Damn, that's a huge difference. What is your host os, guest os , qemu version and vm config ? As an extra boost, you could enable iothread on virtio disk. (It's available on libvirt but not on openstack yet). If it's a test server, maybe could you test it with proxmox 4.0 hypervisor https://www.proxmox.com I have made a lot of patch inside it to optimize rbd (qemu+jemalloc, iothreads,...) ----- Mail original ----- De: hzwulibin@xxxxxxxxx À: "aderumier" <aderumier@xxxxxxxxx> Cc: "ceph-users" <ceph-users@xxxxxxxx> Envoyé: Mercredi 21 Octobre 2015 06:11:20 Objet: Re: Re: [performance] rbd kernel module versus qemu librbd Hi, Thanks for you reply. I do more test here and things change more strange, now i only could get about 4k iops in VM: 1. use fio with ioengine rbd to test the volume on the real machine [global] ioengine=rbd clientname=admin pool=vol_ssd rbdname=volume-4f4f9789-4215-4384-8e65-127a2e61a47f rw=randwrite bs=4k group_reporting=1 [rbd_iodepth32] iodepth=32 [rbd_iodepth1] iodepth=32 [rbd_iodepth28] iodepth=32 [rbd_iodepth8] iodepth=32 could achive about 18k iops. 2. test the same volume in VM, achive about 4.3k iops [global] rw=randwrite bs=4k ioengine=libaio #ioengine=sync iodepth=128 direct=1 group_reporting=1 thread=1 filename=/dev/vdb [task1] iodepth=32 [task2] iodepth=32 [task3] iodepth=32 [task4] iodepth=32 Using cep osd perf to check the osd latency, all less than 1 ms. Using iostat to check the osd %util, about 10 in case 2 test. Using dstat to check VM status: ----total-cpu-usage---- -dsk/total- -net/total- ---paging-- ---system-- usr sys idl wai hiq siq| read writ| recv send| in out | int csw 2 4 51 43 0 0| 0 17M| 997B 3733B| 0 0 |3476 6997 2 5 51 43 0 0| 0 18M| 714B 4335B| 0 0 |3439 6915 2 5 50 43 0 0| 0 17M| 594B 3150B| 0 0 |3294 6617 1 3 52 44 0 0| 0 18M| 648B 3726B| 0 0 |3447 6991 1 5 51 43 0 0| 0 18M| 582B 3208B| 0 0 |3467 7061 Finally, using iptraf to check the package size in the VM, almost packages's size are around 1 to 70 and 71 to 140 bytes. That's different from real machine. But maybe iptraf on the VM can't prove anything, i check the real machine which the VM located on. It seems no abnormal. BTW, my VM is located on the ceph storage node. Anyone can give me more sugestions? Thanks! hzwulibin@xxxxxxxxx From: Alexandre DERUMIER Date: 2015-10-20 19:36 To: hzwulibin CC: ceph-users Subject: Re: [performance] rbd kernel module versus qemu librbd Hi, I'm able to reach around same performance with qemu-librbd vs qemu-krbd, when I compile qemu with jemalloc (http://git.qemu.org/?p=qemu.git;a=commit;h=7b01cb974f1093885c40bf4d0d3e78e27e531363) on my test, librbd with jemalloc still use 2x more cpu than krbd, so cpu could be bottleneck too. with fasts cpu (3.1ghz), I'm able to reach around 70k iops 4k with rbd volume, both with krbd or librbd ----- Mail original ----- De: hzwulibin@xxxxxxxxx À: "ceph-users" <ceph-users@xxxxxxxx> Envoyé: Mardi 20 Octobre 2015 10:22:33 Objet: [performance] rbd kernel module versus qemu librbd Hi, I have a question about the IOPS performance for real machine and virtual machine. Here is my test situation: 1. ssd pool (9 OSD servers with 2 osds on each server, 10Gb networks for public & cluster networks) 2. volume1: use rbd create a 100G volume from the ssd pool and map to the real machine 3. volume2: use cinder create a 100G volume form the ssd pool and atach to a guest host 4. disable rbd cache 5. fio test on the two volues: [global] rw=randwrite bs=4k ioengine=libaio iodepth=64 direct=1 size=64g runtime=300s group_reporting=1 thread=1 volume1 got about 24k IOPS and volume got about 14k IOPS. We could see performance of volume2 is not good compare to volume1, so is it normal behabior of guest host? If not, what maybe the problem? Thanks! hzwulibin@xxxxxxxxx _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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