Re: All SSD Pool - Odd Performance

[Udo Lembke <ulembke@xxxxxxxxxxxx>]

Hi Sean,
Haomai is right, that qemu can have a huge performance differences.

I have done two test to the same ceph-cluster (different pools, but this should not do any differences).
One test with proxmox ve 4 (qemu 2.4, iothread for device, and cache=writeback) gives 14856 iops
Same test with proxmox ve 3.4 (qemu 2.2.1, cache=writethrough) gives 5070 iops only.

Here the results in long:
############### proxmox ve 3.x ###############
kvm --version
QEMU emulator version 2.2.1, Copyright (c) 2003-2008 Fabrice Bellard

VM:
virtio2: ceph_file:vm-405-disk-1,cache=writethrough,backup=no,size=4096G

root@fileserver:/daten/support/test# fio --time_based --name=benchmark --size=4G --filename=/mnt/test.bin --ioengine=libaio --randrepeat=0 --iodepth=128 --direct=1 --invalidate=1 --verify=0 --verify_fatal=0 --numjobs=4 --rw=randwrite --blocksize=4k --group_reporting
fio: time_based requires a runtime/timeout setting
benchmark: (g=0): rw=randwrite, bs=4K-4K/4K-4K/4K-4K, ioengine=libaio, iodepth=128
...
fio-2.1.11
Starting 4 processes
benchmark: Laying out IO file(s) (1 file(s) / 4096MB)
Jobs: 1 (f=1): [_(1),w(1),_(2)] [100.0% done] [0KB/40024KB/0KB /s] [0/10.6K/0 iops] [eta 00m:00s]
benchmark: (groupid=0, jobs=4): err= 0: pid=7821: Sun Nov 22 04:07:47 2015
  write: io=16384MB, bw=20282KB/s, iops=5070, runt=827178msec
    slat (usec): min=0, max=2531.7K, avg=778.68, stdev=12757.26
    clat (usec): min=508, max=2755.2K, avg=99980.14, stdev=146967.17
     lat (msec): min=1, max=2755, avg=100.76, stdev=147.54
    clat percentiles (msec):
     |  1.00th=[   10],  5.00th=[   14], 10.00th=[   19], 20.00th=[   28],
     | 30.00th=[   36], 40.00th=[   43], 50.00th=[   51], 60.00th=[   63],
     | 70.00th=[   81], 80.00th=[  128], 90.00th=[  237], 95.00th=[  367],
     | 99.00th=[  717], 99.50th=[  889], 99.90th=[ 1516], 99.95th=[ 1713],
     | 99.99th=[ 2573]
    bw (KB  /s): min=    4, max=30726, per=26.90%, avg=5456.84, stdev=3014.45
    lat (usec) : 750=0.01%, 1000=0.01%
    lat (msec) : 2=0.01%, 4=0.01%, 10=1.11%, 20=10.18%, 50=37.74%
    lat (msec) : 100=26.45%, 250=15.22%, 500=6.66%, 750=1.74%, 1000=0.55%
    lat (msec) : 2000=0.29%, >=2000=0.03%
  cpu          : usr=0.36%, sys=2.31%, ctx=1148702, majf=0, minf=30
  IO depths    : 1=0.1%, 2=0.1%, 4=0.1%, 8=0.1%, 16=0.1%, 32=0.1%, >=64=100.0%
     submit    : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
     complete  : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.1%
     issued    : total=r=0/w=4194304/d=0, short=r=0/w=0/d=0
     latency   : target=0, window=0, percentile=100.00%, depth=128

Run status group 0 (all jobs):
  WRITE: io=16384MB, aggrb=20282KB/s, minb=20282KB/s, maxb=20282KB/s, mint=827178msec, maxt=827178msec

Disk stats (read/write):
    dm-0: ios=0/4483641, merge=0/0, ticks=0/104928824, in_queue=105927128, util=100.00%, aggrios=1/4469640, aggrmerge=0/14788, aggrticks=64/103711096, aggrin_queue=104165356, aggrutil=100.00%
  vda: ios=1/4469640, merge=0/14788, ticks=64/103711096, in_queue=104165356, util=100.00%

