Performance Testing, LoadRunner Tips & Tricks This page is dedicated to performance testing using LoadRunner. Current development also includes tuning on various technologies and business perspective in load testing and usage of other load testing tools. Statistics Unique Visitors: Total Unique Visitors: Outgoing: Total Outgoing: 0 0 27 3088

Articles from Performance Testing, LoadRunner Tips & Tricks

LoadRunner TnT 2007-10-29 08:57:00 Just to bring to your attention that if you had not subscribed to the contents of my new site, now is the time to do so. I'm still using FeedBurner to deliver quality LoadRunner and Performance Testing content to you. I'm also including information to analyze, troubleshoot and tune whenever I have anything to share with you guys out there. So why wait any further if you are new to this field, take the opportunity to subscribe to the new site now! :) It's free anyway. :)Enter your email address:Delivered by FeedBurner ...

It's a brand new start for LoadRunner TnT 2007-09-06 06:58:00 Many thanks to all who had been following and supporting this website. The time to move to a bigger space has come and we are excited to announce the new website LoadRunner TnT is up and running.Log on to LoadRunner TnT now!The new site will continue to provide quality information on LoadRunner and Performance Testing to help newbies or mid-career performance tester in their work. Posting on this site will be discontinued but for those existing articles, they will be moved to the new home not shortly but surely. ...

General: Load Testing Objectives 2007-08-26 20:40:00 There are two approaches from the user perspective on defining load testing objectives, either top-down (business perspective) or bottom-up (techincal perspective). The top-down, meaning the transaction time take to submit a request and having it responded on the user's machine. This is a business perspective where they just want to know how the application is responding. The user do not want to know how many Hits/sec or Throughput but just want to know how much time was taken for a transaction (therefore the terminology of "transcation" must be aligned with you and the user). The bottom-up, is a techincal perspective as you had pointed out such as the ASP.NET transactions or the database transactions (or commits). This is usually a persepctive from a technical manager so they can configure the system accordingly (or whatever they are going to do their system).Hopefully the above is helpful in understandin your users/clients a little bit more before giving them a satisfying answer.Ge ...

Scripts: Parameterization 2007-08-21 07:14:00 Point to note that parameterization may result in data dependency which the tester should be aware of and handle it appropriately. Every load test should at least require parameterization. Parameterization includes passing different types of data into the application to emulate the real world users performing/entering different values. What do clients want to achieve from parameterization? To test different data Just to load/emulate the data Parameterization requires identifying with the clients which areas required data input. This will be useful when discussing in the Application Design. From there, they can prepare the data from the database which is a more efficient method. Preparing the data Usually after walking through the application, I will request the client to prepare the date via the database and export it out as an excel file. This will reduce the time in preparing lengthy excel or notepad files. From there, you can manipulate the data eas ...

Scripts: Any compatibility issues after upgrading LoadRunner versions? 2007-08-19 00:20:00 Personally, I encountered problem while porting the scripts recorded in 8.0 to 8.1 . This was actually pertaining to Citrix protocol where there is an additional parameter needed for the APIs. This will be particular to users that are using scripts in BPM (Business Process Management) of BAC (Business Availability Center). Take note that BPM uses the same recording tool, VuGen in LoadRunner, however at a version lower than the currently released LoadRunner Vugen).If I didn't recall wrongly, the Citrix API ctrx_sync_on_bitmap, had an additional parameter, "CTRX_LAST" at the end of its parameter list in 8.1 as compared to 8.0. Since then, I haven't had any problem with other protocol scripts so far.Anyway, my advice are as the followed:Read the upgrade readme file.Clone an image prior the upgrade. In this way, you can revert back to the older version.Test the previously recorded scripts from the older version.Do you have any incompatibility issues of scripts before? Feel free to ...

