On Wed, Nov 21, 2018 at 4:37 AM REIX, Tony <tony.r...@atos.net> wrote: > YES ! Reading this file, your suggestion should work ! Thx ! > > I've rebuilt and run the basic tests. We'll relaunch our tests asap.
I would be surprised if that makes a difference: anonymous-mmap-then-fork and SysV shm are just two different ways to exchange mappings between processes, but I'd expect the virtual memory object itself to be basically the same, in terms of constraints that might affect page size at least. If you were talking about mmap backed by a file (which is what you get for temporary parallel query segments if you tell it to use dynamic_shared_memory_type = mmap), that might be a different matter, because then the block size of the file system backing it might come into the picture and limit the kernel's options. For example, that is why (with default settings) Parallel Hash can't use large pages on Linux (because Linux's POSIX shm_open() really just opens files on /dev/shm, which has a 4k block size), but can use them on FreeBSD (because its shm_open() isn't bound to page sizes, it can and sometimes decides to use large pages). -- Thomas Munro http://www.enterprisedb.com
