On Tue 20-11-12 09:42:42, metin d wrote: > I have two PostgreSQL databases named data-1 and data-2 that sit on the > same machine. Both databases keep 40 GB of data, and the total memory > available on the machine is 68GB. > > I started data-1 and data-2, and ran several queries to go over all their > data. Then, I shut down data-1 and kept issuing queries against data-2. > For some reason, the OS still holds on to large parts of data-1's pages > in its page cache, and reserves about 35 GB of RAM to data-2's files. As > a result, my queries on data-2 keep hitting disk. > > I'm checking page cache usage with fincore. When I run a table scan query > against data-2, I see that data-2's pages get evicted and put back into > the cache in a round-robin manner. Nothing happens to data-1's pages, > although they haven't been touched for days. > > Does anybody know why data-1's pages aren't evicted from the page cache? > I'm open to all kind of suggestions you think it might relate to problem. Curious. Added linux-mm list to CC to catch more attention. If you run echo 1 >/proc/sys/vm/drop_caches does it evict data-1 pages from memory? > This is an EC2 m2.4xlarge instance on Amazon with 68 GB of RAM and no > swap space. The kernel version is: > > $ uname -r > 3.2.28-45.62.amzn1.x86_64 > Edit: > > and it seems that I use one NUMA instance, if you think that it can a problem. > > $ numactl --hardware > available: 1 nodes (0) > node 0 cpus: 0 1 2 3 4 5 6 7 > node 0 size: 70007 MB > node 0 free: 360 MB > node distances: > node 0 > 0: 10 Honza -- Jan Kara <jack@xxxxxxx> SUSE Labs, CR -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>