Re: [tarantool-patches] [PATCH v3 1/7] memtx: introduce universal iterator_pool

[Konstantin Osipov <kostja@tarantool.org>]

* Vladimir Davydov <vdavydov.dev@gmail.com> [19/02/24 10:01]:
> On Fri, Feb 22, 2019 at 09:37:25PM +0300, Konstantin Osipov wrote:
> > * Kirill Shcherbatov <kshcherbatov@tarantool.org> [19/02/22 19:29]:
> > > Memtx uses separate mempools for iterators of different types.
> > > Due to the fact that there will be more iterators of different
> > > sizes in a series of upcoming changes, let's always allocate the
> > > iterator of the largest size.
> > 
> > If rtree iterator is the one which is largest, let's use a
> > separate pool for it. 
> > 
> > In general mempools are rather cheap. Each mempool takes a slab
> > for ~100 objects and uses no slabs if there are no objects (e.g.
> > if rtree index is not used, there is no mempool memory for it).
> 
> But I'd rather prefer to use the same mempool for all kinds of iterator
> objects to simplify the code. Take a look at how those mempools are
> initialized on demand. IMO it looks ugly. Do we really want to save
> those 500 of bytes that much to put up with that complexity?

Just like in the recent bps tree performance issue, you don't
pessimise the code since you never really know how it's going to
be used.


-- 
Konstantin Osipov, Moscow, Russia, +7 903 626 22 32
http://tarantool.io - www.twitter.com/kostja_osipov