On 2015-01-28 13:38:51 -0500, Tom Lane wrote: > Andres Freund <and...@2ndquadrant.com> writes: > >> I personally still think that a comment above sbufdesc's definition > >> would be sufficient for now. But whatever. I'll enforce 64byte padding > >> on 64bit platforms, and do nothing on 32bit platforms. > > > Patch doing that attached. > > Surely the sizeof() in BufferShmemSize needs to be > sizeof(BufferDescPadded) now?
Good catch. It'd surely fail nastily later, once somebody actually made the size change away from 64 bytes. > Also, the macro is unnecessarily unsafe for use in #if tests; why not > something like Out of curiosity: What's the danger you're seing? I'm perfectly fine with using SIZEOF_VOID_P, I actually looked for a macro like it and didn't find anything. > #define BUFFERDESC_PADDED_SIZE (SIZEOF_VOID_P == 8 ? 64 : 32) Hm, did you intentionally put a 32in there or was that just the logical continuation of 64? Because there's no way it'll ever fit into 32 bytes in the near future. That's why I had put the sizeof(BufferDesc) there. We could just make it 1 as well, to indicate that we don't want any padding... > Otherwise it looks reasonably sane to me, just in a quick once-over; > I didn't test. I tested it on both 32/64 bit linux and it indeed fixes the issue of changing performance due to max_connections+-1. Greetings, Andres Freund -- Andres Freund http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers