| From: | Andres Freund <andres(at)2ndquadrant(dot)com> |
|---|---|
| To: | Jeff Davis <pgsql(at)j-davis(dot)com> |
| Cc: | PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, Ants Aasma <ants(at)cybertec(dot)at>, Florian Pflug <fgp(at)phlo(dot)org>, Simon Riggs <simon(at)2ndquadrant(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Greg Smith <greg(at)2ndquadrant(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Bruce Momjian <bruce(at)momjian(dot)us>, Heikki Linnakangas <hlinnakangas(at)vmware(dot)com> |
| Subject: | Re: Substituting Checksum Algorithm (was: Enabling Checksums) |
| Date: | 2013-04-23 08:47:38 |
| Message-ID: | 20130423084738.GA9063@awork2.anarazel.de |
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| Lists: | pgsql-hackers |
On 2013-04-23 00:17:28 -0700, Jeff Davis wrote:
> + # important optimization flags for checksum.c
> + ifeq ($(GCC),yes)
> + checksum.o: CFLAGS += -msse4.1 -funroll-loops -ftree-vectorize
> + endif
I am pretty sure we can't do those unconditionally:
- -funroll-loops and -ftree-vectorize weren't always part of gcc afair,
so we would need a configure check for those
- SSE4.1 looks like a total no-go, its not available everywhere. We
*can* add runtime detection of that with gcc fairly easily and
one-time if we wan't to go there (later?) using 'ifunc's, but that
needs a fair amount of infrastructure work.
- We can rely on SSE1/2 on amd64, but I think thats automatically
enabled there.
Greetings,
Andres Freund
--
Andres Freund http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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