On Thu, Jun 28, 2012 at 7:27 PM, Andres Freund <and...@2ndquadrant.com> wrote: > 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? ;)
It would. I wasn't aware of that limitation :) -- Magnus Hagander Me: http://www.hagander.net/ Work: http://www.redpill-linpro.com/ -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
