-----

 xlators/cluster/dht/src/dht-rebalance.c            |   2 +-

 xlators/mgmt/glusterd/src/glusterd-op-sm.c         |   9 +-

 xlators/mgmt/glusterd/src/glusterd-proc-mgmt.c     |   2 +-

 .../mgmt/glusterd/src/glusterd-snapshot-utils.c    |   5 +-

 xlators/mgmt/glusterd/src/glusterd-syncop.h        |   2 +-

 xlators/mgmt/glusterd/src/glusterd-utils.c         |  29 +-

 xlators/mgmt/glusterd/src/glusterd.c               |   2 +

 xlators/mgmt/glusterd/src/glusterd.h               |   2 +

 11 files changed, 317 insertions(+), 101 deletions(-)

diff --git a/libglusterfs/src/glusterfs/syncop.h b/libglusterfs/src/glusterfs/syncop.h

index e0f1017..3011b4c 100644

--- a/libglusterfs/src/glusterfs/syncop.h

+++ b/libglusterfs/src/glusterfs/syncop.h

@@ -15,6 +15,7 @@

 #include <sys/time.h>

 #include <pthread.h>

 #include <ucontext.h>

+#include "glusterfs/timer.h"

 #define SYNCENV_PROC_MAX 16

 #define SYNCENV_PROC_MIN 2

@@ -32,6 +33,7 @@

 struct synctask;

 struct syncproc;

 struct syncenv;

+struct synccond;

 typedef int (*synctask_cbk_t)(int ret, call_frame_t *frame, void *opaque);

@@ -55,9 +57,12 @@ struct synctask {

     call_frame_t *opframe;

     synctask_cbk_t synccbk;

     synctask_fn_t syncfn;

-    synctask_state_t state;

+    struct timespec *delta;

+    gf_timer_t *timer;

+    struct synccond *synccond;

     void *opaque;

     void *stack;

+    synctask_state_t state;

     int woken;

     int slept;

     int ret;

@@ -85,19 +90,21 @@ struct syncproc {

 /* hosts the scheduler thread and framework for executing synctasks */

 struct syncenv {

     struct syncproc proc[SYNCENV_PROC_MAX];

-    int procs;

+

+    pthread_mutex_t mutex;

+    pthread_cond_t cond;

     struct list_head runq;

-    int runcount;

     struct list_head waitq;

-    int waitcount;

+

+    int procs;

+    int procs_idle;

+

+    int runcount;

     int procmin;

     int procmax;

-    pthread_mutex_t mutex;

-    pthread_cond_t cond;

-

     size_t stacksize;

     int destroy; /* FLAG to mark syncenv is in destroy mode

@@ -123,6 +130,13 @@ struct synclock {

 };

 typedef struct synclock synclock_t;

+struct synccond {

+    pthread_mutex_t pmutex;

+    pthread_cond_t pcond;

+    struct list_head waitq;

+};

+typedef struct synccond synccond_t;

+

 struct syncbarrier {

     gf_boolean_t initialized; /*Set on successful initialization*/

     pthread_mutex_t guard;    /* guard the remaining members, pair @cond */

@@ -219,7 +233,7 @@ struct syncopctx {

 #define __yield(args)                                                          \

     do {                                                                       \

         if (args->task) {                                                      \

-            synctask_yield(args->task);                                        \

+            synctask_yield(args->task, NULL);                                  \

         } else {                                                               \

             pthread_mutex_lock(&args->mutex);                                  \

             {                                                                  \

@@ -307,7 +321,9 @@ synctask_join(struct synctask *task);

 void

 synctask_wake(struct synctask *task);

 void

-synctask_yield(struct synctask *task);

+synctask_yield(struct synctask *task, struct timespec *delta);

+void

+synctask_sleep(int32_t secs);

 void

 synctask_waitfor(struct synctask *task, int count);

@@ -405,6 +421,24 @@ synclock_trylock(synclock_t *lock);

 int

 synclock_unlock(synclock_t *lock);

+int32_t

+synccond_init(synccond_t *cond);

+

+void

+synccond_destroy(synccond_t *cond);

+

+int

+synccond_wait(synccond_t *cond, synclock_t *lock);

+

+int

+synccond_timedwait(synccond_t *cond, synclock_t *lock, struct timespec *delta);

+

+void

+synccond_signal(synccond_t *cond);

+

+void

+synccond_broadcast(synccond_t *cond);

