Set Performance Objectives

Your project goals must include measurable performance objectives. From the very beginning, design so that you are likely to meet those objectives. Do not over-research your design. Use the planning phase to manage project risk to the right level for your project. To accomplish this, you might ask the following questions: How fast does your application need to run? At what point does the performance of your application become unacceptable? How much CPU or memory can your application consume? Your answers to these questions are your performance objectives. They help you create a baseline for your application’s performance. These questions help you determine if the application is quick enough.

Performance objectives are usually specified in terms of the following:
Response time. Response time is the amount of time that it takes for a server to respond to a request.
Throughput. Throughput is the number of requests that can be served by your application per unit time. Throughput is frequently measured as requests or logical transactions per second.
Resource utilization. Resource utilization is the measure of how much server and network resources are consumed by your application. Resources include CPU, memory, disk I/O, and network I/O.
Workload. Workload includes the total number of users and concurrent active users, data volumes, and transaction volumes.

You can identify resource costs on a per-scenario basis. Scenarios might include browsing a product catalog, adding items to a shopping cart, or placing an order. You can measure resource costs for a certain user load, or you can average resource costs when you test the application by using a certain workload profile. A workload profile consists of a representative mix of clients performing various operations.

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Performance Modeling

Performance modeling helps you evaluate your design decisions against your objectives early on,before committing time and resources. Invalid design assumptions and poor design practices may mean that your application can never achieve its performance objectives. The performance modeling process model presented in this guide is summarized in Figure.

Eight-step performance modeling process

Eight-step performance modeling process

The performance modeling process consists of the following steps:
1. Identify key scenarios. Identify those scenarios in which performance is important and the ones that pose the most risk to your performance objectives.
2. Identify workloads. Identify how many users, and how many concurrent users, your system needs to support.
3. Identify performance objectives. Define performance objectives for each of your key scenarios. Performance objectives reflect business requirements.
4. Identify budget. Identify your budget or constraints. This includes the maximum execution time in which an operation must be completed and resource utilization such as CPU, memory, disk I/O, and network I/O constraints.
5. Identify processing steps. Break your scenarios down into component processing steps.
6. Allocate budget. Spread your budget determined in Step 4 across your processing steps determined in Step 5 to meet the performance objectives you defined in Step 3.
7. Evaluate. Evaluate your design against objectives and budget. You may need to modify design or spread your response time and resource utilization budget differently to meet your performance objectives.
8. Validate. Validate your model and estimates. This is an ongoing activity and includes prototyping, testing, and measuring.

XML serialization is slower than Binary

First, and likely foremost, the data produced from XML serialization is significantly larger than that from the binary serializer
Second: XmlSerializer uses reflection to access the public properties on your types. Your properties might not be simple get/set. In contrast, the BinaryFormatter looks directly at fields, so you are not affected by any less-than-efficient properties you might be serializing.
Note that both the XmlSerializer and BinaryFormatter provide a mechanism whereby you – as the author of the serialized types – can control serialization. See IXmlSerializable and ISerializable. AFAIK, only BinaryFormatter allows you to customize serialization when you’re not the author of the types being serialized (see ISerializationSurrogate).

Actually it is the BinaryFormatter that uses reflection and XmlSerializer generates code to Serialize and Deserialize and hence getting and setting values is actually faster in XmlSerializer (unless your property getter and setter does non trivial tasks)

 

However BinaryFormatter is usually found to be faster in cases where the serialized data is predominantly numeric (array of ints etc.) This is due to the fact that the XmlSerializer has to convert the data to/from string. XmlSerializer is also found to be slower than BinaryFormatter in cases where the objects are deeply nested (e.g. A contains B, B contains C, C contains D and so on)

 

XmlSerializer is significantly slower the first time since it works by generating helper classes to serialize and deserialize and the generated serializer has to be compiled. The subsequent invocation should be fast. To avoid the first time slow down one can use sgen.exe. You can find more information about this at http://msdn2.microsoft.com/en-us/library/bk3w6240(vs.80).aspx

 

If performance is the main reason for choosing the serialization technology then I strongly suggest you to look at the DataContractSerializer that ships in .NET 3.0 (as part of WCF). When used with the binary XML (also shipped as part of WCF) the DataContractSerializer outperforms both serializers in most of the scenarios. You can find more information about the DataContractSerializer at http://msdn2.microsoft.com/en-us/library/system.runtime.serialization.datacontractserializer.aspx. You can find info about the Binary XML at http://blogs.msdn.com/drnick/archive/2007/04/09/what-a-binary-encoding-means.aspx and http://www.wintellect.com/cs/blogs/jsmith/archive/2006/03/28/wcf-xmldictionaries.aspx

WCF Serialization Programming Model

DataContract is the default serialization programming model for WCF. However WCF supports more than just the types marked wth DataContract attribute. It supports serialization of the following kinds of types in the default mode.

