On Thu, Mar 24, 2022 at 6:36 AM Brad Bell <bradbell@xxxxxxxxxx> wrote: > > I am doing algorithmic differentiation with very large tapes and my jobs sometimes run out of memory. So the workload is producing a substantial amount of anonymous pages. It's kinda hard to tell what to do to optimize without a decent amount of knowledge about the workload's behavior. So you'd have to just change some things and see if the performance improves. I tentatively expect that you'd be better off disabling zram-generator, setting up a swap partition or file, and optionally enabling zswap (which is a different thing than zram). On the plus side, this frees up quite a lot of memory (roughly half), but on the negative side it might increase swap thrashing - it really depends on the workload. But zswap has the benefit of using Least Recently Used (LRU) to evict pages from the in-memory compressed cache pool to the conventional swap file. That way it's the stale pages going to disk and the active ones being compressed in memory. Also, for what it's worth, on Btrfs I use /var/swap/swapfile1 /var/swap/swapfile2 ... and so on. Where "varswap" is a subvolume located on the top-level of the file system (next to install time default subvolumes "root" and "home") and has chattr +C set on it. That way should I take snapshots of root (or even var in some custom configurations) I'm not snapshotting the swapfiles. Snapshotting the swap files ends up making them subject to COW again, and that's incompatible with using them as swapfiles. The entry in fstab looks like this: UUID=$uuid /var/swap btrfs noatime,subvol=varswap 0 0 man 5 btrfs has a SWAPFILE SUPPORT section that's fairly detailed steps. -- Chris Murphy _______________________________________________ users mailing list -- users@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to users-leave@xxxxxxxxxxxxxxxxxxxxxxx Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/users@xxxxxxxxxxxxxxxxxxxxxxx Do not reply to spam on the list, report it: https://pagure.io/fedora-infrastructure