+

 int

 syncbarrier_init(syncbarrier_t *barrier);

 int

diff --git a/libglusterfs/src/libglusterfs.sym b/libglusterfs/src/libglusterfs.sym

index 467a1b7..5a721e0 100644

--- a/libglusterfs/src/libglusterfs.sym

+++ b/libglusterfs/src/libglusterfs.sym

@@ -938,6 +938,12 @@ syncbarrier_destroy

 syncbarrier_init

 syncbarrier_wait

 syncbarrier_wake

+synccond_init

+synccond_destroy

+synccond_wait

+synccond_timedwait

+synccond_signal

+synccond_broadcast

 syncenv_destroy

 syncenv_new

 synclock_destroy

@@ -1015,6 +1021,7 @@ synctask_new

 synctask_new1

 synctask_set

 synctask_setid

+synctask_sleep

 synctask_wake

 synctask_yield

 sys_access

diff --git a/libglusterfs/src/syncop.c b/libglusterfs/src/syncop.c

index 693970f..71d37b7 100644

--- a/libglusterfs/src/syncop.c

+++ b/libglusterfs/src/syncop.c

@@ -154,10 +154,14 @@ out:

     return ret;

 }

+void *

+syncenv_processor(void *thdata);

+

 static void

 __run(struct synctask *task)

 {

     struct syncenv *env = NULL;

+    int32_t total, ret, i;

     env = task->env;

@@ -173,7 +177,6 @@ __run(struct synctask *task)

             env->runcount--;

             break;

         case SYNCTASK_WAIT:

-            env->waitcount--;

             break;

         case SYNCTASK_DONE:

             gf_msg(task->xl->name, GF_LOG_WARNING, 0, LG_MSG_COMPLETED_TASK,

@@ -187,8 +190,27 @@ __run(struct synctask *task)

     }

     list_add_tail(&task->all_tasks, &env->runq);

-    env->runcount++;

     task->state = SYNCTASK_RUN;

+

+    env->runcount++;

+

+    total = env->procs + env->runcount - env->procs_idle;

+    if (total > env->procmax) {

+        total = env->procmax;

+    }

+    if (total > env->procs) {

+        for (i = 0; i < env->procmax; i++) {

+            if (env->proc[i].env == NULL) {

+                env->proc[i].env = env;

+                ret = gf_thread_create(&env->proc[i].processor, NULL,

+                                       syncenv_processor, &env->proc[i],

+                                       "sproc%d", i);

+                if ((ret < 0) || (++env->procs >= total)) {

+                    break;

+                }

+            }

+        }

+    }

 }

 static void

@@ -210,7 +232,6 @@ __wait(struct synctask *task)

             gf_msg(task->xl->name, GF_LOG_WARNING, 0, LG_MSG_REWAITING_TASK,

                    "re-waiting already waiting "

                    "task");

-            env->waitcount--;

             break;

         case SYNCTASK_DONE:

             gf_msg(task->xl->name, GF_LOG_WARNING, 0, LG_MSG_COMPLETED_TASK,

@@ -223,12 +244,11 @@ __wait(struct synctask *task)

     }

     list_add_tail(&task->all_tasks, &env->waitq);

-    env->waitcount++;

     task->state = SYNCTASK_WAIT;

 }

 void

-synctask_yield(struct synctask *task)

+synctask_yield(struct synctask *task, struct timespec *delta)

 {

     xlator_t *oldTHIS = THIS;

@@ -237,6 +257,8 @@ synctask_yield(struct synctask *task)

     task->proc->sched.uc_flags &= ~_UC_TLSBASE;

 #endif

+    task->delta = delta;

+

     if (task->state != SYNCTASK_DONE) {

         task->state = SYNCTASK_SUSPEND;

     }

@@ -249,6 +271,35 @@ synctask_yield(struct synctask *task)

 }

 void

+synctask_sleep(int32_t secs)

+{

+    struct timespec delta;

+    struct synctask *task;

+

+    task = synctask_get();

+

+    if (task == NULL) {

+        sleep(secs);

+    } else {

+        delta.tv_sec = secs;

+        delta.tv_nsec = 0;

+

+        synctask_yield(task, &delta);

+    }

+}

+

+static void

+__synctask_wake(struct synctask *task)

+{

+    task->woken = 1;

+

+    if (task->slept)

+        __run(task);

+

+    pthread_cond_broadcast(&task->env->cond);

+}

+

+void

 synctask_wake(struct synctask *task)

 {

     struct syncenv *env = NULL;

@@ -257,13 +308,18 @@ synctask_wake(struct synctask *task)

     pthread_mutex_lock(&env->mutex);

     {

-        task->woken = 1;

+        if (task->timer != NULL) {

+            if (gf_timer_call_cancel(task->xl->ctx, task->timer) != 0) {

+                goto unlock;

+            }

-        if (task->slept)

-            __run(task);

+            task->timer = NULL;

+            task->synccond = NULL;

+        }

-        pthread_cond_broadcast(&env->cond);

+        __synctask_wake(task);

     }

+unlock:

     pthread_mutex_unlock(&env->mutex);

 }

@@ -282,7 +338,7 @@ synctask_wrap(void)

     task->state = SYNCTASK_DONE;

-    synctask_yield(task);

+    synctask_yield(task, NULL);

 }

 void

@@ -422,11 +478,6 @@ synctask_create(struct syncenv *env, size_t stacksize, synctask_fn_t fn,

     }

     synctask_wake(newtask);

-    /*

-     * Make sure someone's there to execute anything we just put on the

-     * run queue.

-     */

-    syncenv_scale(env);

     return newtask;

 err:

@@ -520,8 +571,12 @@ syncenv_task(struct syncproc *proc)

                 goto unlock;

             }

+            env->procs_idle++;

+

             sleep_till.tv_sec = time(NULL) + SYNCPROC_IDLE_TIME;

             ret = pthread_cond_timedwait(&env->cond, &env->mutex, &sleep_till);

+

+            env->procs_idle--;

         }

         task = list_entry(env->runq.next, struct synctask, all_tasks);

@@ -540,6 +595,34 @@ unlock:

     return task;

 }

+static void

+synctask_timer(void *data)

+{

+    struct synctask *task = data;

+    struct synccond *cond;

+

+    cond = task->synccond;

+    if (cond != NULL) {

+        pthread_mutex_lock(&cond->pmutex);

+

+        list_del_init(&task->waitq);

+        task->synccond = NULL;

+

+        pthread_mutex_unlock(&cond->pmutex);

+

+        task->ret = -ETIMEDOUT;

+    }

+

+    pthread_mutex_lock(&task->env->mutex);

+

+    gf_timer_call_cancel(task->xl->ctx, task->timer);

+    task->timer = NULL;

+

+    __synctask_wake(task);

+

+    pthread_mutex_unlock(&task->env->mutex);

+}

+

 void

 synctask_switchto(struct synctask *task)

 {

@@ -572,7 +655,14 @@ synctask_switchto(struct synctask *task)

         } else {

             task->slept = 1;

             __wait(task);

+

+            if (task->delta != NULL) {

+                task->timer = gf_timer_call_after(task->xl->ctx, *task->delta,

+                                                  synctask_timer, task);

+            }

         }

+

+        task->delta = NULL;

     }

     pthread_mutex_unlock(&env->mutex);

 }

@@ -580,65 +670,18 @@ synctask_switchto(struct synctask *task)

 void *

 syncenv_processor(void *thdata)

 {

-    struct syncenv *env = NULL;

     struct syncproc *proc = NULL;

     struct synctask *task = NULL;

     proc = thdata;

-    env = proc->env;

-

-    for (;;) {

-        task = syncenv_task(proc);

-        if (!task)

-            break;

+    while ((task = syncenv_task(proc)) != NULL) {

         synctask_switchto(task);

-

-        syncenv_scale(env);

     }

     return NULL;

 }

-void

-syncenv_scale(struct syncenv *env)

-{

-    int diff = 0;

-    int scale = 0;

-    int i = 0;

-    int ret = 0;

-

-    pthread_mutex_lock(&env->mutex);

-    {

-        if (env->procs > env->runcount)

-            goto unlock;

-

-        scale = env->runcount;

-        if (scale > env->procmax)

-            scale = env->procmax;

-        if (scale > env->procs)

-            diff = scale - env->procs;

-        while (diff) {

-            diff--;

-            for (; (i < env->procmax); i++) {

-                if (env->proc[i].processor == 0)

-                    break;

-            }

-

-            env->proc[i].env = env;

-            ret = gf_thread_create(&env->proc[i].processor, NULL,

-                                   syncenv_processor, &env->proc[i],

-                                   "sproc%03hx", env->procs & 0x3ff);

-            if (ret)

-                break;

-            env->procs++;

-            i++;

-        }

-    }

-unlock:

-    pthread_mutex_unlock(&env->mutex);

-}

-

 /* The syncenv threads are cleaned up in this routine.

