Merge pull request xapi-project#3136 from Frezzle/SCTX-2565

CA-258652/SCTX-2565: Get initial host memory from squeezed

Author: Frezzle

ocaml/xapi/dbsync_slave.ml

@@ -140,17 +140,16 @@ let record_host_memory_properties ~__context =
 
   let metrics = Db.Host.get_metrics ~__context ~self in
   Db.Host_metrics.set_memory_total ~__context ~self:metrics ~value:total_memory_bytes;
-  let boot_memory_file = Xapi_globs.initial_host_free_memory_file in
-  let boot_memory_string =
+  let boot_memory_bytes =
     try
-      Some (Unixext.string_of_file boot_memory_file)
+      let dbg = Context.string_of_task __context in
+      Some (Memory_client.Client.get_host_initial_free_memory dbg)
     with e ->
-      warn "Could not read host free memory file. This may prevent \
-            			VMs from being started on this host. (%s)" (Printexc.to_string e);
+      warn "Failed to get host free memory from ballooning service. This may \
+        prevent VMs from being started on this host. (%s)" (Printexc.to_string e);
       None in
   maybe
-    (fun boot_memory_string ->
-       let boot_memory_bytes = Int64.of_string boot_memory_string in
+    (fun boot_memory_bytes ->
        (* Host memory overhead comes from multiple sources:         *)
        (* 1. obvious overhead: (e.g. Xen, crash kernel).            *)
        (*    appears as used memory.                                *)
@@ -174,7 +173,7 @@ let record_host_memory_properties ~__context =
        Db.Host.set_memory_overhead ~__context ~self ~value:
          (obvious_overhead_memory_bytes ++ nonobvious_overhead_memory_bytes);
     )
-    boot_memory_string
+    boot_memory_bytes
 
 (* -- used this for testing uniqueness constraints executed on slave do not kill connection.
    Committing commented out vsn of this because it might be useful again..

ocaml/xapi/xapi.ml

@@ -482,50 +482,6 @@ let resynchronise_ha_state () =
     (* Critical that we don't continue as a master and use shared resources *)
     error "Caught exception resynchronising state of HA system: %s" (ExnHelper.string_of_exn e)
 
-(* Calculates the amount of free memory on the host at boot time. *)
-(* Returns a result that is equivalent to (T - X), where:         *)
-(*     T = total memory in host.                                  *)
-(*     X = host virtualization overhead:                          *)
-(*         memory used by Xen code, heap and crash kernel.        *)
-(* Actually returns the current value of (F + S + Z), where:      *)
-(*     F = host free memory.                                      *)
-(*     S = host scrub memory.                                     *)
-(*     Z = host memory used by domain 0.                          *)
-(* This relies on the equivalence (T = X + F + S + Z).            *)
-(* Warning! This function assumes that:                           *)
-(*     1. Domain 0 is currently in an unballooned state.          *)
-(*     2. No other domains have been started.                     *)
-let calculate_boot_time_host_free_memory () =
-  let ( + ) = Nativeint.add in
-  let open Xenctrl in
-  let host_info = with_intf (fun xc -> physinfo xc) in
-  let host_free_pages = host_info.free_pages in
-  let host_scrub_pages = host_info.scrub_pages in
-  match Create_misc.read_dom0_memory_usage () with
-  | None -> failwith "can't query balloon driver"
-  | Some domain0_bytes ->
-    let domain0_total_pages = XenopsMemory.pages_of_bytes_used domain0_bytes in
-    let boot_time_host_free_pages =
-      host_free_pages + host_scrub_pages + (Int64.to_nativeint domain0_total_pages) in
-    let boot_time_host_free_kib =
-      pages_to_kib (Int64.of_nativeint boot_time_host_free_pages) in
-    Int64.mul 1024L boot_time_host_free_kib
-
-(* Read the free memory on the host and record this in the db. This is used *)
-(* as the baseline for memory calculations in the message forwarding layer. *)
-let record_boot_time_host_free_memory () =
-  if not (Unixext.file_exists Xapi_globs.initial_host_free_memory_file) then begin
-    try
-      let free_memory = calculate_boot_time_host_free_memory () in
-      Unixext.mkdir_rec (Filename.dirname Xapi_globs.initial_host_free_memory_file) 0o700;
-      Unixext.write_string_to_file
-        Xapi_globs.initial_host_free_memory_file
-        (Int64.to_string free_memory)
-    with e ->
-      error "Could not record host free memory. This may prevent VMs from being started on this host. (%s)"
-        (Printexc.to_string e)
-  end
-
 (** Reset the networking-related metadata for this host if the command [xe-reset-networking]
  *  was executed before the restart. *)
 let check_network_reset () =

ocaml/xapi/xapi_globs.ml

@@ -86,7 +86,6 @@ let http_realm = "xapi"
 let log_config_file = ref (Filename.concat "/etc/xensource" "log.conf")
 let remote_db_conf_fragment_path = ref (Filename.concat "/etc/xensource" "remote.db.conf")
 let cpu_info_file = ref (Filename.concat "/etc/xensource" "boot_time_cpus")
-let initial_host_free_memory_file = "/var/run/nonpersistent/xapi/boot_time_memory"
 let requires_reboot_file = "/var/run/nonpersistent/xapi/host-requires-reboot"
 let using_rrds = ref false
 

ocaml/xapi/xapi_main.ml

@@ -36,7 +36,4 @@ let _ =
   Stdext.Unixext.mkdir_rec (Filename.concat "/var/lib/xcp" "debug") 0o700;
   Unix.chdir (Filename.concat "/var/lib/xcp" "debug");
 
-  (* WARNING! Never move this function call into the list of startup tasks. *)
-  record_boot_time_host_free_memory ();
-
   watchdog server_init