CLR built-in types
Byte array, DateTime, TimeSpan, GUID, Uri, XmlQualifiedName, XmlElement and XmlNode array
Enums
Types marked with DataContract or CollectionDataContract attribute
Types that implement IXmlSerializable
Arrays and Collection classes including List<T>, Dictionary<K,V> and Hashtable.
Types marked with Serializable attribute including those that implement ISerializable.
Some types may implement more than one of the above programming model. In such cases a programming model is chosen based on its priority as given by the above list. For example, Hashtable is a collection class but also implements ISerializable and it is serialized as a collection type. DataSet implements both IXmlSerializable and ISerializable and it is serialized as IXmlSerializable.

(sursa: http://blogs.msdn.com/sowmy/archive/2006/02/22/536747.aspx)

Performance Counters for ASP.NET

ASP.NET System Performance Counters
ASP.NET supports the ASP.NET system performance counters listed in the following table. These counters aggregate information from all ASP.NET applications on a Web server computer.

Note:
There is a significant difference between the State Server Sessions counters found in the ASP.NET performance object, which apply only to the server computer on which the state server is running, and the Sessions counters found in the ASP.NET Applications performance object, which apply only to user sessions that occur in-process.

Application Restarts
The number of times that an application has been restarted during the Web server’s lifetime. Application restarts are incremented each time an Application_OnEnd event is raised. An application restart can occur because of changes to the Web.config file, changes to assemblies stored in the application’s Bin directory, or when an application must be recompiled due to numerous changes in ASP.NET Web pages. Unexpected increases in this counter can mean that problems are causing your Web application to recycle. In such circumstances you should investigate as soon as possible.

Note:
This value is reset to zero every time the Internet Information Services (IIS) host is restarted.

Application Running
The number of applications running concurrently on the server computer.

Requests Disconnected
The number of requests that have been disconnected due to a communication failure.

Requests Queued
The number of requests waiting for service from the queue. When this number starts to increment linearly with increased client load, the Web server computer has reached the limit of concurrent requests that it can process. The default maximum for this counter is 5,000. You can change this setting in the Machine.config file.

Requests Rejected
The total number of requests not executed because of insufficient server resources to process them. This counter represents the number of requests that return a 503 HTTP status code, indicating that the server is too busy.

Request Wait Time
The number of milliseconds that the most recent request waited in the queue for processing.

Session State Server Connections Total
The total number of session-state connections made to the computer on which out-of-process session-state data is stored. For more information, see Session-State Modes.

Session SQL Server Connections Total
The total number of session-state connections made to the Microsoft SQL Server database in which session-state data is stored. For more information, see Session-State Modes.

State Server Sessions Abandoned
The number of user sessions that have been explicitly abandoned. These are sessions that are ended by specific user actions, such as closing the browser or navigating to another site. This counter is available only on the computer where the state server service (aspnet_state) is running.

State Server Sessions Active
The number of currently active user sessions. This counter is available only on the computer where the state server service (aspnet_state) is running.

State Server Sessions Timed Out
The number of user sessions that have become inactive through user inaction. This counter is available only on the computer where the state server service (aspnet_state) is running.

State Server Sessions Total
The number of sessions created during the lifetime of the process. This counter is the total value of State Server Sessions Active, State Server Sessions Abandoned, and State Server Sessions Timed Out. This counter is available only on the computer where the state server service (aspnet_state) is running.

Worker Process Restarts
The number of times a worker process has been restarted on the server computer. A worker process can be restarted if it fails unexpectedly or when it is intentionally recycled. If this counter increases unexpectedly, you should investigate as soon as possible.

Worker Process Running
The number of worker processes running on the server computer.

ASP.NET Application Performance Counters
ASP.NET supports the application performance counters listed in the following table. These counters enable you to monitor the performance of a single instance of an ASP.NET application. A unique instance named __Total__ is available for these counters. This instance aggregates counters for all applications on a Web server (similar to the global counters described earlier in this topic). The __Total__ instance is always available. The counters will display zero when no applications are currently executing on the server.

Anonymous Requests
The number of requests that are using anonymous authentication.

Anonymous Requests/Sec
The number of requests per second that are using anonymous authentication.

Cache Total Entries
The total number of entries in the cache. This counter includes both use of the cache by the ASP.NET page framework and use of the application cache through cache APIs.

Cache Total Hits
The total number of hits from the cache. This counter includes both use of the cache by the ASP.NET page framework and use of the application cache through cache APIs.

Cache Total Misses
The number of failed cache requests per application. This counter includes both use of the cache by the ASP.NET page framework and use of the application cache through cache APIs.

Cache Total Hit Ratio
The ratio of hits to misses for the cache. This counter includes both use of the cache by the ASP.NET page framework NET and use of the application cache through cache APIs.

Cache Total Turnover Rate
The number of additions and removals to the cache per second, which is useful in helping to determine how effectively the cache is being used. If the turnover rate is high, the cache is not being used efficiently.

Cache API Entries
The total number of entries in the application cache.

Cache API Hits
The total number of hits from the cache when it is accessed only through the external cache APIs. This counter does not track use of the cache by the ASP.NET page framework.