  */

 void

@@ -715,12 +758,13 @@ syncenv_new(size_t stacksize, int procmin, int procmax)

         newenv->stacksize = stacksize;

     newenv->procmin = procmin;

     newenv->procmax = procmax;

+    newenv->procs_idle = 0;

     for (i = 0; i < newenv->procmin; i++) {

         newenv->proc[i].env = newenv;

         ret = gf_thread_create(&newenv->proc[i].processor, NULL,

                                syncenv_processor, &newenv->proc[i], "sproc%d",

-                               newenv->procs);

+                               i);

         if (ret)

             break;

         newenv->procs++;

@@ -810,7 +854,7 @@ __synclock_lock(struct synclock *lock)

             task->woken = 0;

             list_add_tail(&task->waitq, &lock->waitq);

             pthread_mutex_unlock(&lock->guard);

-            synctask_yield(task);

+            synctask_yield(task, NULL);

             /* task is removed from waitq in unlock,

              * under lock->guard.*/

             pthread_mutex_lock(&lock->guard);

@@ -963,6 +1007,136 @@ synclock_unlock(synclock_t *lock)

     return ret;

 }

+/* Condition variables */

+

+int32_t

+synccond_init(synccond_t *cond)

+{

+    int32_t ret;

+

+    INIT_LIST_HEAD(&cond->waitq);

+

+    ret = pthread_mutex_init(&cond->pmutex, NULL);

+    if (ret != 0) {

+        return -ret;

+    }

+

+    ret = pthread_cond_init(&cond->pcond, NULL);

+    if (ret != 0) {

+        pthread_mutex_destroy(&cond->pmutex);

+    }

+

+    return -ret;

+}

+

+void

+synccond_destroy(synccond_t *cond)

+{

+    pthread_cond_destroy(&cond->pcond);

+    pthread_mutex_destroy(&cond->pmutex);

+}

+

+int

+synccond_timedwait(synccond_t *cond, synclock_t *lock, struct timespec *delta)

+{

+    struct timespec now;

+    struct synctask *task = NULL;

+    int ret;

+

+    task = synctask_get();

+

+    if (task == NULL) {

+        if (delta != NULL) {

+            timespec_now_realtime(&now;;

+            timespec_adjust_delta(&now, *delta);

+        }

+

+        pthread_mutex_lock(&cond->pmutex);

+

+        if (delta == NULL) {

+            ret = -pthread_cond_wait(&cond->pcond, &cond->pmutex);

+        } else {

+            ret = -pthread_cond_timedwait(&cond->pcond, &cond->pmutex, &now;;

+        }

+    } else {

+        pthread_mutex_lock(&cond->pmutex);

+

+        list_add_tail(&task->waitq, &cond->waitq);

+        task->synccond = cond;

+

+        ret = synclock_unlock(lock);

+        if (ret == 0) {

+            pthread_mutex_unlock(&cond->pmutex);

+

+            synctask_yield(task, delta);

+

+            ret = synclock_lock(lock);

+            if (ret == 0) {

+                ret = task->ret;

+            }

+            task->ret = 0;

+

+            return ret;

+        }

+

+        list_del_init(&task->waitq);

+    }

+

+    pthread_mutex_unlock(&cond->pmutex);

+

+    return ret;

+}

+

+int

+synccond_wait(synccond_t *cond, synclock_t *lock)

+{

+    return synccond_timedwait(cond, lock, NULL);

+}

+

+void

+synccond_signal(synccond_t *cond)

+{

+    struct synctask *task;

+

+    pthread_mutex_lock(&cond->pmutex);

+

+    if (!list_empty(&cond->waitq)) {

+        task = list_first_entry(&cond->waitq, struct synctask, waitq);

+        list_del_init(&task->waitq);

+

+        pthread_mutex_unlock(&cond->pmutex);

+

+        synctask_wake(task);

+    } else {

+        pthread_cond_signal(&cond->pcond);

+

+        pthread_mutex_unlock(&cond->pmutex);

+    }

+}

+

+void

+synccond_broadcast(synccond_t *cond)

+{

+    struct list_head list;

+    struct synctask *task;

+

+    INIT_LIST_HEAD(&list);

