Il giorno 2 set 2019, alle ore 17:56, Tejun Heo [off-list ref] ha scritto:

On Mon, Sep 02, 2019 at 05:45:50PM +0200, Paolo Valente wrote:

quoted

Thanks for this extra explanations.  It is a little bit difficult for
me to understand how the min/max teaks for exactly, but you did give
me the general idea.

It just limits how far high and low the IO issue rate, measured in
cost, can go.  ie. if max is at 200%, the controller won't issue more
than twice of what the cost model says 100% is.

quoted

Are these results in line with your expectations?  If they are, then
I'd like to extend benchmarks to more mixes of workloads.  Or should I
try some other QoS configuration first?

They aren't.  Can you please include the content of io.cost.qos and
io.cost.model before each run?  Note that partial writes to subset of
parameters don't clear other parameters.

Yep.  I've added the printing of the two parameters in the script, and
I'm pasting the whole output, in case you could get also some other
useful piece of information from it.

$ sudo ./bandwidth-latency.sh -t randread -s none -b weight -n 7 -d 20
Switching to none for sda
echo "8:0 enable=1 rpct=95 rlat=2500 wpct=95 wlat=5000" > /cgroup/io.cost.qos
/cgroup/io.cost.qos 8:0 enable=1 ctrl=user rpct=95.00 rlat=2500 wpct=95.00 wlat=5000 min=1.00 max=10000.00
/cgroup/io.cost.model 8:0 ctrl=auto model=linear rbps=488636629 rseqiops=8932 rrandiops=8518 wbps=427891549 wseqiops=28755 wrandiops=21940
Not changing weight/limits for interferer group 0
Not changing weight/limits for interferer group 1
Not changing weight/limits for interferer group 2
Not changing weight/limits for interferer group 3
Not changing weight/limits for interferer group 4
Not changing weight/limits for interferer group 5
Not changing weight/limits for interferer group 6
Not changing weight/limits for interfered
Starting Interferer group 0
start_fio_jobs InterfererGroup0 0 default read MAX linear 1 1 0 0 4k /home/paolo/local-S/bandwidth-latency/../workfiles/largefile0
Starting Interferer group 1
start_fio_jobs InterfererGroup1 0 default read MAX linear 1 1 0 0 4k /home/paolo/local-S/bandwidth-latency/../workfiles/largefile1
Starting Interferer group 2
start_fio_jobs InterfererGroup2 0 default read MAX linear 1 1 0 0 4k /home/paolo/local-S/bandwidth-latency/../workfiles/largefile2
Starting Interferer group 3
start_fio_jobs InterfererGroup3 0 default read MAX linear 1 1 0 0 4k /home/paolo/local-S/bandwidth-latency/../workfiles/largefile3
Starting Interferer group 4
start_fio_jobs InterfererGroup4 0 default read MAX linear 1 1 0 0 4k /home/paolo/local-S/bandwidth-latency/../workfiles/largefile4
Starting Interferer group 5
start_fio_jobs InterfererGroup5 0 default read MAX linear 1 1 0 0 4k /home/paolo/local-S/bandwidth-latency/../workfiles/largefile5
Starting Interferer group 6
start_fio_jobs InterfererGroup6 0 default read MAX linear 1 1 0 0 4k /home/paolo/local-S/bandwidth-latency/../workfiles/largefile6
Linux 5.3.0-rc6+ (paolo-ThinkPad-W520) 	02/09/2019 	_x86_64_	(8 CPU)

02/09/2019 21:39:11
Device             tps    MB_read/s    MB_wrtn/s    MB_read    MB_wrtn
sda              66.53         5.22         0.10       1385         27

start_fio_jobs interfered 20 default randread MAX poisson 1 1 0 0 4k /home/paolo/local-S/bandwidth-latency/../workfiles/largefile_interfered0
02/09/2019 21:39:14
Device             tps    MB_read/s    MB_wrtn/s    MB_read    MB_wrtn
sda             154.67        20.63         0.05         61          0

02/09/2019 21:39:17
Device             tps    MB_read/s    MB_wrtn/s    MB_read    MB_wrtn
sda             453.00        64.27         0.00        192          0

02/09/2019 21:39:20
Device             tps    MB_read/s    MB_wrtn/s    MB_read    MB_wrtn
sda             675.33        95.99         0.00        287          0

02/09/2019 21:39:23
Device             tps    MB_read/s    MB_wrtn/s    MB_read    MB_wrtn
sda            1907.67       348.61         0.00       1045          0

02/09/2019 21:39:26
Device             tps    MB_read/s    MB_wrtn/s    MB_read    MB_wrtn
sda            2414.67       462.98         0.00       1388          0

02/09/2019 21:39:29
Device             tps    MB_read/s    MB_wrtn/s    MB_read    MB_wrtn
sda            2429.67       438.71         0.00       1316          0

02/09/2019 21:39:32
Device             tps    MB_read/s    MB_wrtn/s    MB_read    MB_wrtn
sda            2437.00       475.79         0.00       1427          0

02/09/2019 21:39:35
Device             tps    MB_read/s    MB_wrtn/s    MB_read    MB_wrtn
sda            2162.33       346.97         0.00       1040          0

Results for one rand reader against 7 seq readers (I/O depth 1), weight-none with weights: (default, default)
Aggregated throughput:
         min         max         avg     std_dev     conf99%
       64.27      475.79     319.046     171.233     1011.97
Read throughput:
         min         max         avg     std_dev     conf99%
       64.27      475.79     319.046     171.233     1011.97
Write throughput:
         min         max         avg     std_dev     conf99%
           0           0           0           0           0
Interfered total throughput:
         min         max         avg     std_dev
       1.032       4.455       2.266    0.742696
Interfered per-request total latency:
         min         max         avg     std_dev
        0.11      12.005      1.7545    0.878281

Thanks,
Paolo

Thanks.

-- 
tejun