Re: Single threaded IOPS on SSD pool.

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On 6/5/19 8:44 AM, jesper@xxxxxxxx wrote:
> Hi.
> 
> This is more an inquiry to figure out how our current setup compares
> to other setups. I have a 3 x replicated SSD pool with RBD images.
> When running fio on /tmp I'm interested in seeing how much IOPS a
> single thread can get - as Ceph scales up very nicely with concurrency.
> 
> Currently 34 OSD of ~896GB Intel D3-4510's each over 7 OSD-hosts.
> 
> jk@iguana:/tmp$ for i in 01 02 03 04 05 06 07; do ping -c 10 ceph-osd$i;
> done  |egrep '(statistics|rtt)'
> --- ceph-osd01.nzcorp.net ping statistics ---
> rtt min/avg/max/mdev = 0.316/0.381/0.483/0.056 ms
> --- ceph-osd02.nzcorp.net ping statistics ---
> rtt min/avg/max/mdev = 0.293/0.415/0.625/0.100 ms
> --- ceph-osd03.nzcorp.net ping statistics ---
> rtt min/avg/max/mdev = 0.319/0.395/0.558/0.074 ms
> --- ceph-osd04.nzcorp.net ping statistics ---
> rtt min/avg/max/mdev = 0.224/0.352/0.492/0.077 ms
> --- ceph-osd05.nzcorp.net ping statistics ---
> rtt min/avg/max/mdev = 0.257/0.360/0.444/0.059 ms
> --- ceph-osd06.nzcorp.net ping statistics ---
> rtt min/avg/max/mdev = 0.209/0.334/0.442/0.062 ms
> --- ceph-osd07.nzcorp.net ping statistics ---
> rtt min/avg/max/mdev = 0.259/0.401/0.517/0.069 ms
> 
> Ok, average network latency from VM to OSD's ~0.4ms.
> 
> $ fio fio-job-randr.ini
> test: (g=0): rw=randread, bs=4K-4K/4K-4K/4K-4K, ioengine=libaio, iodepth=1
> fio-2.2.10
> Starting 1 process
> Jobs: 1 (f=1): [r(1)] [100.0% done] [2145KB/0KB/0KB /s] [536/0/0 iops]
> [eta 00m:00s]
> test: (groupid=0, jobs=1): err= 0: pid=29519: Wed Jun  5 08:40:51 2019
>   Description  : [fio random 4k reads]
>   read : io=143352KB, bw=2389.2KB/s, iops=597, runt= 60001msec
>     slat (usec): min=8, max=1925, avg=30.24, stdev=13.56
>     clat (usec): min=7, max=321039, avg=1636.47, stdev=4346.52
>      lat (usec): min=102, max=321074, avg=1667.58, stdev=4346.57
>     clat percentiles (usec):
>      |  1.00th=[  157],  5.00th=[  844], 10.00th=[  924], 20.00th=[ 1012],
>      | 30.00th=[ 1096], 40.00th=[ 1160], 50.00th=[ 1224], 60.00th=[ 1304],
>      | 70.00th=[ 1400], 80.00th=[ 1528], 90.00th=[ 1768], 95.00th=[ 2128],
>      | 99.00th=[11328], 99.50th=[18304], 99.90th=[51456], 99.95th=[94720],
>      | 99.99th=[216064]
>     bw (KB  /s): min=    0, max= 3089, per=99.39%, avg=2374.50, stdev=472.15
>     lat (usec) : 10=0.01%, 100=0.01%, 250=2.95%, 500=0.03%, 750=0.27%
>     lat (usec) : 1000=14.96%
>     lat (msec) : 2=75.87%, 4=2.99%, 10=1.78%, 20=0.73%, 50=0.30%
>     lat (msec) : 100=0.07%, 250=0.03%, 500=0.01%
>   cpu          : usr=0.76%, sys=3.29%, ctx=38871, majf=0, minf=11
>   IO depths    : 1=108.2%, 2=0.0%, 4=0.0%, 8=0.0%, 16=0.0%, 32=0.0%,
>> =64=0.0%
>      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=0.0%
>      issued    : total=r=35838/w=0/d=0, short=r=0/w=0/d=0, drop=r=0/w=0/d=0
>      latency   : target=0, window=0, percentile=100.00%, depth=1
> 
> Run status group 0 (all jobs):
>    READ: io=143352KB, aggrb=2389KB/s, minb=2389KB/s, maxb=2389KB/s,
> mint=60001msec, maxt=60001msec
> 
> Disk stats (read/write):
>   vda: ios=38631/51, merge=0/3, ticks=62668/40, in_queue=62700, util=96.77%
> 
> 
> And fio-file:
> $ cat fio-job-randr.ini
> [global]
> readwrite=randread
> blocksize=4k
> ioengine=libaio
> numjobs=1
> thread=0
> direct=1
> iodepth=1
> group_reporting=1
> ramp_time=5
> norandommap=1
> description=fio random 4k reads
> time_based=1
> runtime=60
> randrepeat=0
> 
> [test]
> size=1g
> 
> 
> Single threaded performance ~500-600 IOPS - or average latency of 1.6ms
> Is that comparable to what other are seeing?

Something <1ms is possible. I did a test last week and got 1236 IOps
with a 4k 3x write.

Think about:

- Disable Ceph logging
- Pin CPU to C-State 1
- Disable CPU powersaving

Try again!

Wido

> 
> 
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