Have you ruled out the usual suspects - lack of memory and physically bad hard disk?
--- Supratim Sanyal, W1XMT 39.19151 N, 77.23432 W QCOCAL::SANYAL via HECnet > On Aug 2, 2020, at 4:31 AM, Z <danz...@gmail.com> wrote: > > First, hello to the list. and second on to why i am here. > > Not sure if this is normal behavior or just my setup . > > But i am getting constant disk thrashing for about a second > about every 3 seconds for 10 to 20 times after almost > any operation in any guest , be it linux winxp win2k bsd... > And with 5 not so quiet 2.5 inch 500 gig dell drives and workstation > close by , it gets pretty annoying, as i do not mind normal > access to disk but the periodic nature kind of bugs me. > > Setup is devuan(debian without systemd) stable and tried testing with > same results. > Running ZFS in raidz 5 drives (tried both sync on and off) with a > dataset that contains > kvm raw and qcow2 images. > > Tried every cache mode for virtual disks , thought it could be disk or > stat pooling > which is set to 3 sec by default, but changing period and turning all > pooling off does > not change the constant paging out to disk . Watching ntop and iotop > its qemu-system-x86-64 > that is doing the write-(flushing), but why do 10 or 20 flushes after > a simple disk access > when one could suffice ? and that means its constantly doing this > disk thrashing > while using any guest , without even asking for any real disk access > like moving > files etc, any simple read to load something small in guest triggers this. > > Went though all the config files for qemu and libvirtd , and hours in google > but cannot find anything relevant . > > thanx in advance > > dan >
