Re: [Qemu-devel] [Qemu-block] [PATCH COLO v3 10/14] util/hbitmap: Add an API to reset all set bits in hbitmap

[John Snow <jsnow@redhat.com>]

On 04/03/2015 07:05 AM, Paolo Bonzini wrote:
>
>
> On 03/04/2015 12:01, Wen Congyang wrote:
>> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
>> Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
>> Signed-off-by: Gonglei <arei.gonglei@huawei.com>
>> ---
>>   include/qemu/hbitmap.h |  8 ++++++++
>>   tests/test-hbitmap.c   | 39 +++++++++++++++++++++++++++++++++++++++
>>   util/hbitmap.c         | 16 ++++++++++++++++
>>   3 files changed, 63 insertions(+)
>>
>> diff --git a/include/qemu/hbitmap.h b/include/qemu/hbitmap.h
>> index 550d7ce..95a55e4 100644
>> --- a/include/qemu/hbitmap.h
>> +++ b/include/qemu/hbitmap.h
>> @@ -109,6 +109,14 @@ 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 8c902f2..1f0078a 100644
>> --- a/tests/test-hbitmap.c
>> +++ b/tests/test-hbitmap.c
>> @@ -11,6 +11,7 @@
>>
>>   #include <glib.h>
>>   #include <stdarg.h>
>> +#include <string.h>
>>   #include "qemu/hbitmap.h"
>>
>>   #define LOG_BITS_PER_LONG          (BITS_PER_LONG == 32 ? 5 : 6)
>> @@ -143,6 +144,23 @@ 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;
>> @@ -323,6 +341,26 @@ 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)
>>   {
>> @@ -394,6 +432,7 @@ 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);
>>       g_test_run();
>>
>> diff --git a/util/hbitmap.c b/util/hbitmap.c
>> index ab13971..acce93c 100644
>> --- a/util/hbitmap.c
>> +++ b/util/hbitmap.c
>> @@ -353,6 +353,22 @@ 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)
>> +{
>> +    uint64_t size = hb->size;
>> +    unsigned int i;
>> +
>> +    /* Same as hbitmap_alloc() except memset() */
>> +    for (i = HBITMAP_LEVELS; --i >= 1; ) {
>> +        size = MAX((size + BITS_PER_LONG - 1) >> BITS_PER_LEVEL, 1);
>> +        memset(hb->levels[i], 0, size * sizeof(unsigned long));
>> +    }
>> +

For what it's worth, I recently added in a hb->sizes[i] cache to store 
the size of each array so you don't have to recompute this all the time.

>> +    assert(size == 1);
>> +    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.  */
>>
>
> Acked-by: Paolo Bonzini <pbonzini@redhat.com>
>