dt-usersguide.txt

Linux磁盘测试的源代码,测试磁盘的读写性能

          and  then  a read verification pass is performed.  If you wish to
          prevent  the   read   verify   pass,   you   must   specify   the
          "disable=verify" option.

          Special Notes:
            o  Terminal devices are not closed between passes so previously
               set  terminal  characteristics  don't  get reset.  This also
               caused a race condition when doing loopback testing with two
               processes.



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          Users Manual for                              November 10th, 2000
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            o  When testing terminal (serial)  devices,  modem  control  is
               disabled (via setting CLOCAL) to prevent tests from hanging.
               If the "enable=modem" option is specified,  then  CLOCAL  is
               reset,  hangup  on  close HUPCL is set, and testing will not
               preceed until carrier or DSR is detected.  This code is  not
               fully  tested, but this description accurately describes the
               code.
            o  At the present time, tapes are rewound by closing  the  dev-
               ice, so you must specify the rewind device during testing if
               the read verify pass is being performed.   This  restriction
               will  probably change in the next release since magtape con-
               trol commands will be  supported  (tape  specific  tests  as
               well).
            o  A special check  is  made  for  the  /dev/  prefix,  and  if
               located,  the  O_CREAT  open  flag  is  cleared  to  prevent
               accidently creating files in this directory when not  speci-
               fying  the correct device name (very easy to do when running
               tests as super-user 'root').
            o  When writing to raw disks on Tru64 UNIX,  if  the  disk  was
               previously  labeled,  you must issue the "disklabel_-z" com-
               mand to destroy the label block or else you cannot write  to
               this  area  of  this  disk  (block  0).   Failure to do this
               results in the error "Read-only file  system"  (errno=EROFS)
               being returned on write requests.


              Syntax:
                  of=filename      The output file to write.


          4.3  Pattern File "pf=" Option.

               This option specifies a pattern file to  use  for  the  data
          pattern  during  testing.   This  option overrides the "pattern="
          option and allows you to specify specialized patterns.  The  only
          restriction  to  this  option is that the entire file must fit in
          memory.  A buffer is allocated to read the  entire  pattern  file
          into  memory before testing starts so performance is not affected
          by reading the pattern file.

              Syntax:
                  pf=filename      The data pattern file to use.


          4.4  Block Size "bs=" Option.

               This option specifies the block size, in bytes, to use  dur-
          ing  testing.   At  the  present  time, this option sets both the
          input and output block sizes.  At the  time  I  originally  wrote
          this  program,  I  didn't have the need for seperate block sizes,
          but this may change in a future release where I'll add  back  the



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          Users Manual for                              November 10th, 2000
          dt - Data Test Program                              Version 13.22



          "ibs=" & "obs=" options available with dd.

          Special Notes:
            o  When enabling variable length records via the "min=" option,
               this also sets the maximum record size to be written/read.
            o  For memory mapped files, the block size must be  a  multiple
               of the system dependent page size (normally 4k or 8k bytes).


              Syntax:
                  bs=value         The block size to read/write.


          4.5  Log File "log=" Option.

               This option specifies the log file to redirect  all  program
          output  to.  This is done by re-opening the standard error stream
          (stderr) to the specifed log file.  Since all output from  dt  is
          directed to stderr, library functions such as perror() also write
          to this log file.

          Special Notes:
            o  A seperate buffer is allocated for the  stderr  stream,  and
               this stream is set buffered so timing isn't affected by pro-
               gram output.
            o  When starting multiple processes via  the  "procs="  option,
               all  output  is  directed  to the same log file.  The output
               from each process is identified by the process ID  (PID)  as
               part of the message (errors & statistics).


              Syntax:
                  log=filename     The log file name to write.


          4.6  POSIX Asynchronous I/O "aios=" Option.

               This  option  enables  and  controls  the  number  of  POSIX
          Asychronous I/O requests used by the program.

