Re: [Qemu-devel] [PATCH] util/hbitmap: Add an API to reset all set bits in hbitmap

[John Snow]

On 05/07/2015 09:12 PM, Wen Congyang wrote:
> The function bdrv_clear_dirty_bitmap() is updated to use
> faster hbitmap_reset_all() call.
> 
> Signed-off-by: Wen Congyang <address@hidden>
> Signed-off-by: zhanghailiang <address@hidden>
> Signed-off-by: Gonglei <address@hidden>
> Acked-by: Paolo Bonzini <address@hidden>
> ---
>  block.c                |  2 +-
>  include/qemu/hbitmap.h |  8 ++++++++
>  tests/test-hbitmap.c   | 38 ++++++++++++++++++++++++++++++++++++++
>  util/hbitmap.c         | 13 +++++++++++++
>  4 files changed, 60 insertions(+), 1 deletion(-)
> 
> diff --git a/block.c b/block.c
> index 7904098..49d472f 100644
> --- a/block.c
> +++ b/block.c
> @@ -3309,7 +3309,7 @@ void bdrv_reset_dirty_bitmap(BdrvDirtyBitmap *bitmap,
>  void bdrv_clear_dirty_bitmap(BdrvDirtyBitmap *bitmap)
>  {
>      assert(bdrv_dirty_bitmap_enabled(bitmap));
> -    hbitmap_reset(bitmap->bitmap, 0, bitmap->size);
> +    hbitmap_reset_all(bitmap->bitmap);
>  }
>  
>  void bdrv_set_dirty(BlockDriverState *bs, int64_t cur_sector,
> diff --git a/include/qemu/hbitmap.h b/include/qemu/hbitmap.h
> index f0a85f8..bb94a00 100644
> --- a/include/qemu/hbitmap.h
> +++ b/include/qemu/hbitmap.h
> @@ -132,6 +132,14 @@ void hbitmap_set(HBitmap *hb, uint64_t start, uint64_t 
> count);
>  void hbitmap_reset(HBitmap *hb, uint64_t start, uint64_t count);
>  
>  /**
> + * hbitmap_reset_all:
> + * @hb: HBitmap to operate on.
> + *
> + * Reset all bits in an HBitmap.
> + */
> +void hbitmap_reset_all(HBitmap *hb);
> +
> +/**
>   * hbitmap_get:
>   * @hb: HBitmap to operate on.
>   * @item: Bit to query (0-based).
> diff --git a/tests/test-hbitmap.c b/tests/test-hbitmap.c
> index 9f41b5f..161eeb4 100644
> --- a/tests/test-hbitmap.c
> +++ b/tests/test-hbitmap.c
> @@ -184,6 +184,23 @@ static void hbitmap_test_reset(TestHBitmapData *data,
>      }
>  }
>  
> +static void hbitmap_test_reset_all(TestHBitmapData *data)
> +{
> +    size_t n;
> +
> +    hbitmap_reset_all(data->hb);
> +
> +    n = (data->size + BITS_PER_LONG - 1) / BITS_PER_LONG;
> +    if (n == 0) {
> +        n = 1;
> +    }
> +    memset(data->bits, 0, n * sizeof(unsigned long));
> +
> +    if (data->granularity == 0) {
> +        hbitmap_test_check(data, 0);
> +    }
> +}
> +
>  static void hbitmap_test_check_get(TestHBitmapData *data)
>  {
>      uint64_t count = 0;
> @@ -364,6 +381,26 @@ static void test_hbitmap_reset(TestHBitmapData *data,
>      hbitmap_test_set(data, L3 / 2, L3);
>  }
>  
> +static void test_hbitmap_reset_all(TestHBitmapData *data,
> +                                   const void *unused)
> +{
> +    hbitmap_test_init(data, L3 * 2, 0);
> +    hbitmap_test_set(data, L1 - 1, L1 + 2);
> +    hbitmap_test_reset_all(data);
> +    hbitmap_test_set(data, 0, L1 * 3);
> +    hbitmap_test_reset_all(data);
> +    hbitmap_test_set(data, L2, L1);
> +    hbitmap_test_reset_all(data);
> +    hbitmap_test_set(data, L2, L3 - L2 + 1);
> +    hbitmap_test_reset_all(data);
> +    hbitmap_test_set(data, L3 - 1, 3);
> +    hbitmap_test_reset_all(data);
> +    hbitmap_test_set(data, 0, L3 * 2);
> +    hbitmap_test_reset_all(data);
> +    hbitmap_test_set(data, L3 / 2, L3);
> +    hbitmap_test_reset_all(data);
> +}
> +
>  static void test_hbitmap_granularity(TestHBitmapData *data,
>                                       const void *unused)
>  {
> @@ -627,6 +664,7 @@ int main(int argc, char **argv)
>      hbitmap_test_add("/hbitmap/set/overlap", test_hbitmap_set_overlap);
>      hbitmap_test_add("/hbitmap/reset/empty", test_hbitmap_reset_empty);
>      hbitmap_test_add("/hbitmap/reset/general", test_hbitmap_reset);
> +    hbitmap_test_add("/hbitmap/reset/all", test_hbitmap_reset_all);
>      hbitmap_test_add("/hbitmap/granularity", test_hbitmap_granularity);
>  
>      hbitmap_test_add("/hbitmap/truncate/nop", test_hbitmap_truncate_nop);
> diff --git a/util/hbitmap.c b/util/hbitmap.c
> index a10c7ae..25d3cdb 100644
> --- a/util/hbitmap.c
> +++ b/util/hbitmap.c
> @@ -356,6 +356,19 @@ void hbitmap_reset(HBitmap *hb, uint64_t start, uint64_t 
> count)
>      hb_reset_between(hb, HBITMAP_LEVELS - 1, start, last);
>  }
>  
> +void hbitmap_reset_all(HBitmap *hb)
> +{
> +    unsigned int i;
> +
> +    /* Same as hbitmap_alloc() except memset() */
> +    for (i = HBITMAP_LEVELS; --i >= 1; ) {
> +        memset(hb->levels[i], 0, hb->sizes[i] * sizeof(unsigned long));
> +    }
> +
> +    hb->levels[0][0] = 1UL << (BITS_PER_LONG - 1);
> +    hb->count = 0;
> +}
> +
>  bool hbitmap_get(const HBitmap *hb, uint64_t item)
>  {
>      /* Compute position and bit in the last layer.  */
> 

Thanks!

Reviewed-by: John Snow <address@hidden>