Add option to log node memory usage metrics

libfuse/include/fuse.h

@@ -694,6 +694,8 @@ int fuse_main_real(int argc, char *argv[], const struct fuse_operations *op, siz
 int  fuse_start_maintenance_thread(struct fuse *fuse);
 void fuse_stop_maintenance_thread(struct fuse *fuse);
 
+void fuse_log_metrics(int enabled);
+
 /**
  * Iterate over cache removing stale entries
  * use in conjunction with "-oremember"

libfuse/lib/fmp.h

@@ -354,3 +354,11 @@ fmp_slab_usage_ratio(fmp_t *fmp_)
 
   return rv;
 }
+
+static
+inline
+uint64_t
+fmp_total_allocated_memory(fmp_t *fmp_)
+{
+  return (fmp_->slab_size * kv_size(fmp_->slabs));
+}

libfuse/lib/fuse.c

@@ -53,6 +53,8 @@
 
 #define NODE_TABLE_MIN_SIZE 8192
 
+static int g_LOG_METRICS = 0;
+
 struct fuse_config
 {
   unsigned int uid;
@@ -4006,6 +4008,64 @@ node_table_init(struct node_table *t)
   return 0;
 }
 
+static
+void
+metrics_log_nodes_info(struct fuse *f_,
+                       FILE        *file_)
+{
+  pthread_mutex_lock(&f_->lock);
+
+  fprintf(file_,
+          "time: %zu\n"
+          "sizeof(node): %zu\n"
+          "node id_table size: %zu\n"
+          "node id_table usage: %zu\n"
+          "node id_table total allocated memory: %zu\n"
+          "node name_table size: %zu\n"
+          "node name_table usage: %zu\n"
+          "node name_table total allocated memory: %zu\n"
+          "node memory pool slab count: %zu\n"
+          "node memory pool usage ratio: %f\n"
+          "node memory pool avail objs: %zu\n"
+          "node memory pool total allocated memory: %zu\n"
+          "\n"
+          ,
+          time(NULL),
+          sizeof(struct node),
+          f_->id_table.size,
+          f_->id_table.use,
+          (f_->id_table.size * sizeof(struct node*)),
+          f_->name_table.size,
+          f_->name_table.use,
+          (f_->name_table.size * sizeof(struct node*)),
+          lfmp_slab_count(&f_->node_fmp),
+          lfmp_slab_usage_ratio(&f_->node_fmp),
+          lfmp_avail_objs(&f_->node_fmp),
+          lfmp_total_allocated_memory(&f_->node_fmp)
+          );
+
+  pthread_mutex_unlock(&f_->lock);
+}
+
+static
+void
+metrics_log_nodes_info_to_tmp_dir(struct fuse *f_)
+{
+  FILE *file;
+  char filepath[256];
+
+  sprintf(filepath,"/tmp/mergerfs.%d.info",getpid());
+
+  file = fopen(filepath,"w");
+  if(file == NULL)
+    return;
+
+  metrics_log_nodes_info(f_,file);
+
+  fclose(file);
+}
+
+
 static
 void
 fuse_malloc_trim(void)
@@ -4038,6 +4098,9 @@ fuse_maintenance_loop(void *fuse_)
       if(loops % 15)
         fuse_malloc_trim();
 
+      if(g_LOG_METRICS)
+        metrics_log_nodes_info_to_tmp_dir(f);
+
       loops++;
       sleep(sleep_time);
     }
@@ -4097,6 +4160,8 @@ fuse_new_common(struct fuse_chan             *ch,
   if(fuse_opt_parse(args,&f->conf,fuse_lib_opts,fuse_lib_opt_proc) == -1)
     goto out_free_fs;
 
+  g_LOG_METRICS = f->conf.debug;
+
   f->se = fuse_lowlevel_new_common(args,&llop,sizeof(llop),f);
   if(f->se == NULL)
     goto out_free_fs;
@@ -4215,3 +4280,9 @@ fuse_config_num_threads(const struct fuse *fuse_)
 {
   return fuse_->conf.threads;
 }
+
+void
+fuse_log_metrics(int log_)
+{
+  g_LOG_METRICS = log_;
+}

libfuse/lib/lfmp.h

@@ -211,3 +211,17 @@ lfmp_slab_usage_ratio(lfmp_t *lfmp_)
 
   return rv;
 }
+
+static
+inline
+uint64_t
+lfmp_total_allocated_memory(lfmp_t *lfmp_)
+{
+  uint64_t rv;
+
+  pthread_mutex_lock(&lfmp_->lock);
+  rv = fmp_total_allocated_memory(&lfmp_->fmp);
+  pthread_mutex_unlock(&lfmp_->lock);
+
+  return rv;
+}

src/fuse_ioctl.cpp

@@ -38,10 +38,19 @@
 using std::string;
 using std::vector;
 
+#ifndef _IOC_TYPE
+#define _IOC_TYPE(X) (((X) >> 8) & 0xFF)
+#endif
+
 typedef char IOCTL_BUF[4096];
 #define IOCTL_APP_TYPE 0xDF
-//#define IOCTL_FILE_INFO 0xD000DF00
-#define IOCTL_FILE_INFO _IOWR(IOCTL_APP_TYPE,0,IOCTL_BUF)
+#define IOCTL_FILE_INFO       _IOWR(IOCTL_APP_TYPE,0,IOCTL_BUF)
+#define IOCTL_METRICS_ENABLE  _IOWR(IOCTL_APP_TYPE,1,IOCTL_BUF)
+#define IOCTL_METRICS_DISABLE _IOWR(IOCTL_APP_TYPE,2,IOCTL_BUF)
+
+static_assert(IOCTL_FILE_INFO       == 0xD000DF00,"");
+static_assert(IOCTL_METRICS_ENABLE  == 0xD000DF01,"");
+static_assert(IOCTL_METRICS_DISABLE == 0xD000DF02,"");
 
 #ifndef FS_IOC_GETFLAGS
 # define FS_IOC_GETFLAGS _IOR('f',1,long)
@@ -305,6 +314,34 @@ namespace l
 
     return -ENOATTR;
   }
+
+  static
+  bool
+  is_mergerfs_ioctl_cmd(const unsigned long cmd_)
+  {
+    return (_IOC_TYPE(cmd_) == IOCTL_APP_TYPE);
+  }
+
+  static
+  int
+  ioctl_custom(const fuse_file_info_t *ffi_,
+               unsigned long           cmd_,
+               void                   *data_)
+  {
+    switch(cmd_)
+      {
+      case IOCTL_FILE_INFO:
+        return l::file_info(ffi_,data_);
+      case IOCTL_METRICS_ENABLE:
+        fuse_log_metrics(1);
+        return 0;
+      case IOCTL_METRICS_DISABLE:
+        fuse_log_metrics(0);
+        return 0;
+      }
+
+    return -ENOTTY;
+  }
 }
 
 namespace FUSE
@@ -317,11 +354,8 @@ namespace FUSE
         void                   *data_,
         uint32_t               *out_bufsz_)
   {
-    switch(cmd_)
-      {
-      case IOCTL_FILE_INFO:
-        return l::file_info(ffi_,data_);
-      }
+    if(l::is_mergerfs_ioctl_cmd(cmd_))
+      return l::ioctl_custom(ffi_,cmd_,data_);
 
     if(flags_ & FUSE_IOCTL_DIR)
       return l::ioctl_dir(ffi_,cmd_,data_,out_bufsz_);