Acceptable level of page faults

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I have an ASP.NET application, hosted on two web servers. I am looking
for advice on what should be an acceptable level of page faults on
these production servers. If the acceptable level is zero, then where
should I begin reducing page faults in code? What should I look for in
code to reduce page faults?

Having to reduce page faults is something I have not had been tasked
with before, so I am not sure what is acceptable and where to begin.

Thanks,

Alex
 
The acceptable level is zero.

There may be specific things that are environmental and out of your
control (such as dependence on outside web services, network, etc) but
those faults should be handled internally by your app and therefore do
not bleed through to your users as faults.

The place to start is your logs, and if you don't have any then start
logging. There's generally an accepted thought in you should only
catch exceptions if you can do something about that. This is wrong
(IMO). You should catch and rethrow exceptions with additional
information whenever you have additional information to provide (which
is pretty much always--your method parameters, values in relevant
variables, etc). Then once you have logging in place look at the
stack traces and track errors down one by one.

HTH,

Sam
 
Sam,

I appreciate your thoughts. I do have logging in place, using Log4Net,
as well as my own HttpModules I have created to monitor exceptions and
unhandled exceptions. What I am seeing is that I do not have many
errors being logged, but it sounds like it is more than that. Perhaps
Log4Net warnings and any situation where a "catch" is reached in a try/
catch need to be evaluated. If having 1 page fault is too many, than I
need to increase details about any error.

The next question is, how practical is it to reach a level or zero
page faults? I guess there must be a balance between how many
resources I dedicate to reducing page faults, since having page faults
does not appear to impair the application from a user's perspective
that I can tell at this point. I was under the impression that page
faults are a necessary. Even with a basic ASP.NET application with
just one Default.aspx page and no functionality added to the project,
I still get some page faults. I cannot get zero. Just by running
aspnet_wp.exe or w3wp.exe I am averaging 180 page faults/sec,
according to perfmon.

Thanks again,

Alex
 
Sam,

One more thing. When I noticed that my default ASP.NET application is
accruing page faults, this could be erroneous and misleading. Since I
am using Perfmon, Perfmon could be collecting data on page faults
outside of my w3wp.exe or aspnet_wp.exe processes. The OS continually
has page faults. What I did this time was to set up a baseline, where
I start the w3wp or aspnet_wp process and see how many page faults it
accumulates using Task Manager. I then look for a page fault delta to
see how much my application is contributing to this. The hard question
will be determining what levels is acceptable.

Thanks,

Alex
 
You need to be more clear.
What page faults are you talking about.....


Errors on your ASPX pages????? Here acceptable is 0. There should never be
unexplained error. There are a lot of bots going around that look for
emails, faxes, .... they submit form and very often they generate an errors
simply by supplying incorrect data cause they mess with hidden fields as
well (like viewstate for example).

Or system page faults in Task Manager? I would not worry about it and let
OS to manage that. Just add more memory to reduce it if it really slows down
your server.


George
 
Thanks George. The page faults that are being monitored really are
system page faults, or those caused by the application. The app is not
throwing any errors, like unhandled exceptions, and the app pool is
not being recycled as a result of any of these errors. I guess it is
difficult for me to say how these pages faults are being caused by the
web application, if they are or not. Do you recommend any tools to
help me determine if these page faults are because of my ASP.NET
application (code) or if they are being caused by something other than
my code?

Thanks,

Alex
 
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