Re: [Libguestfs] [PATCH nbdkit] file: Implement cache=none and fadvise=normal|random|sequential.

On Sat, Aug 08, 2020 at 02:14:22AM +0300, Nir Soffer wrote: Thanks for the explanation. Our use of file_flush (ie fdatasync) is less than ideal - we should probably use sync_file_range, which is what Linus suggested. However in this case it won't be a problem because we're only flushing the few pages we have just written. We control the file and there is no chance that the flush will cause an uncontrollable flood of data. The bigger issue to me: Sanlock should really be using cgroups or some mechanism to prioritize its block traffic over everything else. Any method to solve this where every single other process in the system is required to use direct I/O is IMO a ridiculous hack. What happens if some other process on the same machine happens to block the NFS server by writing lots? Perhaps the admin installs some proprietary backup software that we are unable to modify? Same thing would happen. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-df lists disk usage of guests without needing to install any software inside the virtual machine. Supports Linux and Windows. http://people.redhat.com/~rjones/virt-df/