Understanding Network: Performance Measurements 2007-08-15 00:05:00 Evaluating path performance means doing three types of measurements. measurements will give you an idea of the hardware capabilities of your network, such as the maximum capacity of your network. BandwidthThroughput measurements will help you discover what capacity your network provides in practice, i.e., how much of the maximum is actually available. Traffic measurements will give you an idea of how the capacity is being used. Performance Measurements Two factors determine how long it takes to send a packet or frame across a single link. The amount of time it takes to put the signal onto the cable is known as the transmission time or transmission delay. This will depend on the transmission rate (or interface speed) and the size of the frame. The amount of time it takes for the signal to travel across the cable is known as the propagations time or propagations delay. Propagation time is determined by the type of media used and the distance involved. Once we ...

Understanding Network: How traceroute works? 2007-08-12 08:51:00 The program was written by Van Jacobson and others. It is based on a clever use of the Time-To-Live (TTL) field in the IP packet’s header. The TTL field is used to limit the life of a packet. When a router fails or is mis-configured, a routing loop or circular path may result. The TTL field prevents packets from remaining on a network indefinitely should such a routing loop occurs. A packet’s TTL field is decremented each time the packet crosses a router on its way through a network. When its value reaches 0, the packet is discarded rather forwarded. When discarded, the ICMP TIME_EXCEEDED message is sent back to the packet’s source to inform the source that the packet was discarded. By manipulating the TTL field original packet, the program traceroute uses information from these ICMP messages to discover paths through a network. Traceroute sends a series of UDP packets with the destination address of the device you want a path to. * By default, traceroute sends sets of ...

Understanding Network: How Ping Works? 2007-08-08 22:28:00 One network device sends a request for a reply to another device and records the time the request was sent. The device receiving the request sends a packet back. When the reply is received, the round-trip time for packet propagation can be calculated. The receipt of a reply indicates a working connection. This elapsed time provides an indication of the length of the path. Consistency among repeated queries gives an indication of the quality of the connection. Thus, ping answers the two basic questions. Do I have a connection? How good is that connection? Clearly, for the program to work, the networking protocol must support this query/response mechanism. The ping program is based on Internet Control Message Protocol (ICMP), part of the TCP/IP protocol. ICMP was designed to pass information about network performance between network devices and exchange error messages. It supports a wide variety of message types, including query/response mechanism. The normal operation o ...

General: Planning for Load Testing - Recommendations 2007-08-06 20:58:00 After identifying trends, it’s time to propose an action plan, proposal or recommendation to your client. This maybe just telling the client that “Dear client, your application is running at this rate, I would recommend to re-look the SLAs with your users.” or “Dear client, the server housing the application is encountering processor contention. I would like to recommend you to distribute the load across with a new server (or processor).” This is of course tied to the initial requirements and the limitations the clients are bounded in. At this point if they have follow up actions to improve the system, do keep a record of the last changed parameter on the server. This will be useful for you to track the changes over time on their application and determined if the changed had enhanced the application. Unless you are part of the server team, you might not be involved in the tuning process. Once the changes have been made, conduct a load test to verify the changes ...

General: Planning for Load Testing - Analyzing 2007-08-04 23:37:00 This is the stage where it intertwined with the monitoring. At this stage, similarly to Monitoring, it is important to have a sound knowledge of the server or database internal workings. With that you will know what to further investigate and what the graph represents. A graph looks great with the lines flying up and down but that is information. You will need to have a lot of experience to translate that information to useful knowledge. This will be done with merging and correlating of the load generated against the utilization of resources. You must be able to “see” the trend and identify possible bottlenecks.I would recommend acquiring lots of information of the server (either the software or hardware perspective) you are monitoring as this is required for your analyzing. You can refer a previous consolidated article, "Content Page - General" which provides a proportion of basic information that will be useful to you in facilitating the analyzing.Other than the knowledg ...

