Data Execution Prevention (DEP) in Windows 7 and above

Problem:
Sometimes, VuGen will not record any events while recording the AUT. If you raise a HP ticket for this problem, HP team will ask you to check your DEP settings is disabled.
Now we see how to disable the DEP settings in Windows 7 and above machines.

Steps:
1. Login to Windows with a user account that has administrative privileges.
2. From a DOS command line run the command "> bcdedit.exe"
Confirm the default value for the "nx" parameter. If it is OptIn, then DEP is enabled.

3. Disable DEP by setting the "nx" parameter to "AlwaysOff" using the command "> bcdedit.exe /set nx AlwaysOff"

4. Rerun the command in step 2 above and verify that the "nx" parameter is set to "AlwaysOff".

5. Reboot the system to ensure that the "nx" parameter setting takes effect and DEP is disabled.

GENERAL_MSG_CAT_SSL_ERROR]connect to host "" failed: [10054] Connection reset by peer"

"Error -27780: [GENERAL_MSG_CAT_SSL_ERROR]connect to host "" failed: [10054] Connection reset by peer"

 When you are replaying the script in VuGen, sometime you may get the below error.
"Error -27780: [GENERAL_MSG_CAT_SSL_ERROR]connect to host "" failed: [10054] Connection reset by peer"

Application is using SSL version TLSv1, however while running the script from Loadrunner, by default it is sending SSL version SSL2/3. This is the root cause of the problem

To avoid this error, you can follow either one of the steps mentioned below.

a) Include the below statement at the first line of Vuser_init section.

                web_set_sockets_option("SSL_VERSION","TLS"); 

b) In the recording options, Go to Port Mapping -> Options -> Click on "Enable auto SSL detection" and select SSL version as "TLS 1.x". Then Click on Update and save the changes.

Then regenerate the script with the updated settings.

Little's law

Concurrent Users using Little's law

The below real time example will help in deriving the concurrent users using Little's law. In the below example

• Adjusted Hits, Median Think Time derived from production logs for one hour period.
• Avg RT/Step  is the Target Response SLA required to met under load
• No of Steps is no of transactions per business flow
• Concurrent Users is derived using little's law Throughput* (Avg RT+ Think Time)

Performance Counters - Network

Network Throughput

\Network Interface(*)\Bytes Received/sec

The Network Interface Bytes Received/sec shows the Network Received Throughput of the NIC. This is normally displayed in bytes, but we do the calculation when graphing the counter to display it in the standard MB/sec.

Microsoft® Description - Bytes Received/sec is the rate at which bytes are received over each network adapter, including framing characters. Network Interface\Bytes Received/sec is a subset of Network Interface\Bytes Total/sec.

\Network Interface(*)\Bytes Sent/sec

The Network Interface Bytes Sent/sec shows the Network Send Throughput of the NIC. This is normally displayed in bytes, but we do the calculation when graphing the counter to display it in the standard MB/sec.

Microsoft® Description - Bytes Sent/sec is the rate at which bytes are sent over each network adapter, including framing characters. Network Interface\Bytes Sent/sec is a subset of Network Interface\Bytes Total/sec.

Performance counters - Disk

Disk Throughput

The Disk subsystem could be a major system performance bottleneck, because of this we decided to focus on many disk performance counters and present the information by either graphing the total combined counters from all the Disks in the System or to graph the individual disk counters to allow you to pinpoint issues.

\PhysicalDisk(*)\Disk Read Bytes/sec

The Disk Read Bytes/sec shows the Disk Throughput of the Read Operation of the Disk. This is normally displayed in bytes, but we do the calculation when graphing the counter to display it in the standard MB/sec.

Microsoft® Description - Disk Read Bytes/sec is the rate at which bytes are transferred from the disk during read operations.

\PhysicalDisk(*)\Disk Write Bytes/sec

The Disk Write Bytes/sec shows the Disk Throughput of the Write Operation of the Disk. This is normally displayed in bytes, but we do the calculation when graphing the counter to display it in the standard MB/sec.

Microsoft® Description - Disk Write Bytes/sec is rate at which bytes are transferred to the disk during write operations.

Disk Queue Length

There are two main counters for the Disk Queue Length, the Average Disk Queue Length and the Current Disk Queue Length. There are arguments for only using either counter, so to stay out of the debate on which to use, we simply show values for both counters.

