On 05.05.2015 15:18, Vasiliy Tolstov wrote: > As i see in some cases, for example in case of lvm storage pool > libvirt spawns libvirt_iohelper to upload or download data to volume. > But in case of big data contains zeroes this is wast bw of network. > May be we can use gzip or lz4 for compression stream? > How the best do this not breaking exiting software? > May be add new parameter to libvirt_iohelper with compression method > and compression level? In my cases of 20-160 Gb data and used only 4-5 > Gb this provide major benefit.... > Thanks! > The main benefit of using iohelper is that we have aligned reads from disks and thus can use O_DIRECT flag. So if anything, any compression must be put in between iohelper and the daemon which then resends data to clients. Unfortunately, we don't have a field in the API signature that can be used to select desired algorithm. We have @flags which could be used to enable compression. Which algorithm to use can be set in a config file (libvirtd.conf seems most suitable). Michal -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list