Rework node slab garbage collection to limit blocking work threads

Also remove debug mode from forcing foreground mode

libfuse/lib/fmp.h

@@ -249,6 +249,14 @@ fmp_avail_objs(fmp_t *fmp_)
   return fmp_->avail_objs;
 }
 
+static
+inline
+uint64_t
+fmp_objs_per_slab(fmp_t *fmp_)
+{
+  return (fmp_->slab_size / fmp_->obj_size);
+}
+
 static
 inline
 uint64_t
@@ -256,15 +264,19 @@ fmp_objs_in_slab(fmp_t *fmp_,
                  void  *slab_)
 {
   char *slab;
+  uint64_t objs_per_slab;
   uint64_t objs_in_slab;
 
-  objs_in_slab = 0;
   slab          = (char*)slab_;
+  objs_in_slab  = 0;
+  objs_per_slab = fmp_objs_per_slab(fmp_);
   for(mem_stack_t *stack = fmp_->objs; stack != NULL; stack = stack->next)
     {
       char *obj = (char*)stack;
       if((obj >= slab) && (obj < (slab + fmp_->slab_size)))
         objs_in_slab++;
+      if(objs_in_slab >= objs_per_slab)
+        break;
     }
 
   return objs_in_slab;
@@ -276,17 +288,27 @@ void
 fmp_remove_objs_in_slab(fmp_t *fmp_,
                         void  *slab_)
 {
-  char *slab = (char*)slab_;
-  mem_stack_t **p = &fmp_->objs;
+  char *slab;
+  uint64_t objs_per_slab;
+  uint64_t objs_in_slab;
+  mem_stack_t **p;
 
+  p             = &fmp_->objs;
+  slab          = (char*)slab_;
+  objs_in_slab  = 0;
+  objs_per_slab = fmp_objs_per_slab(fmp_);
   while((*p) != NULL)
     {
       char *obj = (char*)*p;
 
       if((obj >= slab) && (obj < (slab + fmp_->slab_size)))
         {
+          objs_in_slab++;
           *p = (*p)->next;
           fmp_->avail_objs--;
+
+          if(objs_in_slab >= objs_per_slab)
+            break;
           continue;
         }
 
@@ -297,47 +319,40 @@ fmp_remove_objs_in_slab(fmp_t *fmp_,
 static
 inline
 int
-fmp_gc(fmp_t *fmp_)
+fmp_gc_slab(fmp_t    *fmp_,
+            uint64_t  slab_idx_)
 {
-  int i;
-  int freed_slabs;
-  uint64_t objs_per_slab;
-
-  objs_per_slab = (fmp_->slab_size / fmp_->obj_size);
-
-  i = 0;
-  freed_slabs = 0;
-  while(i < kv_size(fmp_->slabs))
-    {
   char *slab;
   uint64_t objs_in_slab;
+  uint64_t objs_per_slab;
 
-      slab = kv_A(fmp_->slabs,i);
+  slab_idx_ = (slab_idx_ % kv_size(fmp_->slabs));
 
+  slab = kv_A(fmp_->slabs,slab_idx_);
+
+  objs_per_slab = fmp_objs_per_slab(fmp_);
   objs_in_slab  = fmp_objs_in_slab(fmp_,slab);
   if(objs_in_slab != objs_per_slab)
-        {
-          i++;
-          continue;
-        }
+    return 0;
 
   fmp_remove_objs_in_slab(fmp_,slab);
-
-      kv_delete(fmp_->slabs,i);
-
+  kv_delete(fmp_->slabs,slab_idx_);
   fmp_slab_free_mmap(fmp_,slab);
-      freed_slabs++;
-    }
 
-  return freed_slabs;
+  return 1;
 }
 
+
 static
 inline
-uint64_t
-fmp_objs_per_slab(fmp_t *fmp_)
+int
+fmp_gc(fmp_t *fmp_)
 {
-  return (fmp_->slab_size / fmp_->obj_size);
+  uint64_t slab_idx;
+
+  slab_idx = rand();
+
+  return fmp_gc_slab(fmp_,slab_idx);
 }
 
 static
@@ -345,14 +360,15 @@ inline
 double
 fmp_slab_usage_ratio(fmp_t *fmp_)
 {
-  double rv;
-  uint64_t objs_per_slab;
+  double avail_objs;
+  double objs_per_slab;
+  double nums_of_slabs;
 
