On 18.07.2016 22:57, John Snow wrote: > From: Fam Zheng <f...@redhat.com> > > The added group of operations enables tracking of the changed bits in > the dirty bitmap. > > Signed-off-by: Fam Zheng <f...@redhat.com> > Reviewed-by: Max Reitz <mre...@redhat.com> > Signed-off-by: John Snow <js...@redhat.com> > --- > block/dirty-bitmap.c | 52 > ++++++++++++++++++++++++++++++++++++++++++++ > include/block/dirty-bitmap.h | 9 ++++++++ > 2 files changed, 61 insertions(+)
[...] > +int bdrv_dirty_bitmap_get_meta(BlockDriverState *bs, > + BdrvDirtyBitmap *bitmap, int64_t sector, > + int nb_sectors) > +{ > + uint64_t i; > + int gran = hbitmap_granularity(bitmap->meta); /me is making a note first: If John says an optimization may be premature, it probably is. Did I say hbitmap_granularity()? I may have wanted to actually say "1 << hbitmap_granularity()". Sorry. :-/ /me is making a second note now: Look up how something works before proposing it, not after someone has actually followed your advice. Max > + > + /* To optimize: we can make hbitmap to internally check the range in a > + * coarse level, or at least do it word by word. */ > + for (i = sector; i < sector + nb_sectors; i += gran) { > + if (hbitmap_get(bitmap->meta, i)) { > + return true; > + } > + } > + return false; > +}
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