\PhysicalDisk(*)\Avg. Disk Queue Length

The Avg. Disk Queue Length counter is the “estimated” average number of requests that are either in process or waiting to be processed by the Disk.
Sustained counters above 5 per Disk could indicate a disk subsystem bottleneck. Remember to also keep an eye on the Pages/sec counter for low memory issues since low memory could cause Disk performance issues if the disk subsystem has to continuously process paging operations.

Microsoft® Description - Avg. Disk Queue Length is the average number of both read and write requests that were queued for the selected disk during the sample interval.

\PhysicalDisk(*)\Current Disk Queue Length

The Current Disk Queue Length counter is the actual number of requests that are either in process or waiting to be processed by the Disk at the time the counter is captured.
Sustained counters above 5 per Disk could indicate a disk subsystem bottleneck. Remember to also keep an eye on the Pages/sec counter for low memory issues since low memory could cause Disk performance issues if the disk subsystem has to continuously process paging operations.

Microsoft® Description - Current Disk Queue Length is the number of requests outstanding on the disk at the time the performance data is collected. It also includes requests in service at the time of the collection. This is a instantaneous snapshot, not an average over the time interval. Multi-spindle disk devices can have multiple requests that are active at one time, but other concurrent requests are awaiting service. This counter might reflect a transitory high or low queue length, but if there is a sustained load on the disk drive, it is likely that this will be consistently high. Requests experience delays proportional to the length of this queue minus the number of spindles on the disks. For good performance, this difference should average less than two.

Disk Latency and Fragmentation

\PhysicalDisk(*)\Avg. Disk sec/Read

The Avg. Disk sec/Read displays how long in milliseconds it takes for a read operation from the Disk. Watch this counter during times of heavy disk utilization to see if your system would benefit from a more robust Disk Subsystem (such as advanced RAID or newer flash drive technologies).

Microsoft® Description - Avg. Disk sec/Read is the average time, in seconds, of a read of data from the disk.

\PhysicalDisk(*)\Avg. Disk sec/Write

The Avg. Disk sec/Write displays how long in milliseconds it takes for a write operation to the Disk. Watch this counter during times of heavy disk utilization to see if your system would benefit from a more robust Disk Subsystem (such as advanced RAID or newer flash drive technologies).

Microsoft® Description - Avg. Disk sec/Write is the average time, in seconds, of a write of data to the disk.

\PhysicalDisk(*)\Split IO/sec

The Split IO/sec counter displays the physical disk requests that are split into multiple requests. This counter is a primary indicator if a disk is fragmented and needs to be optimized.

Performance Counters CPU/System Stats

CPU/System Stats

In addition to the % Processor Usage counters above, there are additional counters that can detect how the Processor is being worked and if the Processor Subsystem could potentially be a bottleneck.

\Processor(_total)\% Privileged Time

The Processor(_total)\% Privileged Time counter shows the percent of time that the processor is spent executing in Kernel (or Privileged) mode. Privileged mode includes services interrupts inside Interrupt Service Routines (ISRs), executing Deferred Procedure Calls (DPCs), Device Driver calls and other kernel-mode functions of the Windows® Operating System.
Most of the time a processor should be executing User mode operations, a high % privileged time might indicate a poorly written device driver or a faulty piece of hardware.

Microsoft® Description - % Privileged Time is the percentage of elapsed time that the process threads spent executing code in privileged mode. When a Windows system service in called, the service will often run in privileged mode to gain access to system-private data. Such data is protected from access by threads executing in user mode. Calls to the system can be explicit or implicit, such as page faults or interrupts. Unlike some early operating systems, Windows uses process boundaries for subsystem protection in addition to the traditional protection of user and privileged modes. Some work done by Windows on behalf of the application might appear in other subsystem processes in addition to the privileged time in the process.

\Processor(_total)\% User Time

The Processor(_total)\% User Time counter shows the percent of time that the processor(s) is spent executing in User mode.

Microsoft® Description - % User Time is the percentage of elapsed time the processor spends in the user mode. User mode is a restricted processing mode designed for applications, environment subsystems, and integral subsystems. The alternative, privileged mode, is designed for operating system components and allows direct access to hardware and all memory. The operating system switches application threads to privileged mode to access operating system services. This counter displays the average busy time as a percentage of the sample time.

\System\Processor Queue Length

The Processor Queue Length shows the number of threads that are observed as delayed in the processor Ready Queue and are waiting to be executed.
On single core machines, a sustained value over 5-10 or so may indicate that the workload on the system is more than the processor can handle. On multi-core systems, a good rule of thumb is to divide the Queue Length by the number of cores in the system and use the same indication above with that calculated value.
Note that the Processor Queue Length is an instantaneous counter, whereas the % Processor Usage counters are continuously measured counters that are averaged. There could be some disconnect between these counters because of this.

