diff mbox

[v5,02/10] HBitmap: Introduce "meta" bitmap to track bit changes

Message ID 1464928382-9650-3-git-send-email-famz@redhat.com (mailing list archive)
State New, archived
Headers show

Commit Message

Fam Zheng June 3, 2016, 4:32 a.m. UTC 
Upon each bit toggle, the corresponding bit in the meta bitmap will be
set.

Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
---
 block/dirty-bitmap.c   |  2 +-
 include/qemu/hbitmap.h | 17 +++++++++++++
 util/hbitmap.c         | 69 +++++++++++++++++++++++++++++++++++++++-----------
 3 files changed, 72 insertions(+), 16 deletions(-)

Comments

Max Reitz June 22, 2016, 3:22 p.m. UTC | #1 
On 03.06.2016 06:32, Fam Zheng wrote:
> Upon each bit toggle, the corresponding bit in the meta bitmap will be
> set.
> 
> Signed-off-by: Fam Zheng <famz@redhat.com>
> Reviewed-by: John Snow <jsnow@redhat.com>
> ---
>  block/dirty-bitmap.c   |  2 +-
>  include/qemu/hbitmap.h | 17 +++++++++++++
>  util/hbitmap.c         | 69 +++++++++++++++++++++++++++++++++++++++-----------
>  3 files changed, 72 insertions(+), 16 deletions(-)
> 
> diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
> index ec073ee..628b77c 100644
> --- a/block/dirty-bitmap.c
> +++ b/block/dirty-bitmap.c
> @@ -231,7 +231,7 @@ static void bdrv_do_release_matching_dirty_bitmap(BlockDriverState *bs,
>      BdrvDirtyBitmap *bm, *next;
>      QLIST_FOREACH_SAFE(bm, &bs->dirty_bitmaps, list, next) {
>          if ((!bitmap || bm == bitmap) && (!only_named || bm->name)) {
> -            assert(!bitmap->active_iterators);
> +            assert(!bm->active_iterators);

Same comment as for v4, this should be squashed into the previous patch.

Max
John Snow July 13, 2016, 5:39 p.m. UTC | #2 
On 06/22/2016 11:22 AM, Max Reitz wrote:
> On 03.06.2016 06:32, Fam Zheng wrote:
>> Upon each bit toggle, the corresponding bit in the meta bitmap will be
>> set.
>>
>> Signed-off-by: Fam Zheng <famz@redhat.com>
>> Reviewed-by: John Snow <jsnow@redhat.com>
>> ---
>>  block/dirty-bitmap.c   |  2 +-
>>  include/qemu/hbitmap.h | 17 +++++++++++++
>>  util/hbitmap.c         | 69 +++++++++++++++++++++++++++++++++++++++-----------
>>  3 files changed, 72 insertions(+), 16 deletions(-)
>>
>> diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
>> index ec073ee..628b77c 100644
>> --- a/block/dirty-bitmap.c
>> +++ b/block/dirty-bitmap.c
>> @@ -231,7 +231,7 @@ static void bdrv_do_release_matching_dirty_bitmap(BlockDriverState *bs,
>>      BdrvDirtyBitmap *bm, *next;
>>      QLIST_FOREACH_SAFE(bm, &bs->dirty_bitmaps, list, next) {
>>          if ((!bitmap || bm == bitmap) && (!only_named || bm->name)) {
>> -            assert(!bitmap->active_iterators);
>> +            assert(!bm->active_iterators);
> 
> Same comment as for v4, this should be squashed into the previous patch.
> 
> Max
> 

