From f47eec19ea8dd0f693755cf42e4962e3ec43b06b Mon Sep 17 00:00:00 2001

From: David Gibson <dgibson@redhat.com>

Date: Thu, 16 Nov 2017 03:07:25 +0100

Subject: [PATCH 21/30] memory: Share FlatView's and dispatch trees between

 address spaces

RH-Author: David Gibson <dgibson@redhat.com>

Message-id: <20171116030732.8560-16-dgibson@redhat.com>

Patchwork-id: 77707

O-Subject: [PATCH 15/22] memory: Share FlatView's and dispatch trees between address spaces

Bugzilla: 1481593

RH-Acked-by: Thomas Huth <thuth@redhat.com>

RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>

RH-Acked-by: Eduardo Habkost <ehabkost@redhat.com>

RH-Acked-by: Laurent Vivier <lvivier@redhat.com>

From: Alexey Kardashevskiy <aik@ozlabs.ru>

This allows sharing flat views between address spaces (AS) when

the same root memory region is used when creating a new address space.

This is done by walking through all ASes and caching one FlatView per

a physical root MR (i.e. not aliased).

This removes search for duplicates from address_space_init_shareable() as

FlatViews are shared elsewhere and keeping as::ref_count correct seems

an unnecessary and useless complication.

This should cause no change and memory use or boot time yet.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>

Message-Id: <20170921085110.25598-13-aik@ozlabs.ru>

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

(cherry picked from commit 967dc9b1194a9281124b2e1ce67b6c3359a2138f)

Signed-off-by: David Gibson <dgibson@redhat.com>

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

---

 memory.c | 56 +++++++++++++++++++++++++++++++++++++++++++++-----------

 1 file changed, 45 insertions(+), 11 deletions(-)

diff --git a/memory.c b/memory.c

index 1f58d29..f0c8642 100644

--- a/memory.c

+++ b/memory.c

@@ -47,6 +47,8 @@ static QTAILQ_HEAD(memory_listeners, MemoryListener) memory_listeners

 static QTAILQ_HEAD(, AddressSpace) address_spaces

     = QTAILQ_HEAD_INITIALIZER(address_spaces);

+static GHashTable *flat_views;

+

 typedef struct AddrRange AddrRange;

 /*

@@ -760,6 +762,7 @@ static FlatView *generate_memory_topology(MemoryRegion *mr)

         flatview_add_to_dispatch(view, &mrs);

     }

     address_space_dispatch_compact(view->dispatch);

+    g_hash_table_replace(flat_views, mr, view);

     return view;

 }

@@ -929,11 +932,47 @@ static void address_space_update_topology_pass(AddressSpace *as,

     }

 }

-static void address_space_update_topology(AddressSpace *as)

+static void flatviews_init(void)

+{

+    if (flat_views) {

+        return;

+    }

+

+    flat_views = g_hash_table_new_full(g_direct_hash, g_direct_equal, NULL,

+                                       (GDestroyNotify) flatview_unref);

+}

+

+static void flatviews_reset(void)

+{

+    AddressSpace *as;

+

+    if (flat_views) {

+        g_hash_table_unref(flat_views);

+        flat_views = NULL;

+    }

+    flatviews_init();

+

+    /* Render unique FVs */

+    QTAILQ_FOREACH(as, &address_spaces, address_spaces_link) {

+        MemoryRegion *physmr = memory_region_get_flatview_root(as->root);

+

+        if (g_hash_table_lookup(flat_views, physmr)) {

+            continue;

+        }

+

+        generate_memory_topology(physmr);

+    }

+}

+

+static void address_space_set_flatview(AddressSpace *as)

 {

     FlatView *old_view = address_space_get_flatview(as);

-    MemoryRegion *physmr = memory_region_get_flatview_root(old_view->root);

-    FlatView *new_view = generate_memory_topology(physmr);

+    MemoryRegion *physmr = memory_region_get_flatview_root(as->root);

+    FlatView *new_view = g_hash_table_lookup(flat_views, physmr);

+

+    assert(new_view);

+

+    flatview_ref(new_view);

     if (!QTAILQ_EMPTY(&as->listeners)) {

         address_space_update_topology_pass(as, old_view, new_view, false);

@@ -969,10 +1008,12 @@ void memory_region_transaction_commit(void)

     --memory_region_transaction_depth;

     if (!memory_region_transaction_depth) {

         if (memory_region_update_pending) {

+            flatviews_reset();

+

             MEMORY_LISTENER_CALL_GLOBAL(begin, Forward);

             QTAILQ_FOREACH(as, &address_spaces, address_spaces_link) {

-                address_space_update_topology(as);

+                address_space_set_flatview(as);

                 address_space_update_ioeventfds(as);

             }

             memory_region_update_pending = false;

@@ -2695,13 +2736,6 @@ AddressSpace *address_space_init_shareable(MemoryRegion *root, const char *name)

 {

     AddressSpace *as;

-    QTAILQ_FOREACH(as, &address_spaces, address_spaces_link) {

-        if (root == as->root && as->malloced) {

-            as->ref_count++;

-            return as;

-        }

-    }

-

     as = g_malloc0(sizeof *as);

     address_space_init(as, root, name);

     as->malloced = true;

-- 

1.8.3.1