Re: Let's make PostgreSQL multi-threaded

On Wed, 7 Jun 2023 at 18:09, Andres Freund <andres(at)anarazel(dot)de> wrote:
> Having the same memory mapping between threads makes allows the
> hardware to share the TLB (on x86 via process context identifiers), which
> isn't realistically possible with different processes.

As a matter of historical interest Solaris actually did implement this
across different processes. It was called by the somewhat unfortunate
name "Intimate Shared Memory". I don't think Linux ever implemented
anything like it but I'm not sure.

I think this was not so much about cache hit rate but about just sheer
wasted memory in page mappings. So I guess hugepages more or less
target the same issues. But I find it interesting that they were
already running into issues like this 20 years ago -- presumably those
issues have only grown.

--
greg