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H5P_SET_FAPL_LOG

Sets up the logging virtual file driver (H5FD_LOG) for use

Procedure:

H5P_SET_FAPL_LOG ( fapl_id, logfile, flags, buf_size )

Signature:

herr_t H5Pset_fapl_log(
                        hid_t fapl_id,
                        const char *logfile,
                        unsigned long long flags,
                        size_t buf_size
    )
  

Parameters:
hid_t fapl_idIN: File access property list identifier
char *logfileIN: Name of the log file
unsigned long long flags    IN: Flags specifying the types of logging activity
size_t buf_sizeIN: The size of the logging buffers, in bytes (see description)

Description:

H5P_SET_FAPL_LOG modifies the file access property list to use the logging driver, H5FD_LOG. The logging virtual file driver (VFD) is a clone of the standard SEC2 (H5FD_SEC2) driver with additional facilities for logging VFD metrics and activity to a file.

logfile is the name of the file in which the logging entries are to be recorded.

The actions to be logged are specified in the parameter flags using the pre-defined constants described in the following table. Multiple flags can be set through the use of a logical OR contained in parentheses. For example, logging read and write locations would be specified as (H5FD_LOG_LOC_READ|H5FD_LOG_LOC_WRITE).

 
Table 1:   Logging flags
 

Flag

Description

H5FD_LOG_LOC_READ

Track the location and length of every read, write, or seek operation.

H5FD_LOG_LOC_WRITE  

H5FD_LOG_LOC_SEEK

H5FD_LOG_LOC_IO

Track all I/O locations and lengths. The logical equivalent of the following:

(H5FD_LOG_LOC_READ | H5FD_LOG_LOC_WRITE | H5FD_LOG_LOC_SEEK)

H5FD_LOG_FILE_READ

Track the number of times each byte is read or written.

H5FD_LOG_FILE_WRITE  

H5FD_LOG_FILE_IO

Track the number of times each byte is read and written. The logical equivalent of the following:

(H5FD_LOG_FILE_READ | H5FD_LOG_FILE_WRITE)

H5FD_LOG_FLAVOR

Track the type, or flavor, of information stored at each byte.

H5FD_LOG_NUM_READ

Track the total number of read, write, seek, or truncate operations that occur.

H5FD_LOG_NUM_WRITE

H5FD_LOG_NUM_SEEK

H5FD_LOG_NUM_TRUNCATE

 

H5FD_LOG_NUM_IO

Track the total number of all types of I/O operations. The logical equivalent of the following:

(H5FD_LOG_NUM_READ | H5FD_LOG_NUM_WRITE | H5FD_LOG_NUM_SEEK | H5FD_LOG_NUM_TRUNCATE)

H5FD_LOG_TIME_OPEN

Track the time spent in open, stat, read, write, seek, or close operations.

H5FD_LOG_TIME_STAT

H5FD_LOG_TIME_READ

H5FD_LOG_TIME_WRITE

H5FD_LOG_TIME_SEEK

H5FD_LOG_TIME_CLOSE

 

H5FD_LOG_TIME_IO

Track the time spent in each of the above operations. The logical equivalent of the following:

(H5FD_LOG_TIME_OPEN | H5FD_LOG_TIME_STAT | H5FD_LOG_TIME_READ | H5FD_LOG_TIME_WRITE | H5FD_LOG_TIME_SEEK | H5FD_LOG_TIME_CLOSE)

H5FD_LOG_ALLOC

Track the allocation of space in the file.

H5FD_LOG_ALL

Track everything. The logical equivalent of the following:

(H5FD_LOG_ALLOC | H5FD_LOG_TIME_IO | H5FD_LOG_NUM_IO | H5FD_LOG_FLAVOR | H5FD_LOG_FILE_IO | H5FD_LOG_LOC_IO)

The logging driver can track the number of times each byte in the file is read from or written to (using H5FD_LOG_FILE_READ and H5FD_LOG_FILE_WRITE) and what kind of data is at that location (e.g., metadata, raw data; using H5FD_LOG_FLAVOR). This information is tracked in internal buffers of size buf_size, which must be at least the maximum size in bytes of the file to be logged while the log driver is in use.

One buffer of size buf_size will be created for each of H5FD_LOG_FILE_READ, H5FD_LOG_FILE_WRITE and H5FD_LOG_FLAVOR when those flags are set; these buffers will not grow as the file increases in size.

 

 

Output:

This section describes the logging driver (LOG VFD) output.

