On 07/22/2016 05:57 PM, Max Reitz wrote: > 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 >
Haha, alright. I will ACTUALLY sit down and make this nice tonight. I'll have to turn off autopilot for a few bleeding moments. --js >> + >> + /* 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; >> +} >