Cache API Misses
The total number of failed requests to the cache when accessed through the external cache APIs. This counter does not track use of the cache by the ASP.NET page framework.

Cache API Hit Ratio
The cache hit-to-miss ratio when accessed through the external cache APIs. This counter does not track use of the cache by the ASP.NET page framework.

Cache API Turnover Rate
The number of additions and removals to the cache per second when used through the external APIs (excluding use by the ASP.NET page framework). It is useful in helping determine how effectively the cache is being used. If the turnover rate is high, then the cache is not being used effectively.

Compilations Total
The total number of compilations that have taken place during the lifetime of the current Web server process. Compilation occurs when a file with an .aspx, .asmx, .ascx, or .ashx file name extension, or a code-behind source file, is dynamically compiled on the server.

This number will initially climb to a peak value as requests are made to all parts of an application. Once compilation occurs, however, the resulting compiled output is saved to disk, where it is reused until its source file changes. This means that even in the event of a process restart the counter can remain at zero (inactive) until the application is modified or redeployed.

Debugging Requests
The number of requests that occur while debugging is enabled.

Errors During Preprocessing
The number of errors that occurred during parsing, excluding compilation and run-time errors.

Errors During Compilation
The number of errors that occur during dynamic compilation, excluding parser and run-time errors.

Errors During Execution
The total number of errors that occur during the execution of an HTTP request, excluding parser and compilation errors.

Errors Unhandled During Execution
The total number of unhandled errors that occur during the execution of HTTP requests. An unhandled error is any run-time exception that is not trapped in user code and enters the ASP.NET internal error-handling logic. Exceptions to this rule occur when:

Custom errors are enabled, an error page is defined, or both.

The Page_Error event is defined in user code and either the error is cleared (using the ClearError method) or a redirect is performed.

Errors Unhandled During Execution/Sec
The number of unhandled exceptions per second that occur during the execution of HTTP requests.

Errors Total
The total number of errors that occur during the execution of HTTP requests, including any parser, compilation, or run-time errors. This counter is the sum of the Errors During Compilation, Errors During Preprocessing, and Errors During Execution counters. A well-functioning Web server should not generate errors. If errors occur in your ASP.NET Web application, they may skew any throughput results because of very different code paths for error recovery. Investigate and fix any bugs in your application before performance testing.

Errors Total/Sec
The number of errors per second that occur during the execution of HTTP requests, including any parser, compilation, or run-time errors.

Output Cache Entries
The total number of entries in the output cache.

Output Cache Hits
The total number of requests serviced from the output cache.

Output Cache Misses
The number of failed output-cache requests per application.

Output Cache Hit Ratio
The percentage of total requests serviced from the output cache.

Output Cache Turnover Rate
The number of additions and removals to the output cache per second. If the turnover rate is high, the cache is not being used effectively.

Pipeline Instance Count
The number of active request pipeline instances for the specified ASP.NET application. Since only one execution thread can run within a pipeline instance, this number gives the maximum number of concurrent requests that are being processed for a given application. In most circumstances it is better for this number to be low when under load, which signifies that the CPU is well utilized.

Request Bytes In Total
The total size in bytes of all requests.

Request Bytes Out Total
The total size in bytes of responses sent to a client. This does not include HTTP response headers.

Requests Executing
The number of requests currently executing.

Requests Failed
The total number of failed requests. Any status codes greater than or equal to 400 will increment this counter.

Requests that cause a 401 status code increment this counter and the Requests Not Authorized counter. Requests that cause a 404 or 414 status code increment this counter and the Requests Not Found counter. Requests that cause a 500 status code increment this counter and the Requests Timed Out counter.

Requests Not Found
The number of requests that failed because resources were not found (status code 404 or 414).

Requests Not Authorized
The number of requests that failed due to no authorization (status code 401).

Requests Succeeded
The number of requests that executed successfully (status code 200).

Requests Timed Out
The number of requests that timed out (status code 500).

Requests Total
The total number of requests since the service was started.

Requests/Sec
The number of requests executed per second. This represents the current throughput of the application. Under constant load, this number should remain within a certain range, barring other server work (such as garbage collection, cache cleanup thread, external server tools, and so on).

Sessions Active
The number of sessions currently active. This counter is supported only with in-memory session state.

Sessions Abandoned
The number of sessions that have been explicitly abandoned. This counter is supported only with in-memory session state.

Sessions Timed Out
The number of sessions that timed out. This counter is supported only with in-memory session state.

Sessions Total
The total number of sessions. This counter is supported only with in-memory session state.

Transactions Aborted
The number of transactions canceled for all active ASP.NET applications.

Transactions Committed
The number of transactions committed for all active ASP.NET applications.

Transactions Pending
The number of transactions in progress for all active ASP.NET applications.

Transactions Total
The total number of transactions for all active ASP.NET applications.

Transactions/Sec
The number of transactions started per second for all active ASP.NET applications.

(sursa: http://msdn.microsoft.com/en-us/library/fxk122b4.aspx)