On 1/31/16 7:38 PM, Kouhei Kaigai wrote: > I'm under investigation of SSD-to-GPU direct feature on top of > the custom-scan interface. It intends to load a bunch of data > blocks on NVMe-SSD to GPU RAM using P2P DMA, prior to the data > loading onto CPU/RAM, to preprocess the data to be filtered out. > It only makes sense if the target blocks are not loaded to the > CPU/RAM yet, because SSD device is essentially slower than RAM. > So, I like to have a reliable way to check the latest status of > the shared buffer, to kwon whether a particular block is already > loaded or not.
That completely ignores the OS cache though... wouldn't that be a major issue? To answer your direct question, I'm no expert, but I haven't seen any functions that do exactly what you want. You'd have to pull relevant bits from ReadBuffer_*. Or maybe a better method would just be to call BufTableLookup() without any locks and if you get a result > -1 just call the relevant ReadBuffer function. Sometimes you'll end up calling ReadBuffer even though the buffer isn't in shared buffers, but I would think that would be a rare occurrence. -- Jim Nasby, Data Architect, Blue Treble Consulting, Austin TX Experts in Analytics, Data Architecture and PostgreSQL Data in Trouble? Get it in Treble! http://BlueTreble.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
