OWFS Statistics

• Synopsis

  OWFS keeps track of internal data, such as number of 1-wire bus errors, amount of data sent, and time the bus is busy. This data might be useful for monitoring the health of the network, the excess capacity of the bus, or the efficiency of the implementation. You can also ignore the statistics. They are not essential for using the OWFS system.
  

  All the statistics data is presented in the same form as the rest of the 1-wire bus data: files and directories for OWFS, or web page fields for owhttpd.

• Structure

  The directory structure (for the filesystem representation) of statistics looks like this:

  |--statistics |   |-- bus |   |-- cache |   |   |-- directory |   |   |-- external |   |   |-- internal |   |   |-- persistent |   |   |-- primary |   |   `-- secondary |   |-- directory |   |   |-- bus |   |   `-- device |   |-- read |   |-- threads |   |   |-- directory |   |   |-- overall |   |   |-- read |   |   `-- write |   `-- write

  The individual entries are:

  bus |-- CRC16_errors |-- CRC16_tries |-- CRC8_errors |-- CRC8_tries |-- bus_time |-- elapsed_time |-- locks |-- pause_time |-- read_timeout `-- unlocks

  cache |-- additions |-- directory |   |-- added |   |-- deleted |   |-- expired |   |-- hits |   `-- tries |-- external |   |-- added |   |-- deleted |   |-- expired |   |-- hits |   `-- tries |-- flips |-- internal |   |-- added |   |-- deleted |   |-- expired |   |-- hits |   `-- tries |-- persistent |   |-- max |   |-- now |   |-- num |   `-- sum |-- primary |   |-- max |   |-- now |   |-- num |   `-- sum `-- secondary     |-- max     |-- now     |-- num     `-- sum

  directory |-- bus |   |-- calls |   `-- entries |-- device |   |-- calls |   `-- entries `-- maxdepth

  read |-- bytes |-- cachebytes |-- cachesuccess |-- calls |-- success |-- tries.0 |-- tries.1 |-- tries.2 `-- tries.ALL

  threads |-- device_slots |-- directory |   |-- max |   |-- now |   |-- num |   `-- sum |-- multithreading |-- overall |   |-- max |   |-- now |   |-- num |   `-- sum |-- read |   |-- max |   |-- now |   |-- num |   `-- sum `-- write     |-- max     |-- now     |-- num     `-- sum

  write |-- bytes |-- calls |-- success |-- tries.0 |-- tries.1 |-- tries.2 `-- tries.ALL

  
  
• Use
  

  Example bash shell scripts:
  Note, all these scripts reference from the root mounted owfs directory, and use the external bc command for floating point calculations.
  

  • CRC error rates
    for x in 8 16
  do echo "CRC${x} error rate %: "
  echo "scale=2 ; `cat statistics/bus/CRC${x}_errors`*100/`cat statistics/bus/CRC${x}_tries`" | bc
done


  • BUS utilization
    echo "scale=2 ; 100*`cat statistics/bus/bus_time`/`cat statistics/bus/elapsed_time`" | bc


  • BUS locks / second
echo "scale=3 ; `cat statistics/bus/locks`/`cat statistics/bus/elapsed_time`" | bc

    
  • Cache hit rate
    echo "scale=2 ; 100*`cat statistics/cache/hits`/`cat statistics/cache/tries`" | bc

    
  • Directory lengths
    for x in bus device
  do echo "Average length for $x: "
  echo "scale=1 ; `cat statistics/directory/$x/entries`/`cat statistics/directory/$x/calls`" | bc
done

    
  • Read success rate
    echo "`cat statistics/read/calls` attempted reads"
echo -n "  Success from cache %"
  echo "scale=2; 100*`cat statistics/read/cachesuccess`/`cat statistics/read/calls` | bc
echo -n "  Success on 1st try %"
  echo "scale=2; 100*(`cat statistics/read/tries.0`-`cat statistics/read/tries.1`)/`cat statistics/read/calls` | bc
echo -n "  Success on 2nd try %"
  echo "scale=2; 100*(`cat statistics/read/tries.1`-`cat statistics/read/tries.2`)/`cat statistics/read/calls` | bc
echo -n "  Success on 3rd try %"
  echo "scale=2; 100*(`cat statistics/read/tries.2`-(`cat statistics/read/calls`-`cat statistics/read/success`))/`cat statistics/read/calls` | bc
echo -n "  Failure %"
  echo "scale=2; 100*(`cat statistics/read/calls`-`cat statistics/read/success`)/`cat statistics/read/calls` | bc


  • Write success rate
    echo "`cat statistics/write/calls` attempted writes"
echo -n "  Success on 1st try %"
  echo "scale=2; 100*(`cat statistics/write/tries.0`-`cat statistics/write/tries.1`)/`cat statistics/write/calls` | bc
echo -n "  Success on 2nd try %"
  echo "scale=2; 100*(`cat statistics/write/tries.1`-`cat statistics/write/tries.2`)/`cat statistics/write/calls` | bc
echo -n "  Success on 3rd try %"
  echo "scale=2; 100*(`cat statistics/write/tries.2`-(`cat statistics/write/calls`-`cat statistics/write/success`))/`cat statistics/write/calls` | bc
echo -n "  Failure %"
  echo "scale=2; 100*(`cat statistics/write/calls`-`cat statistics/write/success`)/`cat statistics/write/calls` | bc


  • Thread count average
    echo "scale=3 ; `cat statistics/bus/locks`/`cat statistics/bus/elapsed_time`" | bc
for x in read write directory overall
  do echo -n "Average thread count ($x): "
  echo "scale=2; `cat statistics/thread/$x/sum`/`cat statistics/thread/$x/num`" | bc
done

