Date: Wed, 17 Aug 2016 23:14:37 +0200 From: Rainer Duffner <rainer@ultra-secure.de> To: freebsd-stable <freebsd-stable@freebsd.org> Subject: I/O is very slow for FreeBSD 10.3 amd64 guest running on Citrix XenServer 6.5 Message-ID: <3FD6AFE8-BF63-4705-B826-FD8CD0A2F731@ultra-secure.de>
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Hi, I had to realize this week that my VMs on Citrix XenServer are very = slow, compared to Linux. I=E2=80=99m getting maybe 8 or 10 MB/s, wheres an Ubuntu 14 guest gets = 110+ MB/s (Megabyte). Independent of the filesystem, just wiping the disks with dc3dd. This went unnoticed, because not much I/O is done in these VMs. But = recently, a customer complained and I had to look into it. The VM is running stock 10.3-RELEASE-p6. The OS-type is set to FreeBSD 10 64 bit. Same thing happens with FreeBSD 11-RC1. This is what I get in 11-RC1 from sysctl: (freebsd11 </root>) 0 # sysctl -a |grep xen kern.vm_guest: xen device xenpci vfs.pfs.vncache.maxentries: 0 dev.xenbusb_back.0.%parent: xenstore0 dev.xenbusb_back.0.%pnpinfo: dev.xenbusb_back.0.%location: dev.xenbusb_back.0.%driver: xenbusb_back dev.xenbusb_back.0.%desc: Xen Backend Devices dev.xenbusb_back.%parent: dev.xn.0.xenstore_peer_path: /local/domain/0/backend/vif/245/0 dev.xn.0.xenbus_peer_domid: 0 dev.xn.0.xenbus_connection_state: Connected dev.xn.0.xenbus_dev_type: vif dev.xn.0.xenstore_path: device/vif/0 dev.xn.0.%parent: xenbusb_front0 dev.xbd.1.xenstore_peer_path: /local/domain/0/backend/vbd3/245/768 dev.xbd.1.xenbus_peer_domid: 0 dev.xbd.1.xenbus_connection_state: Connected dev.xbd.1.xenbus_dev_type: vbd dev.xbd.1.xenstore_path: device/vbd/768 dev.xbd.1.%parent: xenbusb_front0 dev.xbd.0.xenstore_peer_path: /local/domain/0/backend/vbd3/245/832 dev.xbd.0.xenbus_peer_domid: 0 dev.xbd.0.xenbus_connection_state: Connected dev.xbd.0.xenbus_dev_type: vbd dev.xbd.0.xenstore_path: device/vbd/832 dev.xbd.0.%parent: xenbusb_front0 dev.xenbusb_front.0.%parent: xenstore0 dev.xenbusb_front.0.%pnpinfo: dev.xenbusb_front.0.%location: dev.xenbusb_front.0.%driver: xenbusb_front dev.xenbusb_front.0.%desc: Xen Frontend Devices dev.xenbusb_front.%parent: dev.xs_dev.0.%parent: xenstore0 dev.xctrl.0.%parent: xenstore0 dev.xenballoon.0.%parent: xenstore0 dev.xenballoon.0.%pnpinfo: dev.xenballoon.0.%location: dev.xenballoon.0.%driver: xenballoon dev.xenballoon.0.%desc: Xen Balloon Device dev.xenballoon.%parent: dev.debug.0.%parent: xenpv0 dev.privcmd.0.%parent: xenpv0 dev.evtchn.0.%parent: xenpv0 dev.xenstore.0.%parent: xenpv0 dev.xenstore.0.%pnpinfo: dev.xenstore.0.%location: dev.xenstore.0.%driver: xenstore dev.xenstore.0.%desc: XenStore dev.xenstore.%parent: dev.xen_et.0.%parent: xenpv0 dev.xen_et.0.%pnpinfo: dev.xen_et.0.%location: dev.xen_et.0.%driver: xen_et dev.xen_et.0.%desc: Xen PV Clock dev.xen_et.%parent: dev.granttable.0.%parent: xenpv0 dev.xenpv.0.%parent: nexus0 dev.xenpv.0.%pnpinfo: dev.xenpv.0.%location: dev.xenpv.0.%driver: xenpv dev.xenpv.0.%desc: Xen PV bus dev.xenpv.%parent: dev.xenpci.0.%parent: pci0 dev.xenpci.0.%pnpinfo: vendor=3D0x5853 device=3D0x0001 subvendor=3D0x5853 = subdevice=3D0x0001 class=3D0x010000 dev.xenpci.0.%location: slot=3D3 function=3D0 dbsf=3Dpci0:0:3:0 = handle=3D\_SB_.PCI0.S18_ dev.xenpci.0.%driver: xenpci dev.xenpci.0.%desc: Xen Platform Device dev.xenpci.%parent: dev.xen.xsd_kva: 18446735281894703104 dev.xen.xsd_port: 3 dev.xen.balloon.high_mem: 0 dev.xen.balloon.low_mem: 0 dev.xen.balloon.hard_limit: 18446744073709551615 dev.xen.balloon.driver_pages: 0 dev.xen.balloon.target: 2097152 dev.xen.balloon.current: 2096128 I=E2=80=99ve tried switching the =E2=80=9EOS Type=E2=80=9C to something = like =E2=80=9Eother PV=E2=80=9C and get a bit more throughput. But = nowhere near enough to make this useful. Over at freebsd-xen, Roger thinks it looks right from the FreeBSD-side. I=E2=80=99m not the administrator of the Xen-Server itself (it=E2=80=99s = part of an Apache CloudStack private cloud cluster setup), but I can = have pretty much any setting checked/tried I need.
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