Re: [tracecompass-dev] Performance of CPU usage analyses with many threa

[Genevieve Bastien <gbastien+lttng@xxxxxxxxxxxx>]

Hi Rudolf,


There was no benchmark for the CPU Usage analysis, so I made one that queries the backend. For manyThreads, it takes 2.15 minutes to query 10 times the tree on the left and the CPU usage for all threads. There was an easy performance fix, got that down to 1.5 minutes for 10x the full queries (so ~9s for one query of both tree and graph data). So the problem is definitely not the backend (the algorithm is not linear).

After doing some more profiling according to your comments, one would think that if the checkboxes are not visible, they would not be rendered, but that is apparently not true, it is still checking the checked state of each box, no matter if it's visible or not. And that still takes forever. Somebody in the team is looking into this. Hopefully we'll "fix" that pretty soon.


Thanks and don't hesitate if you notice any other such performance hit!

Regards,

Geneviève


On 2019-02-21 4:36 a.m., rreinsberger@xxxxxxxxx wrote:
> Hello Geneviève,
>
> I tried the same with a collapsed tree so that only the topmost check box remains. So, selecting this one implicitly selects all 1535 collapsed threads. Although there is nothing apparently to render in this case (in terms of individual thread checkboxes) the result is the same as with the expanded tree view.
>
> However, trying to render just individual threads from this example takes between 5s to 7s on my machine (which is well aged but with an i7 core after all). That would roughly mean about 2 hours to render all 1535 threads. So, I am not that sure that it's definitely the GUI check boxes causing this run time?
>
> As the many-threads example I use is from the test repository do you know if there is any test protocol for this test case telling about the expected results and run time?
>
> Regards,
> Rudolf
>
>
>
> Am 2019-02-18 16:44, schrieb Genevieve Bastien:
>> Hi Rudolf,
>>
>> Wow, reading this bug report brings back memories... Claudette nodes...
>>
>> Anyway, indeed, on the backend side, there should be no performance
>> problems anymore, and from doing a bit of sampling after reading your
>> mail, the performance problem you're experience comes from the
>> frontend: The UI spends most of its time rendering checkboxes of the
>> tree items... Because there's a lot of items in this tree, yet only a
>> few of them are visible. I think the 'tree' widget of those views
>> should be more lazy and display only the visible items instead of all
>> of them. There should be a bug for that. Especially that we have more
>> and more of that type of views with a lot of items...
>>
>> Thanks for bringing this up,
>>
>> Regards,
>>
>> Geneviève
>>
>>
>> On 2019-02-18 8:05 a.m., rreinsberger@xxxxxxxxx wrote:
>>> Hello,
>>>
>>> Evaluating the CPU usage analyses and view I used sample/test data from here:
>>>
>>> https://github.com/tracecompass/tracecompass-test-traces/tree/master/ctf/src/main/resources/many-threads
>>>
>>> … and from here (see file attachment in the report):
>>>
>>> https://bugs.eclipse.org/bugs/show_bug.cgi?id=460261
>>>
>>> Trying to update the CPU usage graph with all threads selected the analyses took a very long time (>30 min) until Trace Compass (v4.2) was eventually rendered unresponsive.
>>>
>>> It seems that in the bug report referred to above this problem (or at least parts of it) were addressed. However, I am not sure what performance and results are to be expected for this test traces. Is the CPU usage supposed to work and produce results with this trace data in TC version 4.2?
>>>
>>> Regards,
>>> Rudolf
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