On Fri, May 30, 2014 at 03:54:49PM +0200, Heinz Mauelshagen wrote: > On 05/30/2014 03:46 PM, Richard W.M. Jones wrote: > >I have now set both read_promote_adjustment == > >write_promote_adjustment == 0 and used drop_caches between runs. > > Did you adjust "sequential_threshold 0" as well? > > dm-cache tries to avoid promoting large sequential files to the cache, > because spindles have good bandwidth. > > This is again because of the hot spot caching nature of dm-cache. Setting this had no effect. I starting to wonder if my settings are having any effect at all. Here are the device-mapper tables: $ sudo dmsetup table vg_guests-lv_cache_cdata: 0 419430400 linear 8:33 2099200 vg_guests-lv_cache_cmeta: 0 2097152 linear 8:33 2048 vg_guests-home: 0 209715200 linear 9:127 2048 vg_guests-libvirt--images: 0 1677721600 cache 253:1 253:0 253:2 128 0 default 0 vg_guests-libvirt--images_corig: 0 1677721600 linear 9:127 2055211008 And here is the command I used to set sequential_threshold to 0 (there was no error and no other output): $ sudo dmsetup message vg_guests-libvirt--images 0 sequential_threshold 0 Is there a way to print the current settings? Could writethrough be enabled? (I'm supposed to be using writeback). How do I find out? Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-top is 'top' for virtual machines. Tiny program with many powerful monitoring features, net stats, disk stats, logging, etc. http://people.redhat.com/~rjones/virt-top _______________________________________________ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
