I'm trying to overcommit storage space on one our hypervisors (and reclaim space if possible after memory peak times) and it seems like kernel in Fedora 33 isn't doing automatic discard on swap partitions? The swap is enabled by:
$ swapon --discard /dev/sda The guest (on RHEL 8 HV host) is started with virtio-scsi controller to propagate the trim requests to the host storage, the volumes I tried were both of raw and qcow2 format. The 'fstrim -av' isn't propagated to SWAP mount points (expected probably). The only thing that helps to shrink the host volume allocated for guest swap is 'swapoff -a && swapon --discard /dev/sda' (but I assume TRIM is sent to the driver in this case, and that the problem isn't in the host libvirt setup). But otherwise, freeing the guest memory manually, minimizing the swap usage, etc. (experiments with tmpfs) doesn't result in freeing the allocated storage blocks on host. Am I doing something wrong, is this expected or is this a bug? FTR, I tested "kernel-core-5.10.11-200.fc33.x86_64" and "kernel-core-5.10.12-200.fc33.x86_64" but this is not a regression -- I'm experimenting with TRIM in this setup for the first time. Dmesg output seems to indicate page cluster trim is enabled (c symbol): [ 3936.914260] Adding 33554428k swap on /dev/sda. Priority:-2 extents:1 across:33554428k DscFS Thanks, Pavel _______________________________________________ devel mailing list -- devel@lists.fedoraproject.org To unsubscribe send an email to devel-le...@lists.fedoraproject.org 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/devel@lists.fedoraproject.org
