Re: Streaming I/O, vectored I/O (WIP)

On 29/03/2024 09:01, Thomas Munro wrote:
> On Fri, Mar 29, 2024 at 9:45 AM Heikki Linnakangas <hlinnaka(at)iki(dot)fi> wrote:
>> master (213c959a29): 8.0 s
>> streaming-api v13: 9.5 s
>
> Hmm, that's not great, and I think I know one factor that has
> confounded my investigation and the conflicting reports I have
> received from a couple of people: some are using meson, which is
> defaulting to -O3 by default, and others are using make which gives
> you -O2 by default, but at -O2, GCC doesn't inline that
> StartReadBuffer specialisation that is used in the "fast path", and
> possibly more. Some of that gap is closed by using
> pg_attribute_inline_always. Clang fails to inline at any level. So I
> should probably use the "always" macro there because that is the
> intention. Still processing the rest of your email...

Ah yeah, I also noticed that the inlining didn't happen with some
compilers and flags. I use a mix of gcc and clang and meson and autoconf
in my local environment.

The above micro-benchmarks were with meson and gcc -O3. GCC version:

$ gcc --version
gcc (Debian 12.2.0-14) 12.2.0
Copyright (C) 2022 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

--
Heikki Linnakangas
Neon (https://neon.tech)