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Graphs for Individual Pages
Graphs for Individual Pages
WAPT creates
graphs for all page requests of the current test scenario.
You can view graphs on test completion to know how tests were performed.
You can also view intermediate results at run-time while your test is being executed.
Click on any page in the Results folder of the Navigation Pane to see the chart.
There are 3 tabs on the chart:
You can manually choose what graphs will be shown on the chart. Check/uncheck options below the
chart to show/hide graphs. You can check the All option to display all graphs on this tab.
Tip:
Note that Y axis on the chart is different for various graphs. For example: : The number of active users
is displayed on the right side of the chart. : Values of
minimum response time are displayed on the left side of the chart.
X axis denotes the time interval of test run.
The whole time interval is divided into a number of intervals, each of them equal to the
Refresh time value specified in Log and Report Settings.
If you place the mouse cursor over
a graph node, the value in the current node will pop up. If you cannot see the whole graph
at once, you can drag it with the mouse to view all its parts. You can increase/decrease the scale
of any axis on the chart. Place the mouse cursor over axis values and drag them to get desired scale.
Autofit chart
You can use the Autofit chart option to scale the graph down to window size.
Double-clicking on the chart will have the same result.
Resample
If there are too many nodes displayed on the chart and neighbour nodes merge together,
you can resample the graph with the Resample arrow.
Timings tab
All timing values on this tab are displayed in seconds.
Response time tells you how long a user waits for
server response to his request. The values of average and maximum response time are the most
important results of load testing; they measure web user experience.
You should watch how these
values change during a test when the number of virtual users is increasing, and verify that
users get the response in acceptable time.
There are 3 important limits for response time values:
0.1 second.
It is an ideal response time. Users feel that the system is reacting instantaneously, and don't
sense any interruption. 1.0 second.
It is the highest acceptable response time. Users still don't feel an interruption, though they
will notice the delay. Response times above 1 second interrupt user experience. 10 seconds.
It is the limit after which response time becomes unacceptable. Moreover, recent studies show
that if response time exceeds 8 seconds, user experience is interrupted very much and most
users will leave the site or system.
Normally, response times should be as fast as possible. The interval of most comfortable
response times is 0.1 - 1 second. Although people can adapt to slower response times, they are
generally dissatisfied with the times longer than 2 seconds.
Below are 3 possible variants of Response time graph behavior when the number of users is
increasing:
Flat (or very slight growth): It is an ideal result. The increase of load on the
server doesn't lead to the increase of response time (or leads to very slight growth).
Gradual growth (essential growth): The increase of load on the server leads to
gradual growth of response time. It means that the server can handle the growing level of load
until the load exceeds some maximum value. Possible reasons of such situation are problems
with the server hardware, for example, insufficient network bandwidth or low productivity of the
server.
Sharp growth: If the response time graph exhibits a sharp growth beginning from some
level of user load while the download time graph doesn't grow essentially, it means that the server
provides a poor performance when the load reaches this level, or even cannot cope with such
load. Users will see that the server responds very slowly, or doesn't respond at all.
Graphs described in first two cases - flat or gradually growing - can suddenly exhibit a sharp
growth. A point where the graph begins to grow sharply is called a performance breakpoint. After
this breakpoint, server performance degrades noticeably.
Note that you may use such interpretation of the response time graph only if the download time graph
doesn't exhibit an essential growth. If the percentage of download time from the response time is
rather high, it indicates that there are problems with the connection bandwidth, but not with
server performance.
Min response time: Shows values of minimum response time for the current page request.
This time doesn't include the time for loading the images;
it is the time of server response to the readable content of web page:
its structure (frames, tables) and HTML text. These elements are sufficient to start reading
a page.
Min response + images time: Shows the minimum response time
of server response to web page with all its elements including images and flash movies.
First of all, you need to analyze the response time without images as it is the time after which
users can start reading a page. Response time including images will help you ensure that users
won't have problems with the download of graphic images and flash movies located on the current page.
Avg response time: Shows values of average response time
without images.
Avg 90% response time: Shows values of average response time without images
calculated for 90% of all participated users.
Avg response + images time: Shows values of average response time
including the time for loading the images.
Avg 90% response + images time: Shows values of average response time including images
calculated for 90% of all participated users.
Avg download time: Shows values of average download time for the current page request.
WAPT measures
download time without images.
It is the time from the moment a user sees a web page title (in browser's title bar) till the
moment he can start reading a page, i.e. when readable content of web page is displayed on
user's monitor.
Download time is the measure of web server connection bandwidth. It indicates whether the
bandwidth is sufficient to provide a required level of performance or not. If the growth of
virtual users number leads to the rapid increase of download time, then most probably your server
connection bandwidth is inadequate.
On the whole, you should watch response and download times together. If download time is the
major part of response time value, it means that you have problems with the connection bandwidth.
You should also analyze other results related to bandwidth: the speed of receiving the
information from the server and speed of sending the information to the server.
If Download time graph exhibits sharp fluctuations, you should provide more stable
test environment: make your test machine as close as possible to the production server,
and conduct tests at off-hours when network traffic is lower.
Avg 90% download time: Shows values of average download time
calculated for 90% of all participated users.
Max response time: Shows values of maximum response time without
images.
Max response + images time: Shows values of maximum response time
including the time for loading the images.
Active users: Shows the number of virtual users who requested this page.
All: Displays all graphs on this tab.
Errors tab Total errors %: Shows the percentage of responses with errors (HTTP errors,
socket errors and timeouts) from the total number of responses to this page.
HTTP errors %: Shows the percentage of responses with HTTP errors
from the total number of responses to this page.
If you receive an HTTP error, it means that there are problems with the work of web server.
Socket errors %: Shows the percentage of responses with socket errors
from the total number of responses to this page.
Socket error means a bad connectivity; it indicates that there are problems with the data transfer through
the socket.
Timeouts %: Shows the percentage of responses with timeouts
(response timeouts and
socket timeouts)
from the total number of responses to this page.
These graphs will help you know how error rate changes during a test when the number of virtual
users is increasing.
Error rate is the most valuable result of stress testing where you need to find the maximum
number of users that can be served correctly, without errors.
You will also need to watch error rate during
reliability/endurance tests to verify that it is in acceptable range even after a long run.
Active users: Shows the number of virtual users who requested this page.
All: Displays all graphs on this tab.
Custom tab Custom tab represents all graphs from the previous tabs and also some more graphs:
Pages per second: Shows the speed of the current page execution averaged for all users
who requested this page.
Hits per second: Shows how many hits were executed per time scale unit for the current page.
These values are measured using the time scale unit (second, minute or hour),
which is specified in Log and Report Settings
(Time scale units combo-box).
Note that a hit is a single request for resource (page code, image, script and so on) sent to the
server, while each page may include many hits. In particular, if "Show pictures" checkbox in advanced
Internet Explorer options is turned off, then the number of hits is equal to the number of pages.
Received: Shows how many kbits per second were received from the server.
Sent: Shows how many kbits per second were sent to the server.
These graphs will help you know whether the bandwidth of Internet connection to your server is
sufficient to provide an acceptable level of performance or not.
Saving Graphs for Individual Pages
You can save any chart as an image in png format in required location. For this,
select a desired tab (Timings, Errors or Custom), right-click on the chart and select the
Save Current Chart to Image... option on the context menu. In the displayed dialog,
enter file name, select a location and click Save.
You will be able to view the chart
later, any time you wish just from Internet Explorer or any other program that supports
png format.
It is also a convenient way to transfer test results to any interested person.
Products
: The number of active users
is displayed on the right side of the chart.
: Values of
minimum response time are displayed on the left side of the chart.