+

+    pthread_mutex_lock(&cond->pmutex);

+

+    list_splice_init(&cond->waitq, &list);

+    pthread_cond_broadcast(&cond->pcond);

+

+    pthread_mutex_unlock(&cond->pmutex);

+

+    while (!list_empty(&list)) {

+        task = list_first_entry(&list, struct synctask, waitq);

+        list_del_init(&task->waitq);

+

+        synctask_wake(task);

+    }

+}

+

 /* Barriers */

 int

@@ -1032,7 +1206,7 @@ __syncbarrier_wait(struct syncbarrier *barrier, int waitfor)

             /* called within a synctask */

             list_add_tail(&task->waitq, &barrier->waitq);

             pthread_mutex_unlock(&barrier->guard);

-            synctask_yield(task);

+            synctask_yield(task, NULL);

             pthread_mutex_lock(&barrier->guard);

         } else {

             /* called by a non-synctask */

diff --git a/xlators/cluster/dht/src/dht-rebalance.c b/xlators/cluster/dht/src/dht-rebalance.c

index c692119..957deaa 100644

--- a/xlators/cluster/dht/src/dht-rebalance.c

+++ b/xlators/cluster/dht/src/dht-rebalance.c

@@ -5224,7 +5224,7 @@ gf_defrag_pause_tier(xlator_t *this, gf_defrag_info_t *defrag)

     defrag->tier_conf.pause_timer = gf_timer_call_after(

         this->ctx, delta, gf_defrag_pause_tier_timeout, this);

-    synctask_yield(defrag->tier_conf.pause_synctask);

+    synctask_yield(defrag->tier_conf.pause_synctask, NULL);

     if (gf_defrag_get_pause_state(&defrag->tier_conf) == TIER_PAUSED)

         goto out;

diff --git a/xlators/mgmt/glusterd/src/glusterd-op-sm.c b/xlators/mgmt/glusterd/src/glusterd-op-sm.c

index 0d29de2..6475611 100644

--- a/xlators/mgmt/glusterd/src/glusterd-op-sm.c

+++ b/xlators/mgmt/glusterd/src/glusterd-op-sm.c

@@ -6076,13 +6076,8 @@ glusterd_op_stage_validate(glusterd_op_t op, dict_t *dict, char **op_errstr,

 static void

 glusterd_wait_for_blockers(glusterd_conf_t *priv)

 {

-    uint64_t blockers = GF_ATOMIC_GET(priv->blockers);

-

-    while (blockers) {

-        synclock_unlock(&priv->big_lock);

-        sleep(1);

-        blockers = GF_ATOMIC_GET(priv->blockers);

-        synclock_lock(&priv->big_lock);

+    while (GF_ATOMIC_GET(priv->blockers)) {

+        synccond_wait(&priv->cond_blockers, &priv->big_lock);

     }

 }

diff --git a/xlators/mgmt/glusterd/src/glusterd-proc-mgmt.c b/xlators/mgmt/glusterd/src/glusterd-proc-mgmt.c

index 36018a0..f55a5fd 100644

--- a/xlators/mgmt/glusterd/src/glusterd-proc-mgmt.c

+++ b/xlators/mgmt/glusterd/src/glusterd-proc-mgmt.c

@@ -112,7 +112,7 @@ glusterd_proc_stop(glusterd_proc_t *proc, int sig, int flags)

         goto out;

     synclock_unlock(&conf->big_lock);

-    sleep(1);

+    synctask_sleep(1);

     synclock_lock(&conf->big_lock);

     if (gf_is_service_running(proc->pidfile, &pid)) {

         ret = kill(pid, SIGKILL);

diff --git a/xlators/mgmt/glusterd/src/glusterd-snapshot-utils.c b/xlators/mgmt/glusterd/src/glusterd-snapshot-utils.c

index d225854..386eed2 100644

--- a/xlators/mgmt/glusterd/src/glusterd-snapshot-utils.c

+++ b/xlators/mgmt/glusterd/src/glusterd-snapshot-utils.c

@@ -1961,9 +1961,7 @@ glusterd_update_snaps_synctask(void *opaque)

     synclock_lock(&conf->big_lock);

     while (conf->restart_bricks) {

-        synclock_unlock(&conf->big_lock);

-        sleep(2);

-        synclock_lock(&conf->big_lock);

+        synccond_wait(&conf->cond_restart_bricks, &conf->big_lock);