Microsoft® Description - Processor Queue Length is the number of threads in the processor queue. Unlike the disk counters, this counter counters, this counter shows ready threads only, not threads that are running. There is a single queue for processor time even on computers with multiple processors. Therefore, if a computer has multiple processors, you need to divide this value by the number of processors servicing the workload. A sustained processor queue of less than 10 threads per processor is normally acceptable, dependent of the workload.

Performance Counters - Physical Memory

Physical Memory

The Physical Memory Statistics Graph shows the available Performance Counters for everything that consumes "Physical Memory" on a Windows® Server. In theory, adding all of these counters together should equal the amount of RAM installed, but in practice this does not work. This is the result of Windows ® using shared DLLs and some RAM allocations that are not counted anywhere (such as trimmed working set pages that have yet to be written to disk).

\Memory\Available Bytes

The Available Bytes counter is the pool size of available pages in RAM that the system uses to satisfy requests for new pages. There are multiple counters available for convenience that provide this information, such as Available Mbytes, but this program uses the Available Bytes counter and does the calculation when generating the graphs.
Usually when this value is approximately at least 10% of total system memory, the system has an adequate amount of memory. However when this value is below 10% you must use additional counters, such as Pages/sec to determine if System memory is adequate for the workload.
Note that the "\Memory\Available Bytes" counter is an instantaneous counter (sampled once during the measurement period).

Microsoft® Description - Available Bytes is the amount of physical memory, in bytes, immediately available for allocation to a process or for system use. It is equal to the sum of memory assigned to the standby (cached), free and zero page lists.

\Process(_Total)\Working Set

The Working Set counter is the total amount of resident pages allocated in RAM that all the processes that are running on the system can address without causing a Page Fault. The value of this counter is in bytes, but this program does the calculation to MB when it creates the graphs.
Note that the "\Process(_Total)\Working Set" counter is an instantaneous counter (sampled once during the measurement period).

Microsoft® Description - Working Set is the current size, in bytes, of the Working Set of this process. The Working Set is the set of memory pages touched recently by the threads in the process. If free memory in the computer is above a threshold, pages are left in the Working Set of a process even if they are not in use. When free memory falls below a threshold, pages are trimmed from Working Sets. If they are needed they will then be soft-faulted back into the Working Set before leaving main memory.

\Memory\Cache Bytes

The Memory pages that the System uses are counted in two main counters, Cache Bytes and Pool Nonpaged Bytes.
The Cache Bytes counter is the amount of resident pages allocated in RAM that the Kernel threads can address without causing a Page Fault. This counter includes the Pool Paged Resident Bytes, the System Cache Resident Bytes, the System Code Resident Bytes and the System Driver Resident Bytes.
Note that the "\Memory\Cache Bytes" counter is an instantaneous counter (sampled once during the measurement period).

Microsoft® Description - Cache Bytes the size, in bytes, of the portion of the system file cache which is currently resident and active in physical memory. The Cache Bytes and Memory\\System Cache Resident Bytes counters are equivalent. This counter displays the last observed value only; it is not an average.

\Memory\Pool Nonpaged Bytes

The Pool Nonpaged Bytes counter is the amount of resident pages in RAM that the Kernel is using that cannot be paged out.
The Pool Nonpaged Bytes counter is also referred to as "Kernel Memory". If you ever run into any issues with Kernel Memory note that it is extremely difficult to troubleshoot as you have to use Kernel level tools such as "poolmon" to track what is causing the issues.
Also note that Microsoft Windows has limits on how much physical memory can be consumed by Kernel Memory. For instance Windows Server 2008 has a maximum limit of 75% of the amount of Physical Memory. If Kernel Memory reaches that Windows will in fact crash! Refer to the excellent WinInternals reference manuals for more information.
Note that the “\Memory\Pool Nonpaged Bytes” counter is an instantaneous counter (sampled once during the measurement period).

Microsoft® Description - Pool Nonpaged Bytes is the size, in bytes, of the nonpaged pool, an area of the system virtual memory that is used for objects that cannot be written to disk, but must remain in physical memory as long as they are allocated. Memory\\Pool Nonpaged Bytes is calculated differently than Process\\Pool Nonpaged Bytes, so it might not equal Process(_Total)\\Pool Nonpaged Bytes. This counter displays the last observed value only; it is not an average.