##############################################

############### proxmox ve 4.x ###############
kvm --version
QEMU emulator version 2.4.0.1 pve-qemu-kvm_2.4-12, Copyright (c) 2003-2008 Fabrice Bellard

grep ceph /etc/pve/qemu-server/102.conf
virtio1: ceph_test:vm-102-disk-1,cache=writeback,iothread=on,size=100G

root@fileserver-test:/daten/tv01/test# fio --time_based --name=benchmark --size=4G --filename=/mnt/test.bin --ioengine=libaio --randrepeat=0 --iodepth=128 --direct=1 --invalidate=1 --verify=0 --verify_fatal=0 --numjobs=4 --rw=randwrite --blocksize=4k --group_reporting          
fio: time_based requires a runtime/timeout setting                                                                                      
benchmark: (g=0): rw=randwrite, bs=4K-4K/4K-4K/4K-4K, ioengine=libaio, iodepth=128                                                             
...                                                                                                                                                
fio-2.1.11
Starting 4 processes
Jobs: 4 (f=4): [w(4)] [99.6% done] [0KB/56148KB/0KB /s] [0/14.4K/0 iops] [eta 00m:01s]
benchmark: (groupid=0, jobs=4): err= 0: pid=26131: Sun Nov 22 03:51:04 2015
  write: io=0B, bw=59425KB/s, iops=14856, runt=282327msec
    slat (usec): min=6, max=216925, avg=261.78, stdev=1802.78
    clat (msec): min=1, max=330, avg=34.04, stdev=27.78
     lat (msec): min=1, max=330, avg=34.30, stdev=27.87
    clat percentiles (msec):
     |  1.00th=[   10],  5.00th=[   13], 10.00th=[   14], 20.00th=[   16],
     | 30.00th=[   18], 40.00th=[   19], 50.00th=[   21], 60.00th=[   24],
     | 70.00th=[   33], 80.00th=[   62], 90.00th=[   81], 95.00th=[   87],
     | 99.00th=[   95], 99.50th=[  100], 99.90th=[  269], 99.95th=[  277],
     | 99.99th=[  297]
    bw (KB  /s): min=    3, max=42216, per=25.10%, avg=14917.03, stdev=2990.50
    lat (msec) : 2=0.01%, 4=0.01%, 10=1.13%, 20=45.52%, 50=28.23%
    lat (msec) : 100=24.61%, 250=0.35%, 500=0.16%
  cpu          : usr=2.20%, sys=14.42%, ctx=2462199, majf=0, minf=40
  IO depths    : 1=0.1%, 2=0.1%, 4=0.1%, 8=0.1%, 16=0.1%, 32=0.1%, >=64=100.0%
     submit    : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
     complete  : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.1%
     issued    : total=r=0/w=4194304/d=0, short=r=0/w=0/d=0
     latency   : target=0, window=0, percentile=100.00%, depth=128

Run status group 0 (all jobs):
  WRITE: io=16384MB, aggrb=59424KB/s, minb=59424KB/s, maxb=59424KB/s, mint=282327msec, maxt=282327msec

Disk stats (read/write):
    dm-0: ios=0/4192044, merge=0/0, ticks=0/35093432, in_queue=35116888, util=99.70%, aggrios=0/4194626, aggrmerge=0/14, aggrticks=0/34902692, aggrin_queue=34903976, aggrutil=99.65%
  vda: ios=0/4194626, merge=0/14, ticks=0/34902692, in_queue=34903976, util=99.65%
##############################################

regards

Udo

On 19.11.2015 11:46, Sean Redmond wrote:

Hi Mike/Warren,

Thanks for helping out here. I am running the below fio command to test this with 4 jobs and a iodepth of 128

fio --time_based --name=benchmark --size=4G --filename=/mnt/test.bin --ioengine=libaio --randrepeat=0 --iodepth=128 --direct=1 --invalidate=1 --verify=0 --verify_fatal=0 --numjobs=4 --rw=randwrite --blocksize=4k --group_reportin

The QEMU instance is created using nova, the settings I can see in the config are below:

    <disk type='network' device='disk'>

      <driver name='qemu' type='raw' cache='writeback'/>

      <auth username='$$'>

        <secret type='ceph' uuid='$$'/>

      </auth>

      <source protocol='rbd' name='ssd_volume/volume-$$'>

        <host name='$$' port='6789'/>

        <host name='$$' port='6789'/>

        <host name='$$' port='6789'/>

      </source>

      <target dev='vde' bus='virtio'/>

      <serial>$$</serial>

      <address type='pci' domain='0x0000' bus='0x00' slot='0x09' function='0x0'/>

    </disk>

The below shows the output from running Fio:

# fio --time_based --name=benchmark --size=4G --filename=/mnt/test.bin --ioengine=libaio --randrepeat=0 --iodepth=128 --direct=1 --invalidate=1 --verify=0 --verify_fatal=0 --numjobs=4 --rw=randwrite --blocksize=4k --group_reporting

fio: time_based requires a runtime/timeout setting

benchmark: (g=0): rw=randwrite, bs=4K-4K/4K-4K/4K-4K, ioengine=libaio, iodepth=128

