ctr_FsAccesslogAnalyzer

ctr_FsAccesslogAnalyzer is a tool for detecting what may be inefficient file access not intended by the developer and due to CTR file system properties, and so forth.
In most cases, Nintendo recommends resolving the warnings given by this tool. However, if the file access in question is intended by the developer or if there is no problem in the access speed itself, warnings given by this tool do not necessarily need to be resolved.

Also, this tool displays the following information in addition to warnings.

• File access statistics
• File access log format

Preparing for Use

Change the program so that the file access log is displayed.
Call nn::fs::SetAnalysisLog(true) in the fs library in the development build, and then all file access information beginning from [FS_ANALYSIS] will be output to the log during file access.
To stop log output, call nn::fs::SetAnalysisLog(false).

How to Use

By passing the obtained log output results to the tool as standard input (as follows), the analysis results will be output as standard output. (You can also pipeline output from the debugger as input to the tool.)

        ctr_FsAccesslogAnalyzer32.exe < input.txt

Strings other than the access log's can be contained in the log passed to this tool.

Notes

This tool does not support file access logs from CTR-SDK versions prior to 4.1.

Output is displayed in the following order: file access statistics, warnings, and then the file access log format.
The formats for each are as follows.

File Access Statistics Format

File access statistics for each archive are displayed in the following format.

Statistics
	Archive name
		Archive access statistic 1
		Archive access statistic 2
		Archive access statistic 3
	Archive name
		Archive access statistic 1
		Archive access statistic 2
		Archive access statistic 3

Supported archives:

• RomFs
  Access to the ROMFS archive
• SaveData
  Access to the save data archive
• ExtSaveData
  Access to the extended save data archive
• Sdmc
  Access to the SD Card archive

Information displayed for each archive:

• TotalReadSize
  Total size of reads from archive
• TotalReadCount
  Number of reads from archive
• MinReadSize
  Minimum size of reads from archive (specified)
• MaxReadSize
  Maximum size of reads from archive (specified)
• TotalWriteSize
  Total size of writes to archive
• TotalWriteCount
  Number of writes to archive
• MinWriteSize
  Minimum size of writes to archive (specified)
• MaxWriteSize
  Maximum size of writes to archive (specified)

Warnings

The type of warning and the history for the accesses that caused the warning are displayed in the following format.

Warnings
	Types of warnings
		File access history 1
		File access history 2
		File access history 3
		File access history 4
	Types of warnings
		File access history 1
		File access history 2

Types of warnings

• FrequencyFlush
  The same file is being written and flushed a large number of times in a short period of time.
  Nintendo recommends disabling flushing, write to a file, and then flushing only once.
  Also see Improved Use of the File System.
• FrequencySmallWrite
  A large number of small writes are being performed.
  Nintendo recommends performing a single batch write, because there is an overhead associated with each write.
  Also see Improved Use of the File System.
• FrequencyOpenClose
  The same file is being opened and closed a large number of times in a short period of time.
• FrequencyMountUnmount
  The same archive is being mounted and unmounted a large number of times in a short period of time.
• NotAlignedSequentialRead
  A buffer that is not 4-byte aligned is being passed to the file system.
  Alternatively, an archive is being accessed with a non-4-byte file offset.
  When boundaries are not aligned, the alignment is adjusted internally. This tends to decrease access speed.
  Misalignment is prone to occur while reading audio streaming playback data, which tends to cause skipping.
  

2012/04/26

Initial version.