On 1/13/14, 4:47 PM, Jan Kara wrote:
Note to postgres guys: I think you should have a look at the proposed 'vrange' system call. The latest posting is here: http://www.spinics.net/lists/linux-mm/msg67328.html. It contains a rather detailed description of the feature. And if the feature looks good to you, you can add your 'me to' plus if anyone would be willing to try that out with postgress that would be most welcome (although I understand you might not want to burn your time on experimental kernel feature).
I don't think that would help us with buffers unless we switched to MMAP (which is a huge change), but this part is interesting: "* Opportunistic freeing of memory that may be quickly reused. Minchan has done a malloc implementation where free() marks the pages as volatile, allowing the kernel to reclaim under pressure. This avoids the unmapping and remapping of anonymous pages on free/malloc." Postgres has it's own memory management on top of malloc that gives us memory contexts; some of those contexts get destroyed frequently. Allowing the kernel to reclaim that free'd memory in the background might be a performance win for us. -- Jim C. Nasby, Data Architect j...@nasby.net 512.569.9461 (cell) http://jim.nasby.net -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
