It is interesting that for me the number of extents before and after bcache are essentially the same. The lesson here for me there is that the fragmentation of a btrfs nodatacow file is not mitigated by bcache. There seems to be nothing I can do to prevent that fragmentation, and may in fact be expected behavior. I cannot prove that adding the SSD bcache front-end improved performance of the guest VM, though subjectively it seems to have had a positive effect. There is something systemically pathological with the VM in question, but that's a different mailing list. :) -rb On Tue, Sep 2, 2014 at 11:26 PM, Chris Murphy <lists@xxxxxxxxxxxxxxxxx> wrote: > > On Sep 3, 2014, at 12:01 AM, Chris Murphy <lists@xxxxxxxxxxxxxxxxx> wrote: > >> I created two pools, one xfs one btrfs, default formatting and mount options. I then created a qcow2 file on each using virt-manager, also using default options. And default caching (whatever that is, I think it's writethrough but don't hold me to it). > > On the btrfs qcow2, xattr C was set. > > > Chris Murphy-- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
