| From: | David Rowley <dgrowleyml(at)gmail(dot)com> |
|---|---|
| To: | Andres Freund <andres(at)anarazel(dot)de> |
| Cc: | PostgreSQL Development <pgsql-hackers(at)postgresql(dot)org>, Robert Haas <robertmhaas(at)gmail(dot)com>, Michael Paquier <michael(dot)paquier(at)gmail(dot)com>, Tomas Vondra <tv(at)fuzzy(dot)cz> |
| Subject: | Re: Avoid stack frame setup in performance critical routines using tail calls |
| Date: | 2021-07-20 07:37:46 |
| Message-ID: | CAApHDvpmhKQTcbAT3ryr+_b8v9B53C1AXkV=EeQeUJ+mOQCH9Q@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Tue, 20 Jul 2021 at 19:04, Andres Freund <andres(at)anarazel(dot)de> wrote:
> > * AllocateSetAlloc.txt
> > * palloc.txt
> > * percent.txt
>
> Huh, that's interesting. You have some control flow enforcement stuff turned on (the endbr64). And it looks like it has a non zero cost (or maybe it's just skid). Did you enable that intentionally? If not, what compiler/version/distro is it? I think at least on GCC that's -fcf-protection=...
It's ubuntu 21.04 with gcc 10.3 (specifically gcc version 10.3.0
(Ubuntu 10.3.0-1ubuntu1)
I've attached the same results from compiling with clang 12
(12.0.0-3ubuntu1~21.04.1)
David
| Attachment | Content-Type | Size |
|---|---|---|
| AllocSetAlloc_clang.txt | text/plain | 4.5 KB |
| palloc_clang.txt | text/plain | 1.3 KB |
| percent_clang.txt | text/plain | 642 bytes |
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