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

[John Snow]

On 04/03/2015 07:05 AM, Paolo Bonzini wrote:
> On 03/04/2015 12:01, Wen Congyang wrote:
> > Signed-off-by: Wen Congyang <address@hidden>
> > Signed-off-by: zhanghailiang <address@hidden>
> > Signed-off-by: Gonglei <address@hidden>
> > ---
> >   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 <address@hidden>