Hi,
I am trying to use “'throttle' block filter” mentioned at
https://github.com/qemu/qemu/blob/master/docs/throttle.txt, however, it seems
not work with the following steps, did I miss or mis-understand anything?
1. In RHEL 8.8, I created one vm
qemu-kvm -m 2048 -drive file=/virt/images/focal-server-cloudimg-amd64.img
-drive file=/virt/disks/vm1_disk_1.qcow2 -drive
file=/virt/disks/vm1_disk_2.qcow2 -serial stdio -vga virtio -display default
-qmp tcp:localhost:4444,server,wait=off
2. telnet vm
telnet localhost 4444
{"execute": "qmp_capabilities"}
3. add a new data disk ()
{"execute": "blockdev-add", "arguments": {"node-name": "disk7", "driver":
"qcow2", "file": {"driver": "file", "filename":
"/virt/disks/vm1_disk_7.qcow2"}}}
4. create a new throttle group
{"execute": "object-add", "arguments": {"qom-type": "throttle-group", "id":
"limit1", "limits": {"iops-total": 1000}}}
5. add a throttle filter to disk
{"execute": "blockdev-add", "arguments": {"driver": "throttle", "node-name":
"throttle1", "throttle-group": "limit1", "file": "disk7"}}
6. associate the disk with vm
{"execute": "device_add", "arguments": {"driver": "virtio-blk", "id": "blk7",
"drive": "disk7"}}
7. fio test within vm (limit is 1000, while fio gets 2445 in avg)
fio --name=mytest --ioengine=sync --rw=randwrite --bs=4k --size=20G --numjobs=1
--time_based --runtime=300s --filename=/dev/vda
mytest: (g=0): rw=randwrite, bs=(R) 4096B-4096B, (W) 4096B-4096B, (T)
4096B-4096B, ioengine=sync, iodepth=1
fio-3.16
Starting 1 process
Jobs: 1 (f=1): [f(1)][100.0%][eta 00m:00s]
mytest: (groupid=0, jobs=1): err= 0: pid=959: Tue Oct 24 15:11:38 2023
write: IOPS=2446, BW=9784KiB/s (10.0MB/s)(2867MiB/300016msec); 0 zone resets
clat (usec): min=3, max=131566, avg=399.31, stdev=3128.70
lat (usec): min=4, max=131568, avg=401.12, stdev=3128.72
clat percentiles (usec):
| 1.00th=[ 5], 5.00th=[ 6], 10.00th=[ 6], 20.00th=[ 6],
| 30.00th=[ 6], 40.00th=[ 7], 50.00th=[ 7], 60.00th=[ 8],
| 70.00th=[ 10], 80.00th=[ 11], 90.00th=[ 29], 95.00th=[ 94],
| 99.00th=[23462], 99.50th=[23987], 99.90th=[31589], 99.95th=[33817],
| 99.99th=[43779]
bw ( KiB/s): min= 896, max=248856, per=99.98%, avg=9781.85,
stdev=26238.98, samples=600
iops : min= 224, max=62214, avg=2445.43, stdev=6559.75, samples=600
lat (usec) : 4=0.01%, 10=76.84%, 20=11.91%, 50=3.37%, 100=3.29%
lat (usec) : 250=2.49%, 500=0.33%, 750=0.07%, 1000=0.04%
lat (msec) : 2=0.04%, 4=0.02%, 10=0.02%, 20=0.33%, 50=1.24%
lat (msec) : 100=0.01%, 250=0.01%
cpu : usr=1.32%, sys=4.32%, ctx=23971, majf=0, minf=11
IO depths : 1=100.0%, 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 rwts: total=0,733855,0,0 short=0,0,0,0 dropped=0,0,0,0
latency : target=0, window=0, percentile=100.00%, depth=1
Run status group 0 (all jobs):
WRITE: bw=9784KiB/s (10.0MB/s), 9784KiB/s-9784KiB/s (10.0MB/s-10.0MB/s),
io=2867MiB (3006MB), run=300016-300016msec
Disk stats (read/write):
vda: ios=0/660825, merge=0/17257, ticks=0/39116357, in_queue=38236828,
util=98.23%
