On Wed, Sep 07, 2016 at 05:01:56PM -0700, Alexei Starovoitov wrote:
> On 9/7/16 4:46 PM, Omar Sandoval wrote:
> > From: Omar Sandoval <osandov@xxxxxx>
> >
> > This is a generally useful data structure, so make it available to
> > anyone else who might want to use it. It's also a nice cleanup
> > separating the allocation logic from the rest of the tag handling logic.
> >
> > The code is behind a new Kconfig option, CONFIG_SCALE_BITMAP, which is
> > only selected by CONFIG_BLOCK for now.
> >
> > This should be a complete noop functionality-wise.
> >
> > Signed-off-by: Omar Sandoval <osandov@xxxxxx>
> > ---
> > MAINTAINERS | 1 +
> > block/Kconfig | 1 +
> > block/blk-mq-tag.c | 469 ++++++++++---------------------------------
> > block/blk-mq-tag.h | 37 +---
> > block/blk-mq.c | 113 +++--------
> > block/blk-mq.h | 9 -
> > include/linux/blk-mq.h | 9 +-
> > include/linux/scale_bitmap.h | 340 +++++++++++++++++++++++++++++++
> > lib/Kconfig | 3 +
> > lib/Makefile | 2 +
> > lib/scale_bitmap.c | 305 ++++++++++++++++++++++++++++
> ...
> > diff --git a/include/linux/scale_bitmap.h b/include/linux/scale_bitmap.h
> > new file mode 100644
> > index 0000000..63f712b
> > --- /dev/null
> > +++ b/include/linux/scale_bitmap.h
> > @@ -0,0 +1,340 @@
> > +/*
> > + * Fast and scalable bitmaps.
> ...
> > +/**
> > + * struct scale_bitmap_word - Word in a &struct scale_bitmap.
> > + */
> > +struct scale_bitmap_word {
> > +/**
> > + * struct scale_bitmap - Scalable bitmap.
> > + *
> > + * A &struct scale_bitmap is spread over multiple cachelines to avoid ping-pong.
> > + * This trades off higher memory usage for better scalability.
> > + */
> > +struct scale_bitmap {
>
> scale_bitmap sounds odd, since 'scale' is also a verb.
> We also have lib/rhashtable.c:
> * Resizable, Scalable, Concurrent Hash Table
> everything is 'scalable' nowadays.
Agreed, I'm not a huge fan of the name.
> May be resizable bitmap would be a better name?
> 'struct rbitmap'... lib/rbitmap.c ?
>
Hm, the resizing operation isn't very well thought-out right now, it's
there because it's okay for the way blk-mq uses it, but it's definitely
not the point of the data structure. It's more of a cache-friendly
bitmap, or a sparse bitmap. `struct sbitmap`? `struct cbitmap`?
--
Omar
--
To unsubscribe from this list: send the line "unsubscribe linux-block" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