The table, immediately below, describes output of the various logging driver flags and function calls; error output is in red italic. A list of valid flavor values, describing the type of data stored, follows the table.

 
Table 2:   Logging output
 

Flag (H5FD_LOG_)

VFD Call

Output and Comments

LOC_READ

Read()

%10a-%10a (%10Zu bytes) (%s) Read

Start position
End position
Number of bytes
Flavor of read

Adds (%f s) and seek time if TIME_SEEK is also set.

LOC_READ

Read() Error

Error! Reading: %10a-%10a (%10Zu bytes)

Same parameters as non-error entry.

LOC_WRITE

Write()

%10a-%10a (%10Zu bytes) (%s) Written

Start position
End position
Number of bytes
Flavor of write

Adds (%f s) and seek time if TIME_SEEK is also set.

LOC_WRITE

Write() Error

Error! Writing: %10a-%10a (%10Zu bytes)

Same parameters as non-error entry.

LOC_SEEK

Read()
Write()

Seek: From %10a-%10a

Start position
End position

Adds (%f s) and seek time if TIME_SEEK is also set.

FILE_READ

Close()

Begins with:
Dumping read I/O information

Then, for each range of identical values, there is this line:
\tAddr %10-%10 (%10lu bytes) read from %3d times

Start address
End address
Number of bytes
Number of times read

Note: The data buffer is scanned and each range of identical values gets one entry in the log file to save space and make it easier to read.

FILE_WRITE

Close()

Begins with:
Dumping write I/O information

Then, for each range of identical values, there is this line:
\tAddr %10-%10 (%10lu bytes) written to %3d times

Start address
End address
Number of bytes
Number of times written

Note: The data buffer is scanned and each range of identical values gets one entry in the log file to save space and make it easier to read.

FLAVOR

Close()

Begins with:
Dumping I/O flavor information

Then, for each range of identical values, there is this line:
\tAddr %10-%10 (%10lu bytes) flavor is %s

Start address
End address
Number of bytes
Flavor

Note: The data buffer is scanned and each range of identical values gets one entry in the log file to save space and make it easier to read.

NUM_READ

Close()

Total number of read operations: %11u

NUM_WRITE

Close()

Total number of write operations: %11u

NUM_SEEK

Close()

Total number of seek operations: %11u

NUM_TRUNCATE

Close()

Total number of truncate operations: %11u

TIME_OPEN

Open()

Open took: (%f s)

TIME_READ

Close()
Read()

Total time in read operations: %f s

See also:   LOC_READ

TIME_WRITE

Close()
Write()

Total time in write operations: %f s

See also:   LOC_WRITE

TIME_SEEK

Close()
Read()
Write()

Total time in seek operations: %f s

See also:   LOC_SEEK  or  LOC_WRITE

TIME_CLOSE

Close()

Close took: (%f s)

TIME_STAT

Open()

Stat took: (%f s)

ALLOC

Alloc()

%10-%10 (%10Hu bytes) (%s) Allocated

Start of address space
End of address space
Total size of allocation
Flavor of allocation

 

Flavors:
The flavor describes the type of stored information. The following table lists the flavors that appear in log output and briefly describes each. These terms are provided here to aid in the construction of log message parsers; a full description is beyond the scope of this document.

 

 
Table 3:   Flavors of logged data
 

Flavor

Description

H5FD_MEM_NOLIST

Error value

H5FD_MEM_DEFAULT

Value not yet set.
May also be a datatype set in a larger allocation that will be suballocated by the library.

H5FD_MEM_SUPER

Superblock data

H5FD_MEM_BTREE

B-tree data

H5FD_MEM_DRAW

Raw data (for example, contents of a dataset)

H5FD_MEM_GHEAP

Global heap data

H5FD_MEM_LHEAP

Local heap data

H5FD_MEM_OHDR

Object header data

Returns:

Returns non-negative if successful. Otherwise returns negative.

Example:

Coming Soon!

History:
1.8.7The flags parameter has been changed from unsigned int to unsigned long long.
The implementation of the H5FD_LOG_TIME_OPEN, H5FD_LOG_TIME_READ, H5FD_LOG_TIME_WRITE, and H5FD_LOG_TIME_SEEK flags has been finished.
New flags were added: H5FD_LOG_NUM_TRUNCATE and H5FD_LOG_TIME_STAT.
1.6.0The verbosity parameter has been removed.
Two new parameters have been added: flags of type unsigned and buf_size of type size_t.
1.4.0Function introduced in this release.

--- Last Modified: December 04, 2017 | 08:41 AM