...

benchmark: (g=0): rw=randwrite, bs=4K-4K/4K-4K/4K-4K, ioengine=libaio, iodepth=128

fio-2.0.13

Starting 4 processes

Jobs: 3 (f=3): [_www] [99.7% done] [0K/36351K/0K /s] [0 /9087 /0  iops] [eta 00m:03s]

benchmark: (groupid=0, jobs=4): err= 0: pid=8547: Thu Nov 19 05:16:31 2015

  write: io=16384MB, bw=19103KB/s, iops=4775 , runt=878269msec

    slat (usec): min=4 , max=2339.4K, avg=807.17, stdev=12460.02

    clat (usec): min=1 , max=2469.6K, avg=106265.05, stdev=138893.39

     lat (usec): min=67 , max=2469.8K, avg=107073.04, stdev=139377.68

    clat percentiles (usec):

     |  1.00th=[ 1928],  5.00th=[ 9408], 10.00th=[12352], 20.00th=[18816],

     | 30.00th=[43776], 40.00th=[64768], 50.00th=[78336], 60.00th=[89600],

     | 70.00th=[102912], 80.00th=[123392], 90.00th=[216064], 95.00th=[370688],

     | 99.00th=[733184], 99.50th=[782336], 99.90th=[1044480], 99.95th=[2088960],

     | 99.99th=[2342912]

    bw (KB/s)  : min=    4, max=14968, per=26.11%, avg=4987.39, stdev=1947.67

    lat (usec) : 2=0.01%, 20=0.01%, 50=0.01%, 100=0.05%, 250=0.30%

    lat (usec) : 500=0.24%, 750=0.11%, 1000=0.08%

    lat (msec) : 2=0.23%, 4=0.46%, 10=4.47%, 20=15.08%, 50=11.28%

    lat (msec) : 100=35.47%, 250=23.52%, 500=5.92%, 750=1.96%, 1000=0.70%

    lat (msec) : 2000=0.06%, >=2000=0.06%

  cpu          : usr=0.62%, sys=2.42%, ctx=1602209, majf=1, minf=101

  IO depths    : 1=0.1%, 2=0.1%, 4=0.1%, 8=0.1%, 16=0.1%, 32=0.1%, >=64=100.0%

     submit    : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%

     complete  : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.1%

     issued    : total=r=0/w=4194304/d=0, short=r=0/w=0/d=0

Run status group 0 (all jobs):

  WRITE: io=16384MB, aggrb=19102KB/s, minb=19102KB/s, maxb=19102KB/s, mint=878269msec, maxt=878269msec

Disk stats (read/write):

  vde: ios=1119/4330437, merge=0/105599, ticks=556/121755054, in_queue=121749666, util=99.86

The below shows lspci from within the guest:

# lspci | grep -i scsi

00:04.0 SCSI storage controller: Red Hat, Inc Virtio block devic

Thanks

On Wed, Nov 18, 2015 at 7:05 PM, Warren Wang - ISD <Warren.Wang@xxxxxxxxxxx> wrote:

What were you using for iodepth and numjobs? If you’re getting an average of 2ms per operation, and you’re single threaded, I’d expect about 500 IOPS / thread, until you hit the limit of your QEMU setup, which may be a single IO thread. That’s also what I think Mike is alluding to.

Warren

From: Sean Redmond <sean.redmond1@xxxxxxxxx<mailto:sean.redmond1@xxxxxxxxx>>
Date: Wednesday, November 18, 2015 at 6:39 AM
To: "ceph-users@xxxxxxxx<mailto:ceph-users@xxxxxxxx>" <ceph-users@xxxxxxxx<mailto:ceph-users@xxxxxxxx>>
Subject: All SSD Pool - Odd Performance

Hi,

I have a performance question for anyone running an SSD only pool. Let me detail the setup first.

12 X Dell PowerEdge R630 ( 2 X 2620v3 64Gb RAM)
8 X intel DC 3710 800GB
Dual port Solarflare 10GB/s NIC (one front and one back)
Ceph 0.94.5
Ubuntu 14.04 (3.13.0-68-generic)

The above is in one pool that is used for QEMU guests, A 4k FIO test on the SSD directly yields around 55k Iops, the same test inside a QEMU guest seems to hit a limit around 4k Iops. If I deploy multiple guests they can all reach 4K Iops simultaneously.

I don't see any evidence of a bottle neck on the OSD hosts,Is this limit inside the guest expected or I am just not looking deep enough yet?

Thanks

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