From: Eric Wong <normalperson@...>
Date: 2015-12-03T22:51:08+00:00
Subject: [ruby-core:71819] Re: [Ruby trunk - Bug #11768] [Open] Add a polymorphic inline cache

tenderlove@ruby-lang.org wrote:
> I haven't run every benchmark that's checked in, but this patch speeds
> up the polymorphic call benchmark by about 20%.

Nice!

> The down side of this patch is that it increases memory usage because
> the size of the call cache struct gets larger, even if the call site
> is monomorphic.  I think we could make the code expand and contract,
> but I'm not sure if it's worthwhile.

Perhaps you can simplify the code so the existing monomorphic cache is
just: POLYMORPHIC_CACHE_SIZE == 1

By the way, how did you arrive at the value of 6?

Memory usage is a bigger problem of Ruby than speed to me;
so maybe a smaller value is a compromise.

> The other downside is that it will probably slow down calls if the
> global method state changes, but I don't think that is a situation we
> should optimize for.

Agreed.  Did you measure startup performance?