Administration Reference

fstrace dump

Purpose

Dumps a trace log

Synopsis

fstrace dump [-set <set_name>⁺]  [-follow <log_name>]  
             [-file <output_filename>]  
             [-sleep <seconds_between_reads>]  [-help]
   
fstrace d [-se <set_name>⁺]  [-fo <log_name>]  [-fi <output_filename>] 
          [-sl <seconds_between_reads>]  [-h]

Description

The fstrace dump command displays the current contents of the cmfx trace log on the standard output stream or writes it to the file named by the -file argument.

To write the log continuously to the standard output stream or to a file, use the -follow argument. By default, the log's contents are written out every ten seconds and then automatically cleared. To change the interval between writes, use the -sleep argument.

Cautions

This command produces output only if the cm event set is active. To display or set the event set's state, use the fstrace lsset or fstrace setset command respectively.

To make the output from this command maximally readable, the message catalog file called afszcm.cat must reside in the local /usr/vice/etc/C directory. If necessary, copy the file to that directory from the AFS Binary Distribution before activating tracing.

When the cm event set is active, a defined amount of kernel memory (by default, 60 KB) is allocated for the cmfx trace log. As described on the introductory fstrace reference page, when the buffer is full, messages are overwritten in a circular fashion (new messages overwrite the oldest ones). To allocate more kernel memory for the log, use the fstrace setlog command; to display the log buffer's current size, use the fstrace lslog command with the -long argument.

Options

-set

Names the event set for which to write out the associated trace log. The only acceptable value is cm (for which the associated trace log is cmfx). Provide either this argument or the -log argument, or omit both to write out the cmfx log by default.

-follow

Names the trace log to write out continuously at a specified interval (by default, every ten seconds; use the -sleep argument to change the interval). The log is cleared after each write operation.

The only acceptable value is cmfx. Provide either this argument or the -set argument, or omit both to write out the cmfx log by default.

-file

Specifies the pathname of the file to which to write the trace log's contents. It can be in AFS or on the local disk. Partial pathnames are interpreted relative to the current working directory. If this argument is omitted, the trace log appears on the standard output stream.

-sleep

Sets the number of seconds between writes of the trace log's contents when it is dumped continuously. Provide the -follow argument along with this one. If this argument is omitted, the default interval is ten seconds.

-help

Prints the online help for this command. All other valid options are ignored.

Output

The output begins with a header specifying the date and time at which the write operation began. If the -follow argument is not included, the header also reports the number of logs being dumped; it is always 1, since there is only the cmfx trace log. The format of the header is as follows:

   AFS Trace Dump -
     Date: starting_timestamp
   Found 1 logs.
   Contents of log cmfx:

Each subsequent message describes a Cache Manager operation in the following format:

   time timestamp, pid pid:event_message

where

timestamp: Specifies the time at which the Cache Manager performed the operation, as the number of seconds since the dump began
pid: Specifies the process ID of the process or thread associated with the message
event_message: Is the message itself. They are generally meaningful only to someone familiar with the AFS source code.

In addition, every 1024 seconds the fstrace command interpreter writes a message that records the current clock time, in the following format:

   time timestamp, pid pid: Current time: unix_time

where

timestamp: Is the number of seconds from the start of trace logging
pid: Is the process ID number
unix_time: Is the machine's clock time, represent in the standard UNIX time format as the number of seconds since midnight on January 1, 1970.

Use this message to determine the actual clock time associated with each log message. Determine the actual time as follows:

Locate the message of interest.
Search backward through the trace file for the closest current time message.
If the current time message's timestamp is smaller than the log message's timestamp, subtract former from the latter. If the current time message's timestamp is larger than the log message's timestamp, add 1024 to the latter and subtract the former from the result.
Add the resulting number to the current time message's unix_time to determine the log message's actual time.

If any of the data in the kernel trace buffer has been overwritten since tracing was activated, the following message appears at the appropriate place in the output:

   Log wrapped; data missing.

To reduce the likelihood of overwriting, use the fstrace setlog command to increase the kernel buffer's size. To display the current defined buffer size, use the fstrace lslog command with the -long argument.

The following message at the end of the log dump indicates that it is completed:

   AFS Trace Dump - Completed

Examples

The following command dumps the log associated with the cm event set to the standard output stream.

   # fstrace dump -set cm
   AFS Trace Dump -
      Date: Tue Apr  7 10:54:57 1998
   Found 1 logs.
   time 32.965783, pid 0: Tue Apr  7 10:45:52 1998
   time 32.965783, pid 33657: Close 0x5c39ed8 flags 0x20 
   time 32.965897, pid 33657: Gn_close vp 0x5c39ed8 flags 0x20 (returns 0x0) 
   time 35.159854, pid 10891: Breaking callback for 5bd95e4 states 1024 (volume 0)
   time 35.407081, pid 10891: Breaking callback for 5c0fadc states 1024 (volume 0)
                                    .
                                    .
                                    .
   time 71.440456, pid 33658: Lookup adp 0x5bbdcf0 name g3oCKs \
        fid (756 4fb7e:588d240.2ff978a8.6) 
   time 71.440569, pid 33658: Returning code 2 from 19 
   time 71.440619, pid 33658: Gn_lookup vp 0x5bbdcf0 name g3oCKs (returns 0x2) 
   time 71.464989, pid 38267: Gn_open vp 0x5bbd000 flags 0x0 (returns 0x0) 
   AFS Trace Dump - Completed

The following command dumps the trace log associated with the cm event set on the local machine to the file cmfx.dump.file.1, using the default interval of 10 seconds between successive dumps:

   # fstrace dump -follow cmfx -file cmfx.dump.file.1

Privilege Required

The issuer must be logged in as the local superuser root.

Related Information