On Thursday, June 28, 2012 07:19:46 PM Magnus Hagander wrote: > On Thu, Jun 28, 2012 at 7:15 PM, Robert Haas <robertmh...@gmail.com> wrote: > > On Thu, Jun 28, 2012 at 12:13 PM, Thom Brown <t...@linux.com> wrote: > >> On 64-bit Linux, if I allocate more shared buffers than the system is > >> capable of reserving, it doesn't start. This is expected, but there's > >> no error logged anywhere (actually, nothing logged at all), and the > >> postmaster.pid file is left behind after this failure. > > > > Fixed. > > > > However, I discovered something unpleasant. With the new code, on > > MacOS X, if you set shared_buffers to say 3200GB, the server happily > > starts up. Or at least the shared memory allocation goes through just > > fine. The postmaster then sits there apparently forever without > > emitting any log messages, which I eventually discovered was because > > it's busy initializing a billion or so spinlocks. > > > > I'm pretty sure that this machine does not have >3TB of virtual > > memory, even counting swap. So that means that MacOS X has absolutely > > no common sense whatsoever as far as anonymous shared memory > > allocations go. Not sure exactly what to do about that. Linux is > > more sensible, at least on the system I tested, and fails cleanly. > > What happens if you mlock() it into memory - does that fail quickly? > Is that not something we might want to do *anyway*? You normally can only mlock() mminor amounts of memory without changing settings. Requiring to change that setting (aside that mlocking would be a bad idea imo) would run contrary to the point of the patch, wouldn't it? ;)
Andres -- 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