+  avail_objs    = fmp_->avail_objs;
   objs_per_slab = fmp_objs_per_slab(fmp_);
+  nums_of_slabs = kv_size(fmp_->slabs);
 
-  rv = ((double)fmp_->avail_objs / (double)objs_per_slab);
-
-  return rv;
+  return (avail_objs / (objs_per_slab * nums_of_slabs));
 }
 
 static

libfuse/lib/fuse.c

@@ -62,6 +62,7 @@ struct fuse_config
   unsigned int umask;
   int remember;
   int debug;
+  int nogc;
   int use_ino;
   int set_mode;
   int set_uid;
@@ -3903,6 +3904,7 @@ static const struct fuse_opt fuse_lib_opts[] =
    FUSE_OPT_KEY("-d",		      FUSE_OPT_KEY_KEEP),
    FUSE_LIB_OPT("debug",	      debug,1),
    FUSE_LIB_OPT("-d",		      debug,1),
+   FUSE_LIB_OPT("nogc",               nogc,1),
    FUSE_LIB_OPT("umask=",	      set_mode,1),
    FUSE_LIB_OPT("umask=%o",	      umask,0),
    FUSE_LIB_OPT("uid=",	      set_uid,1),
@@ -4002,9 +4004,10 @@ void
 metrics_log_nodes_info(struct fuse *f_,
                        FILE        *file_)
 {
-  pthread_mutex_lock(&f_->lock);
+  char buf[1024];
 
-  fprintf(file_,
+  pthread_mutex_lock(&f_->lock);
+  snprintf(buf,sizeof(buf),
            "time: %zu\n"
            "sizeof(node): %zu\n"
            "node id_table size: %zu\n"
@@ -4032,8 +4035,9 @@ metrics_log_nodes_info(struct fuse *f_,
            lfmp_avail_objs(&f_->node_fmp),
            lfmp_total_allocated_memory(&f_->node_fmp)
            );
-
   pthread_mutex_unlock(&f_->lock);
+
+  fputs(buf,file_);
 }
 
 static
@@ -4068,11 +4072,13 @@ static
 void*
 fuse_maintenance_loop(void *fuse_)
 {
+  int gc;
   int loops;
   int sleep_time;
   double slab_usage_ratio;
   struct fuse *f = (struct fuse*)fuse_;
 
+  gc = 0;
   loops = 0;
   sleep_time = 60;
   while(1)
@@ -4080,12 +4086,15 @@ fuse_maintenance_loop(void *fuse_)
       if(remember_nodes(f))
         fuse_prune_remembered_nodes(f);
 
-      slab_usage_ratio = lfmp_slab_usage_ratio(&f->node_fmp);
-      if(slab_usage_ratio > 3.0)
-        lfmp_gc(&f->node_fmp);
-
-      if(loops % 15)
+      if((loops % 15) == 0)
+        {
           fuse_malloc_trim();
+          gc = 1;
+        }
+
+      // Trigger a followup gc if this gc succeeds
+      if(!f->conf.nogc && gc)
+        gc = lfmp_gc(&f->node_fmp);
 
       if(g_LOG_METRICS)
         metrics_log_nodes_info_to_tmp_dir(f);

libfuse/lib/helper.c

@@ -40,8 +40,6 @@ static
 const
 struct fuse_opt fuse_helper_opts[] =
   {
-    FUSE_HELPER_OPT("-d",	foreground),
-    FUSE_HELPER_OPT("debug",	foreground),
     FUSE_HELPER_OPT("-f",	foreground),
     FUSE_HELPER_OPT("fsname=",	nodefault_subtype),
     FUSE_HELPER_OPT("subtype=",	nodefault_subtype),