    
  • Threads / second
    for x in read write directory overall
  do echo -n "Threads per second ($x): "
  echo "scale=2; `cat statistics/thread/$x/num`/`cat statistics/bus/elapsed_time`" | bc
done

    
• Details

  Heading	Subheading	Field	Explanation
  bus		CRC16_errors	Errors found in CRC16 check.
  		CRC16_tries	Calls to CRC16 check. Used for some memory reads and writes to ensure accuracy.
  		CRC8_errors	Errors in CRC8 calls. (At least one at end of every directory search).
  		CRC8_tries	Calls to CRC8 check (used extensively in device directory searches).
  		bus_time	Time the bus has been locked. (Includes pause_time).
  		elapsed_time	Time the system has been up. (In seconds).
  		locks	The number of times the 1-wire bus has been "locked" for exclusive use for communication
  		pause_time	Time (in seconds) the bus has paused in locked state. Usually for powering parasitic chips for temperature conversions.
  		read_timeout	The number of times the 1-wire bus communication response has been tardy.
  		unlocks	The number of times the 1-wire bus has been "unlocked". Should be slightly less than or equal to "locks".
  cache		additions	Items added to the cache. (Can be the same value, multiple times if it has timed out).
  	directory external internal	added	Items added to the cache tables. (Note, this is total successful additions, many will have expired, or overwritten previous entries). directory Caching of directory entries (devices scanned on the main 1-wire bus or a branch) external Device properties requested (like temperature or memory contents). internal Device properties remembered, but no neccessarily displayed (like temperature resolution or voltage source).
  	directory external internal	deleted	Items deleted from the cache tables. Total successful deletions, may have been readded. directory Caching of directory entries (devices scanned on the main 1-wire bus or a branch) external Device properties requested (like temperature or memory contents). internal Device properties remembered, but no neccessarily displayed (like temperature resolution or voltage source).
  	directory external internal	expired	Items that were found to be too old when attempted to be read. Perhaps the timeout period needs adjusting. directory Caching of directory entries (devices scanned on the main 1-wire bus or a branch) external Device properties requested (like temperature or memory contents). internal Device properties remembered, but no neccessarily displayed (like temperature resolution or voltage source).
  	directory external internal	hits	Items successfully retrieved from the cache. This avoided slow 1-wire bus activity. directory Caching of directory entries (devices scanned on the main 1-wire bus or a branch) external Device properties requested (like temperature or memory contents). internal Device properties remembered, but no neccessarily displayed (like temperature resolution or voltage source).
  	directory external internal	tries	Attempts at getting data from thbe cache instead of the 1-wire bus. directory Caching of directory entries (devices scanned on the main 1-wire bus or a branch) external Device properties requested (like temperature or memory contents). internal Device properties remembered, but no neccessarily displayed (like temperature resolution or voltage source).
  		flips	Times the entire cache database has expired and been restarted.
  	persistent primary secondary	max	Maximum number of items ever in database. persistent Storage for items that persist, like cumulative counters. primary Active database, cache items added to this list. secondary Past database. Used until it times out, then recycled to active.
  	persistent primary secondary	now	Current number of items in database. persistent Storage for items that persist, like cumulative counters. primary Active database, cache items added to this list. secondary Past database. Used until it times out, then recycled to active.
  	persistent primary secondary	num	Number of cache add  passes (ever) to database. persistent Storage for items that persist, like cumulative counters. primary Active database, cache items added to this list. secondary Past database. Used until it times out, then recycled to active.
  	persistent primary secondary	sum	Sum of database size at each pass (for averaging). persistent Storage for items that persist, like cumulative counters. primary Active database, cache items added to this list. secondary Past database. Used until it times out, then recycled to active.
  directory	bus device	calls	Calls to list the contents of  directory. bus Directory is the root, or a DS2409 branch (main or aux) device Directory is within a 1-wire chip, or a stats catagory. Includes subdirectories like page/...
  	bus device	entries	Each element of a directory. bus Directory is the root, or a DS2409 branch (main or aux) device Directory is within a 1-wire chip, or a stats catagory. Includes subdirectories like page/...
  		maxdepth	Maximum level of  branching found (Each DS2409 level adds one).
  read		bytes	Total bytes read (Includes bytes from 1-wire bus and bytes from in-memory information)/
  		cachebytes	Bytes read in data cache
  		cachesuccess	Number of cache read attempts that were successful
  		calls	Attempts at reading from owfs
  		success	Successful attempts read from owfs. Includes data, memory and cache successes.
  		tries.[0 1 2]	Attempts to read once, twice or three times. If all three unsuccessful, success not incremented
  threads		device_slots	How many device locking slots are available (for simultaneous operation.
  	directory overall read write	max	maximum number of simultaneous threads directory threads for directory listing overall all threads read threads for reading data write threads for writing data
  	directory overall read write	now	current number of simultaneous threads directory threads for directory listing overall all threads read threads for reading data write threads for writing data
  	directory overall read write	num	number of threads created threads directory threads for directory listing overall all threads read threads for reading data write threads for writing data
  	directory overall read write	sum	number of threads at each new thread (sum/num=average) directory threads for directory listing overall all threads read threads for reading data write threads for writing data
  		multithreading	1 if multithreading operational
  write		bytes	Total bytes written. (Includes bytes to 1-wire bus and bytes to  in-memory information)/
  		calls	Attempts at writing to owfs
  		success	Successful attempts writing to owfs. Includes data and memory.
  		tries.[0 1 2]	Attempts to write once, twice or three times. If all three unsuccessful, success not incremented