On 2014-09-19 13:58:17 -0400, Robert Haas wrote: > On Wed, Sep 17, 2014 at 7:45 AM, Andres Freund <and...@2ndquadrant.com> wrote: > > I just tried this on my normal x86 workstation. I applied your lwlock > > patch and ontop I removed most volatiles (there's a couple still > > required) from xlog.c. Works for 100 seconds. Then I reverted the above > > commits. Breaks within seconds: > > master: > > LOG: request to flush past end of generated WAL; request 2/E5EC3DE0, > > currpos 2/E5EC1E60 > > standby: > > LOG: record with incorrect prev-link 4/684C3108 at 4/684C3108 > > and similar. > > > > So at least for x86 the compiler barriers are obviously required and > > seemingly working. > > Oh, that's great. In that case I think I should go ahead and apply > that patch in the hopes of turning up any systems where the barriers > aren't working properly yet.
Agreed. > Although it would be nice to know whether it breaks with *only* the lwlock.c > patch. It didn't, at least not visibly within the 1000s I let pgbench run. > > I've attached the very quickly written xlog.c de-volatizing patch. > > I don't have time to go through this in detail, but I don't object to > you applying it if you're confident you've done it carefully enough. It's definitely not yet carefully enough checked. I wanted to get it break fast and only made one pass through the file. But I think it should be easy enough to get it into shape for that. Greetings, Andres Freund -- Andres Freund http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers