Do we understand the performance of UDA?

[DavidPCoster]

I have been looking at the performance of UDA in getting an entire IDS -- in this case the summary IDS.

I have been using uda.py (https://gitlab.eufus.psnc.pl/data-access-tools/uda-test) for these tests.

The data resides at ITER and I have accessed it (1) directly from ITER using the UDA bypass feature, (2) using UDA at ITER talking to the ITER UDA server, and (3) using UDA on the EUROfusion Gateway talking to the ITER UDA server. The results are summarized below:

In all cases the command executed is
./uda.py -u 'imas://uda.iter.org:56565/uda?path=/work/imas/shared/imasdb/ITER/3/134174/117&backend=mdsplus' -c summary

At ITER
With bypass enabled ($IMAS_LOCAL_HOSTS == uda.iter.org)
    DBentry =  1.012    DBentry =  0.967    DBentry =  0.972
        get =  0.488        get =  0.125        get =  0.135
      close =  0.002      close =  0.001      close =  0.002
With bypass disabled ($IMAS_LOCAL_HOSTS == '')
    DBentry =  1.421    DBentry =  1.325    DBentry =  1.370
        get = 94.286        get = 83.453        get = 80.465
      close =  0.005      close =  0.004      close =  0.003
At Gateway
    DBentry =  1.345    DBentry =  1.384    DBentry =  1.271 
        get = 96.223        get = 95.684        get = 100.322
      close =  0.038      close =  0.036      close =  0.037 

Concentrating on the data "get" operation, we see:

1. Direct access is more than 300 times faster
2. Remote access occurs a penalty of about 13% compared to local UDA access

Do we understand why accessing the data over the network is so much slower?

I also looked at a bigger IDS, and saw

./uda.py -u 'imas://uda.iter.org:56565/uda?path=/work/imas/shared/imasdb/ITER/3/134174/117&backend=mdsplus' -c equilibrium
From ITER
with $IMAS_LOCAL_HOSTS == uda.iter.org
    DBentry =  1.029
        get =  0.794
      close =  0.000
with $IMAS_LOCAL_HOSTS == ''
    DBentry =  1.591
        get = 16284.980
      close =  0.003
From Gateway
Timing information
    DBentry =  2.039
        get = 24115.763
      close =  0.036

Which gives:

1. UDA (local) / local : 20510.05
2. UDA (Gateway) / UDA (local) : 1.481

[cenkoloji]

Out of curiosity, checking the same in my local IMAS/UDA server. Difference is about 10 times.

yildiz@spcimas: ~  $ ./uda.py -u 'imas:mdsplus?path=/data/imas/public/imasdb/tcv/3/71222/999/' -c summary 2>/dev/null |grep "get ="
        get =  0.059
        
yildiz@spcimas: ~  $ IMAS_LOCAL_HOSTS="localhost" ./uda.py -u 'imas://localhost:56565/uda?path=/data/imas/public/imasdb/tcv/3/71222/999/&backend=mdsplus' -c summary  2>/dev/null |grep "get ="
        get =  0.059
        
yildiz@spcimas: ~  $ ./uda.py -u 'imas://localhost:56565/uda?path=/data/imas/public/imasdb/tcv/3/71222/999/&backend=mdsplus' -c summary  2>/dev/null |grep "get ="
        get =  0.487

software versions:

yildiz@spcimas: ~  $ module list
Currently Loaded Modulefiles:
 1) IMAS/3.39.0-5.0.0   2) idstools/1.14.1   3) uda/2.7.4  

Info for the ones that haven't checked what IMAS_LOCAL_HOSTS does: it removes uda backend and sets the backend from the uda arguments. That's why the first and second calls are in fact identical. (access-layer/lowlevel/al_context.cpp#192)

[DavidPCoster]

@cenkoloji -- How big were the IDSes you accessed?

In my case

Reading 48.138 MB of data for equilibrium/0 took 2.01 seconds
Reading 0.061 MB of data for summary/0 took 0.14 seconds

using the "idssize" command of the soon to be released idstools (release/2.0.0)

[cenkoloji]

This example was just summary. I can't run idssize as the imas version I have isn't compatible yet. but summary and equilibrium IDS hdf5 files are around
summary: 0.16Mb
equilibrium: 20Mb

Repeating same exercise with both backend, using equiliibrium (I couldn't get mds backend to work via UDA)

yildiz@spcimas: ~  $ IMAS_LOCAL_HOSTS="localhost" ./uda.py -u 'imas://localhost:56565/uda?path=/tmp/yildiz/imasdb/tcv/3/71222/999/&backend=hdf5' -c equilibrium  2>/dev/null |grep "get ="
        get =  8.013
yildiz@spcimas: ~  $ ./uda.py -u 'imas://localhost:56565/uda?path=/tmp/yildiz/imasdb/tcv/3/71222/999/&backend=hdf5' -c equilibrium  2>/dev/null |grep "get ="
        get = 33.998
       
yildiz@spcimas: ~  $ IMAS_LOCAL_HOSTS="localhost" ./uda.py -u 'imas://localhost:56565/uda?path=/tmp/yildiz/imasdb/tcv/3/71222/999/&backend=mdsplus' -c equilibrium   2>/dev/null |grep "get ="
        get =  9.584