On Wed, Jun 26, 2013 at 03:53:21PM +0200, folkert wrote: > I noticed that on my 3 VMs running server, that there are 10-20 threads > doing i/o. As the VMs are running on HDDs and not SSDs I think that is > counterproductive: won't these threads make the HDDs seek back and forth > constantly?
The worker threads are doing preadv()/pwritev()/fdatasync(). It's up to the host kernel to schedule that I/O efficiently. Exposing more I/O to the host gives it a chance to merge or reorder I/O for optimal performance, so it's a good thing. On the other hand, if QEMU only did 1 or 2 I/O requests at a time then the host kernel could do nothing to improve the I/O pattern and the disks would indeed "seek back and forth constantly". Stefan -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