Ah, replied too soon on #1. Thanks :)
diff mbox

Patch

diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
index ec073ee..628b77c 100644
--- a/block/dirty-bitmap.c
+++ b/block/dirty-bitmap.c
@@ -231,7 +231,7 @@  static void bdrv_do_release_matching_dirty_bitmap(BlockDriverState *bs,
     BdrvDirtyBitmap *bm, *next;
     QLIST_FOREACH_SAFE(bm, &bs->dirty_bitmaps, list, next) {
         if ((!bitmap || bm == bitmap) && (!only_named || bm->name)) {
-            assert(!bitmap->active_iterators);
+            assert(!bm->active_iterators);
             assert(!bdrv_dirty_bitmap_frozen(bm));
             QLIST_REMOVE(bm, list);
             hbitmap_free(bm->bitmap);
diff --git a/include/qemu/hbitmap.h b/include/qemu/hbitmap.h
index e29188c..f8ed058 100644
--- a/include/qemu/hbitmap.h
+++ b/include/qemu/hbitmap.h
@@ -178,6 +178,23 @@  void hbitmap_iter_init(HBitmapIter *hbi, const HBitmap *hb, uint64_t first);
  */
 unsigned long hbitmap_iter_skip_words(HBitmapIter *hbi);
 
+/* hbitmap_create_meta:
+ * Create a "meta" hbitmap to track dirtiness of the bits in this HBitmap.
+ * The caller owns the created bitmap and must call hbitmap_free_meta(hb) to
+ * free it.
+ *
+ * @hb: The HBitmap to operate on.
+ * @chunk_size: How many bits in @hb does one bit in the meta track.
+ */
+HBitmap *hbitmap_create_meta(HBitmap *hb, int chunk_size);
+
+/* hbitmap_free_meta:
+ * Free the meta bitmap of @hb.
+ *
+ * @hb: The HBitmap whose meta bitmap should be freed.
+ */
+void hbitmap_free_meta(HBitmap *hb);
+
 /**
  * hbitmap_iter_next:
  * @hbi: HBitmapIter to operate on.
diff --git a/util/hbitmap.c b/util/hbitmap.c
index b22b87d..13c0df5 100644
--- a/util/hbitmap.c
+++ b/util/hbitmap.c
@@ -79,6 +79,9 @@  struct HBitmap {
      */
     int granularity;
 
+    /* A meta dirty bitmap to track the dirtiness of bits in this HBitmap. */
+    HBitmap *meta;
+
     /* A number of progressively less coarse bitmaps (i.e. level 0 is the
      * coarsest).  Each bit in level N represents a word in level N+1 that
      * has a set bit, except the last level where each bit represents the
@@ -210,25 +213,27 @@  static uint64_t hb_count_between(HBitmap *hb, uint64_t start, uint64_t last)
 }
 
 /* Setting starts at the last layer and propagates up if an element
- * changes from zero to non-zero.
+ * changes.
  */
 static inline bool hb_set_elem(unsigned long *elem, uint64_t start, uint64_t last)
 {
     unsigned long mask;
-    bool changed;
+    unsigned long old;
 
     assert((last >> BITS_PER_LEVEL) == (start >> BITS_PER_LEVEL));
     assert(start <= last);
 
     mask = 2UL << (last & (BITS_PER_LONG - 1));
     mask -= 1UL << (start & (BITS_PER_LONG - 1));
-    changed = (*elem == 0);
+    old = *elem;
     *elem |= mask;
-    return changed;
+    return old != *elem;
 }
 
-/* The recursive workhorse (the depth is limited to HBITMAP_LEVELS)... */
-static void hb_set_between(HBitmap *hb, int level, uint64_t start, uint64_t last)
+/* The recursive workhorse (the depth is limited to HBITMAP_LEVELS)...
+ * Returns true if at least one bit is changed. */
+static bool hb_set_between(HBitmap *hb, int level, uint64_t start,
+                           uint64_t last)
 {
     size_t pos = start >> BITS_PER_LEVEL;
     size_t lastpos = last >> BITS_PER_LEVEL;
@@ -257,22 +262,27 @@  static void hb_set_between(HBitmap *hb, int level, uint64_t start, uint64_t last
     if (level > 0 && changed) {
         hb_set_between(hb, level - 1, pos, lastpos);
     }
+    return changed;
 }
 
 void hbitmap_set(HBitmap *hb, uint64_t start, uint64_t count)
 {
     /* Compute range in the last layer.  */
+    uint64_t first, n;
     uint64_t last = start + count - 1;
 
     trace_hbitmap_set(hb, start, count,
                       start >> hb->granularity, last >> hb->granularity);
 
