On 2/4/2019 12:21 AM, john.hubbard@xxxxxxxxx wrote:
From: John Hubbard <jhubbard@xxxxxxxxxx>
Performance: here is an fio run on an NVMe drive, using this for the fio
configuration file:
[reader]
direct=1
ioengine=libaio
blocksize=4096
size=1g
numjobs=1
rw=read
iodepth=64
reader: (g=0): rw=read, bs=(R) 4096B-4096B, (W) 4096B-4096B, (T) 4096B-4096B, ioengine=libaio, iodepth=64
fio-3.3
Starting 1 process
Jobs: 1 (f=1)
reader: (groupid=0, jobs=1): err= 0: pid=7011: Sun Feb 3 20:36:51 2019
read: IOPS=190k, BW=741MiB/s (778MB/s)(1024MiB/1381msec)
slat (nsec): min=2716, max=57255, avg=4048.14, stdev=1084.10
clat (usec): min=20, max=12485, avg=332.63, stdev=191.77
lat (usec): min=22, max=12498, avg=336.72, stdev=192.07
clat percentiles (usec):
| 1.00th=[ 322], 5.00th=[ 322], 10.00th=[ 322], 20.00th=[ 326],
| 30.00th=[ 326], 40.00th=[ 326], 50.00th=[ 326], 60.00th=[ 326],
| 70.00th=[ 326], 80.00th=[ 330], 90.00th=[ 330], 95.00th=[ 330],
| 99.00th=[ 478], 99.50th=[ 717], 99.90th=[ 1074], 99.95th=[ 1090],
| 99.99th=[12256]
These latencies are concerning. The best results we saw at the end of
November (previous approach) were MUCH flatter. These really start
spiking at three 9's, and are sky-high at four 9's. The "stdev" values
for clat and lat are about 10 times the previous. There's some kind
of serious queuing contention here, that wasn't there in November.
bw ( KiB/s): min=730152, max=776512, per=99.22%, avg=753332.00, stdev=32781.47, samples=2
iops : min=182538, max=194128, avg=188333.00, stdev=8195.37, samples=2
lat (usec) : 50=0.01%, 100=0.01%, 250=0.07%, 500=99.26%, 750=0.38%
lat (usec) : 1000=0.02%
lat (msec) : 2=0.24%, 20=0.02%
cpu : usr=15.07%, sys=84.13%, ctx=10, majf=0, minf=74
System CPU 84% is roughly double the November results of 45%. Ouch.
Did you re-run the baseline on the new unpatched base kernel and can
we see the before/after?
Tom.
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=0.1%, >=64=0.0%
issued rwts: total=262144,0,0,0 short=0,0,0,0 dropped=0,0,0,0
latency : target=0, window=0, percentile=100.00%, depth=64
Run status group 0 (all jobs):
READ: bw=741MiB/s (778MB/s), 741MiB/s-741MiB/s (778MB/s-778MB/s), io=1024MiB (1074MB), run=1381-1381msec
Disk stats (read/write):
nvme0n1: ios=216966/0, merge=0/0, ticks=6112/0, in_queue=704, util=91.34%
