btw, we use perf to track the process qemu-system-x86(15801), there is an
abnormal function:
Samples: 1M of event 'cycles', Event count (approx.): 1057109744252
- 75.23% qemu-system-x86 [kernel.kallsyms] [k] do_raw_spin_lock
- do_raw_spin_lock
+ 54.44% 0x7fc79fc769d9
+ 45.31% 0x7fc79fc769ab
So, maybe it's the kvm problem?
[email protected]
From: [email protected]
Date: 2015-10-23 11:54
To: Alexandre DERUMIER
CC: ceph-users
Subject: Re: Re: [ceph-users] [performance] rbd kernel module versus qemu librbd
Hi, list
We still stuck on this problem, when this problem comes, the CPU usage of
qemu-system-x86 if very high(1420):
15801 libvirt- 20 0 33.7g 1.4g 11m R 1420 0.6 1322:26 qemu-system-x86
quem-system-x86 process 15801 is responsible for the VM.
Anyone has ever run into this problem also.
[email protected]
From: [email protected]
Date: 2015-10-22 10:15
To: Alexandre DERUMIER
CC: ceph-users
Subject: Re: Re: [ceph-users] [performance] rbd kernel module versus qemu librbd
Hi,
Sure, all those could help, but not so much -:)
Now, we find it's the VM problem. CPU on the host is very high.
We create a new VM could solve this problem, but don't know why until now.
Here is the detail version info:
Compiled against library: libvirt 1.2.9
Using library: libvirt 1.2.9
Using API: QEMU 1.2.9
Running hypervisor: QEMU 2.1.2
Are there any already know bugs about those version?
Thanks!
[email protected]
From: Alexandre DERUMIER
Date: 2015-10-21 18:38
To: hzwulibin
CC: ceph-users
Subject: Re: [ceph-users] [performance] rbd kernel module versus qemu librbd
here a libvirt sample to enable iothreads:
<domain>
<iothreads>2</iothreads>
<disk type='file' device='disk'>
<driver name='qemu' type='raw' iothread='1'/>
<source file='/var/lib/libvirt/images/iothrtest1.img'/>
<target dev='vda' bus='virtio'/>
</disk>
<disk type='file' device='disk'>
<driver name='qemu' type='raw' iothread='2'/>
<source file='/var/lib/libvirt/images/iothrtest2.img'/>
<target dev='vdb' bus='virtio'/>
</disk>
</domain>
With this, you can scale with multiple disks. (but it should help a little bit
with 1 disk too)
----- Mail original -----
De: [email protected]
À: "aderumier" <[email protected]>
Cc: "ceph-users" <[email protected]>
Envoyé: Mercredi 21 Octobre 2015 10:31:56
Objet: Re: [ceph-users] [performance] rbd kernel module versus qemu librbd
Hi,
let me post the version and configuration here first.
host os: debian 7.8 kernel: 3.10.45
guest os: debian 7.8 kernel: 3.2.0-4
qemu version:
ii ipxe-qemu 1.0.0+git-20131111.c3d1e78-2.1~bpo70+1 all PXE boot firmware - ROM
images for qemu
ii qemu-kvm 1:2.1+dfsg-12~bpo70+1 amd64 QEMU Full virtualization on x86
hardware
ii qemu-system-common 1:2.1+dfsg-12~bpo70+1 amd64 QEMU full system emulation
binaries (common files)
ii qemu-system-x86 1:2.1+dfsg-12~bpo70+1 amd64 QEMU full system emulation
binaries (x86)
ii qemu-utils 1:2.1+dfsg-12~bpo70+1 amd64 QEMU utilities
vm config:
<disk type='network' device='disk'>
<driver name='qemu' type='raw' cache='none'/>
<auth username='cinder'>
<secret type='ceph' uuid='****'/>
</auth>
<source protocol='rbd' name='*****'>
<host name='***' port='6789'/>
<host name='***' port='6789'/>
<host name='***' port='6789'/>
</source>
<target dev='vdf' bus='virtio'/>
<serial>*******</serial>
<address type='pci' domain='0x0000' bus='0x00' slot='0x1d' function='0x0'/>
</disk>
Thanks!
[email protected]
From: Alexandre DERUMIER
Date: 2015-10-21 14:01
To: hzwulibin
CC: ceph-users
Subject: Re: [ceph-users] [performance] rbd kernel module versus qemu librbd
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: [email protected]
À: "aderumier" <[email protected]>
Cc: "ceph-users" <[email protected]>
Envoyé: Mercredi 21 Octobre 2015 06:11:20
Objet: Re: Re: [ceph-users] [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!
[email protected]
From: Alexandre DERUMIER
Date: 2015-10-20 19:36
To: hzwulibin
CC: ceph-users
Subject: Re: [ceph-users] [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: [email protected]
À: "ceph-users" <[email protected]>
Envoyé: Mardi 20 Octobre 2015 10:22:33
Objet: [ceph-users] [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!
[email protected]
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