[Engine-devel] [UX] how to design a bar/line chart?

[Lior Vernia]

Sorry, obviously I meant RAM usage...

On 07/11/13 08:51, Lior Vernia wrote:
> 
> 
> On 06/11/13 16:26, Einav Cohen wrote:
>> Hi Tomas,
>>
>> Like Itamar, I think that a line chart is a better idea, and that a 
>> chart per monitored fact (rather than a combined chart) is better.
>>
>>>> the statistics readable enough. Maybe if you hover the chart it could pop
>>>> up a bigger version of the chart? Or not needed?
>>
>> this is a nice-to-have, I think, definitely not needed.
>>
>>>> - Would it be enough to have it in one color? Or should it be something
>>>> like "the bigger the utilization the more red"?
>>
>> question is what will happen when there are a lot of "jumps": let's say 
>> that the graph changes from 0% to 100% to 0% to 100% and so on... what 
>> will be painted red? the entire line, but only in the periods that it 
>> jumps to 100%? only the parts of line that are in 100%?
>> maybe a single color is enough.
>>
>> I have another concern about this feature: currently, the GUI's most frequent 
>> refresh rate available is 5 seconds, which means that the line will "change" 
>> only every 5 seconds, which would be more noticeably slow when displayed in 
>> a form of a line chart (not even talking about lower frequencies).
>> Moreover, I am not sure at what rate the VM statistics are pulled from VDSM, 
>> but if it is 10 seconds or 15 seconds, it means that the line in the GUI will 
>> be "flat" for every 2 reads / 3 reads, which is not so good, I think.
>>
>> any thoughts around that?
>>
> 
> If this is indeed an issue, it could be easily solved by delaying the
> presentation of the value obtained from VDSM, and at each moment present
> a linear interpolation of the value between the previous input and the
> current input.
> 
> Formally put, let's say T is the measurement period time. If the value
> at time t is f(t), then at time t-T <= t' <= T we would display the
> value f(t-2T) + [f(t-T) - f(t-2T]*t'/T, where we control the increment
> rate of t'.
> 
> For example, let's say we get a new value from VDSM every 15 seconds. 30
> seconds ago the CPU usage was 50MB, 15 seconds ago 100MB and now 200MB.
> We decided to update the graph every 3 seconds.
> 
> 15 seconds ago we displayed 50MB (the value from 30 seconds ago). 12
> seconds ago we displayed 60MB, 9 seconds ago 70MB, 6 seconds ago 80MB, 3
> seconds ago 90MB, and now we display 100MB (which is again late by 15
> seconds). We will only display 200MB in 15 seconds, after increasing our
> displayed value by 20MB every 3 seconds.
> 
>> ----- Original Message -----
>>> From: "Itamar Heim" <iheim at redhat.com>
>>> To: "Tomas Jelinek" <tjelinek at redhat.com>, "engine-devel" <engine-devel at ovirt.org>
>>> Sent: Tuesday, November 5, 2013 10:10:34 AM
>>> Subject: Re: [Engine-devel] [UX] how to design a bar/line chart?
>>>
>>> On 11/05/2013 11:50 AM, Tomas Jelinek wrote:
>>>> Hi all,
>>>>
>>>> There is a feature request [1] which aims to replace the resource
>>>> utilization graphs (for example the cpu utilization from vm tab) by some
>>>> which shows not only
>>>> the actual percentage which is not so useful by some monitor graph.
>>>>
>>>> I have the following concerns:
>>>> - I can think of a bar chart or a line chart and not sure what would be
>>>> better.
>>>> - Not sure if replacing the current chart with a bar/line chart would make
>>>> the statistics readable enough. Maybe if you hover the chart it could pop
>>>> up a bigger version of the chart? Or not needed?
>>>> - Would it be enough to have it in one color? Or should it be something
>>>> like "the bigger the utilization the more red"?
>>>>
>>>> Please advise from the UX perspective. As soon as the final design will be
>>>> a bit more clear I will provide a feature page.
>>>>
>>>> Thank you,
>>>> Tomas
>>>>
>>>> [1]: https://bugzilla.redhat.com/show_bug.cgi?id=803251
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>>>>
>>>
>>> a moving trend graph (just like fedora's system monitor for
>>> cpu/ram/network) is what i have in mind. so a line chart.
>>> you could have a single chart with different lines for cpu/ram/network,
>>> or what seems to be more common, a chart per monitored fact
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>>>
>>>
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