General: Planning for Load Testing - Monitoring 2007-08-02 21:01:00 I separated the Monitoring from the Monitor Setup because I feel that the setup is prior the load test runs. In this stage, what we are concerned are the counters and metrics to monitor. If you are starting off without any knowledge or history of the system such as performance issues, it’s advisable to monitor the 4 main categories, namely Processor, Memory, Disk and Network. Once the load test completes, you should have an overview of the application performance. From there, go to a 2nd level of monitoring till the nth level until you are satisfied with the investigation.For example, on the 1st load test, you observed that the page faults are occurring at a level higher than the accepted threshold indicating memory problems. From there, you may want to investigate further on the cause of the page fault such as, if it is a hard page fault or soft page fault. Therefore, you may like to monitor the Transition Faults, Pages Input and Pages Output to answer your doubts. Of course, ...

Monitors: Memory Glossary 2007-08-01 00:33:00 This is a compilation of memory-related counters. Do feel free to revert or comment should you have additional information on the counter.Available BytesProcess Working Set growth becomes constrained when Available Bytes Pool Nonpaged BytesThe system’s non-pageable (fixed) memory.Pool Paged Resident BytesThe OS‘s pageable memory that is currently resident in RAM.System Code Resident Bytes[Coming soon]System Driver Resident BytesTotal System Resident Bytes = Pool Nonpaged Bytes + Pool Paged Resident Bytes + System Code Resident Bytes + System Driver Resident Bytes + System Cache Resident Bytes.System Cache Resident BytesThe current amount of RAM used for the file cache.Page Faults/secCan be a grossly misleading number. Page Faults/sec = “soft” Transition Faults + application file Cache Faults + demand zero faults + hard page faults.Page Reads/secThis counter measures the number of requests to the I/O manager to retrieve pages of memory from the disk. Despite the name of this c ...

General: Planning for Load Testing - Monitor Setup 2007-07-30 09:25:00 The setting up of monitors poses some challenge and I advised you to cater one or two days to implement the monitors. LoadRunner features agentless monitoring (which other products do too). However, in order to achieve such feature it needs the SUT (System Under Test) to be configured properly. This “configure properly” becomes sort of “out-sourced” to the system admin team and if problem arises, the blame of product issue will be reduced. Depending on the type of monitors you are implementing, you will require time and effort to clear ports and justify your case to the security or the network team before the actual implementation is possible. This is where the initial gathering of information is important in Soliciting Requirements. With the architecture diagram, you can relate to the security or network team on the team of installation of agents or opening of ports. But of course this will come under scrutiny if you do not provide sufficient convincing informa ...

General: Planning for Load Testing - Protocols 2007-07-24 21:04:00 Load testing is about capturing the traffic sent by the application to the server. And using the captured traffic, the tool scripts out APIs to generate the traffic, which is been emulated during replay and sent back to the server. Through understanding the Application Design, you should be able to determine the type of protocol that is been communicated. As I pointed in previous articles , LoadRunner focuses a lot on protocol and therefore the need to know this information is critical. To be able to read the logs and find meaningful information out of it, I would recommend you to acquire as much knowledge as possible. For example, HTTP, the replay log merely displays the transmission of the HTTP requests in text. From there, you will know information such as authentication headers or the body that was sent. I cannot emphasize again that do not associate functional testing as load testing. Therefore, if you are from the functional testing background, please be sure to acquire more know ...

Understanding Memory: Virtual Addressing (Illustration) 2007-07-22 20:26:00 The following illustration explains the process of virtual addressing when a program is loaded into memory. For detailed explanation, refer to "Understanding Memory: Virtual Addressing".Executable program image file loads into memory.Logical memory address range of the application is divided into fixed-size chunks caled pages.Page mapping in Virtual Memory is dynamic.Frequently referenced logical addresses tend to reside in physical memory.Infrequently referenced pages are relegated to paging files on secondary disk storage.Related TopicsContent Page - General Virtual AddressingPage Fault Resolution Page Fault Resolution (Illustration) Performance Concerns Virtual Memory Shortage Alerts Available Bytes LRU System Working Set Detecting Memory Leaks Measuring Memory Utilization ...