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Log Session Parameter Options

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In the Log Session Parameter Options tab, you can specify the values of variable features of a trace session.

You can set and change the values of the following options while creating a trace session. Several options can be changed while a trace session is running. The options that you cannot change appear dimmed ("greyed out") in the Log Session Parameter Options dialog box.

Flags
Specifies the trace flags for the trace provider. Trace flags determine which trace messages the provider generates. The meaning of the flags are determined independently by each provider.

If TraceView can find a trace message control (.tmc) file for the provider, you can select flags and a level from a list displayed in the Tracing Flags and Level Selection dialog box. To open the Tracing Flags and Level Selection dialog box, click the SET value of the Flags or Level option in the Log Session Parameter Options dialog box.

Flush Time (S)
Specifies how often (in seconds) the trace session buffers are flushed to a trace log or the TraceView display. The default is 1 (second).

These forced flushes occur in addition to the flushes that happen automatically when a buffer is full. A value of 0 means no forced flushes.

To flush more frequently than once per second, use the Buffer Size option to reduce the size of each buffer.

You can change the Flush Time value while the trace session is running.

Maximum Buffers
Specifies the maximum number of buffers that are allocated for the trace session.

The default value is determined by the number of processors, the amount of physical memory, and the operating system that you are using. You can change this value while the trace session is running.

Minimum Buffers
Specifies the number of buffers that are initially allocated for storing trace messages.

When the buffers are full, more buffers are allocated until the number of buffers reaches the value specified in the Maximum Buffers option. The default value is determined by the number of processors, the amount of physical memory, and the operating system in use. You cannot change this value while the trace session is running.

Buffer Size
Specifies the size, in kilobytes (KB), of each buffer that is allocated for the trace session. The default value is determined by the number of processors, the amount of physical memory, and the operating system in use. You cannot change this value while the trace session is running.

Decay Time (Minutes)
Specifies how long (in minutes) unused trace buffers are kept before they are freed. The default value is 15. The value of this option is displayed in the Age column of the Trace Session List.

This parameter is valid only on Windows 2000. You cannot change this value while the trace session is running.

Circular Buffer Size (MB)
Specifies that the trace buffers be circular and specifies the maximum size (in MB) of each buffer.

When a circular buffer is full, new trace messages are written to the beginning of the buffer, overwriting the oldest trace messages. By default, trace buffers are sequential, not circular.

You cannot change this value while the trace session is running.

Sequential Buffer Size (MB)
Specifies whether the trace buffers are sequential and specifies the maximum size (in MB) of each buffer.

When a sequential buffer is full, trace messages are written to another buffer or are lost. By default, trace buffers are sequential, not circular, and are 200 MB each.

You cannot change this value while the trace session is running.

Start New File After Buffer Size (MB)
Creates a new trace log file (.etl) whenever the existing log reaches the specified value. The value specifies the maximum size of each log file in MB.

The value of this option is displayed in the New File column of the Trace Session List.

This option is effective only when the provider is generating trace logs, that is, when you have selected the Log Trace Event Data to File option on the Log Session Options page. This option has no effect on circular buffers or on logs from an NT Kernel Logger trace session. It is not supported on Windows 2000.

Use Global Sequence Numbers
Generates a global sequence number for each trace message.

Global sequence numbers are unique for all trace sessions on the computer. The default value of this option is FALSE.

This option is not supported on Windows 2000 and has no effect on logs from an NT Kernel Logger trace session.

Use Local Sequence Number
Generates a local sequence number for each trace message. The default value is TRUE.

Local sequence numbers are unique within a trace session.

This option is not supported on Windows 2000 and has no effect on logs from an NT Kernel Logger trace session.

Level
Specifies a trace level for the trace provider. The trace level determines which trace messages the provider generates. The meaning of the level value is determined independently by each provider. Typically, it represents increasing levels of detail.

If TraceView can find a trace message control (.tmc) file for the provider, you can select flags and a level from a list displayed in the Tracing Flags and Level Selection dialog box. To open the Tracing Flags and Level Selection dialog box, click the SET value of the Flags or Level option in the Log Session Parameter Options dialog box.

For more information about trace levels, see the description of the EnableLevel parameter of the EnableTrace function in the Microsoft Windows SDK.

WinDbg
Redirects trace messages to KD or WinDbg, whichever is enabled, in addition to displaying them in the TraceView window. This option also sets the buffer size to 3 KB, the maximum size that is permitted by WinDbg. The value that is displayed for the Buffer Size option is ignored.

To display trace messages in a debugger, wmitrace.dll and traceprt.dll must be in the debugger's search path on the host computer. These DLLs are included in Debugging Tools for Windows Also, to enable the debugger to find the trace message format (.tmf) files for the trace messages, the TMF files must be in the debugger's search path on the host computer. To set the debugger's search path, use the !wmitrace.searchpath specialized debugger extension or set the value of the %TRACE_FORMAT_SEARCH_PATH% environment variable. For information about WinDbg and WMI Tracing Extensions, see Debugging Tools for Windows.

Ignore TraceView
Suppresses trace messages that result from TraceView operations.

Virtual File Size
Indicates the maximum number of trace messages that TraceView stores before it begins overwriting the oldest messages to make room for newer messages.

A value of 0 means that there is no maximum value. TraceView retains all messages and never overwrites them. The default value of this option, 65536, is the value recommended for most systems. Larger values might cause significant delays.

This value appears in the Max Trace Records column of the Trace Session List.