-    start >>= hb->granularity;
+    first = start >> hb->granularity;
     last >>= hb->granularity;
-    count = last - start + 1;
+    n = last - first + 1;
 
-    hb->count += count - hb_count_between(hb, start, last);
-    hb_set_between(hb, HBITMAP_LEVELS - 1, start, last);
+    hb->count += n - hb_count_between(hb, first, last);
+    if (hb_set_between(hb, HBITMAP_LEVELS - 1, first, last) &&
+        hb->meta) {
+        hbitmap_set(hb->meta, start, count);
+    }
 }
 
 /* Resetting works the other way round: propagate up if the new
@@ -293,8 +303,10 @@  static inline bool hb_reset_elem(unsigned long *elem, uint64_t start, uint64_t l
     return blanked;
 }
 
-/* The recursive workhorse (the depth is limited to HBITMAP_LEVELS)... */
-static void hb_reset_between(HBitmap *hb, int level, uint64_t start, uint64_t last)
+/* The recursive workhorse (the depth is limited to HBITMAP_LEVELS)...
+ * Returns true if at least one bit is changed. */
+static bool hb_reset_between(HBitmap *hb, int level, uint64_t start,
+                             uint64_t last)
 {
     size_t pos = start >> BITS_PER_LEVEL;
     size_t lastpos = last >> BITS_PER_LEVEL;
@@ -337,21 +349,28 @@  static void hb_reset_between(HBitmap *hb, int level, uint64_t start, uint64_t la
     if (level > 0 && changed) {
         hb_reset_between(hb, level - 1, pos, lastpos);
     }
+
+    return changed;
+
 }
 
 void hbitmap_reset(HBitmap *hb, uint64_t start, uint64_t count)
 {
     /* Compute range in the last layer.  */
+    uint64_t first;
     uint64_t last = start + count - 1;
 
     trace_hbitmap_reset(hb, start, count,
                         start >> hb->granularity, last >> hb->granularity);
 
-    start >>= hb->granularity;
+    first = start >> hb->granularity;
     last >>= hb->granularity;
 
-    hb->count -= hb_count_between(hb, start, last);
-    hb_reset_between(hb, HBITMAP_LEVELS - 1, start, last);
+    hb->count -= hb_count_between(hb, first, last);
+    if (hb_reset_between(hb, HBITMAP_LEVELS - 1, first, last) &&
+        hb->meta) {
+        hbitmap_set(hb->meta, start, count);
+    }
 }
 
 void hbitmap_reset_all(HBitmap *hb)
@@ -379,6 +398,7 @@  bool hbitmap_get(const HBitmap *hb, uint64_t item)
 void hbitmap_free(HBitmap *hb)
 {
     unsigned i;
+    assert(!hb->meta);
     for (i = HBITMAP_LEVELS; i-- > 0; ) {
         g_free(hb->levels[i]);
     }
@@ -456,6 +476,9 @@  void hbitmap_truncate(HBitmap *hb, uint64_t size)
                    (size - old) * sizeof(*hb->levels[i]));
         }
     }
+    if (hb->meta) {
+        hbitmap_truncate(hb->meta, hb->size << hb->granularity);
+    }
 }
 
 
@@ -491,3 +514,19 @@  bool hbitmap_merge(HBitmap *a, const HBitmap *b)
 
     return true;
 }
+
+HBitmap *hbitmap_create_meta(HBitmap *hb, int chunk_size)
+{
+    assert(!(chunk_size & (chunk_size - 1)));
+    assert(!hb->meta);
+    hb->meta = hbitmap_alloc(hb->size << hb->granularity,
+                             hb->granularity + ctz32(chunk_size));
+    return hb->meta;
+}
+
+void hbitmap_free_meta(HBitmap *hb)
+{
+    assert(hb->meta);
+    hbitmap_free(hb->meta);
+    hb->meta = NULL;
+}