| From: | Noah Misch <noah(at)leadboat(dot)com> |
|---|---|
| To: | Andres Freund <andres(at)anarazel(dot)de> |
| Cc: | Pg Hackers <pgsql-hackers(at)postgresql(dot)org>, Robert Haas <robertmhaas(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Peter Geoghegan <pg(at)heroku(dot)com>, Ants Aasma <ants(at)cybertec(dot)at> |
| Subject: | Re: xlc atomics |
| Date: | 2016-02-15 17:50:07 |
| Message-ID: | 20160215175007.GC347322@tornado.leadboat.com |
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| Lists: | pgsql-hackers |
On Mon, Feb 15, 2016 at 06:33:42PM +0100, Andres Freund wrote:
> On 2016-02-15 12:11:29 -0500, Noah Misch wrote:
> > These suggested OidGenLock wasn't doing its job. I've seen similar symptoms
> > around WALInsertLocks with "IBM XL C/C++ for Linux, V13.1.2 (5725-C73,
> > 5765-J08)" for ppc64le. The problem is generic-xlc.h
> > pg_atomic_compare_exchange_u32_impl() issuing __isync() before
> > __compare_and_swap(). __isync() shall follow __compare_and_swap(); see our
> > own s_lock.h, its references, and other projects' usage:
>
> Ugh. You're right! It's about not moving code before the stwcx...
>
> Do you want to add the new test (no objection, curious), or is that more
> for testing?
The patch's test would join PostgreSQL indefinitely.
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