          Special Notes:
            o  The default is to queue up to 8 requests.
            o  This option is only valid for Tru64 UNIX  systems  are  this
               time.
            o  The system limit for AIO on Tru64 UNIX is dynamic,  and  can
               be queried by using the "sysconfig_-q_rt" command.
            o  You can use the "enable=aio" option to enable  AIO  and  use
               the default request limit.
            o  AIO is only supported for character devices and is  disabled
               for  terminals.   On  Tru64 UNIX, you can alter the Makefile
               and  link  against  libaio.a,  which  allows  AIO  with  any



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          Users Manual for                              November 10th, 2000
          dt - Data Test Program                              Version 13.22



               device/file by mimic'ing AIO using POSIX threads.
            o  AIO requests can not be cancelled on Tru64 UNIX, so  queuing
               many  requests  to 1/2" tape devices will probably result in
               running off the end of the tape reel.  This is not a problem
               for cartridge tapes.


              Syntax:
                  aios=value       Set number of AIO's to queue.


          4.7  Buffer Alignment "align=" Option.

               This option controls the  alignment  of  the  normally  page
          aligned  data  buffer allocated.  This option is often useful for
          testing certain DMA boundary  conditions  not  easily  reproduced
          otherwise.   The  rotate  option  automatically  adjust  the data
          buffer pointer by (0, 1, 2, 3,  ...)  for  each  I/O  request  to
          ensure various boundaries are fully tested.

              Syntax:
                  align=offset     Set offset within page aligned buffer.
              or  align=rotate     Rotate data address through sizeof(ptr).


          4.8  File Disposition "dispose=" Option.

               This option controls the disposition of test  files  created
          on  file  systems.   By default, the test file created is deleted
          before exiting, but sometimes you may wish to keep this file  for
          further examination, for use as a pattern file, or simply for the
          read verify pass of another test  (e.g.,  reading  the  file  via
          memory map API).

              Syntax:
                  dispose=mode     Set file dispose to: delete or keep.


          4.9  Dump Data Limit "dlimit=" Option.

               This option allows you to specify the dump data  limit  used
          when  data  compare errors occur.  The default dump data limit is
          64 bytes.

              Syntax:
                  dlimit=value     Sets the data dump limit to value.








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          Users Manual for                              November 10th, 2000
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          4.10  Device Type "dtype=" Option.


          4.11  Input Device Type "idtype=" Option.


          4.12  Output Device Type "odtype=" Option.

               These options provide a method to inform dt of the  type  of
          device  test  to be performed.  Without this knowledge, only gen-
          eric testing is possible.

          Special Notes:
            o  On Tru64 UNIX systems,  these  options  are  not  necessary,
               since  this  information  is  obtained  via the DECIOCGET or
               DEVGETINFO IOCTL's:
            o  Although the program accepts a large number of device types,
               as  shown  below,  specific  tests  only  exists for "disk",
               "tape", "fifo", and "terminal" device types.  Others may  be
               added in the future.
            o  In the case of "disk" device type, dt reports  the  relative
               block number when read, write, or data compare errors occur.
            o  Also for "disk" devices, dt will automatically determine the
               disk  capacity  if  a data or record limit is not specified.
               This is done via a series of seek/read requests.
            o  On each operating system supported, string compares are done
               on  well known device names to automatically select the dev-
               ice type.  For example on QNX, "/dev/hd" for disk, "/dev/tp"
               for tapes, and "/dev/ser" for serial lines.
            o  The device type gets displayed in the total statictics.


              Syntax:
                  dtype=string    Sets the device type.
                  idtype=string   Sets the input device type.
                  odtype=string   Sets the output device type.

              The Valid Device Types Are:
                  audio     comm      disk      graphics  memory
                  mouse     network   fifo      pipe      printer
                  processor socket    special   streams   tape
                  terminal  unknown

          Note:  Although dt does not provide  specific  test  support  for
          each of the devices shown above, its' design makes it easy to add
          new device specific tests.  Specific  support  exists  for  disk,
          fifo,  pipe, tape, and terminals. Support for "ptys" may be added
          in the future as well.






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          Users Manual for                              November 10th, 2000
          dt - Data Test Program                              Version 13.22



          4.13  Error Limit "errors=" Option.

               This option controls the maximum number of errors  tolerated
          before the program exits.

          Special Notes:
            o  The default error limit is 1.
            o  All errors have a time stamp associated with them, which may
               be useful for characterizing intermittent error conditions.
            o  The error limit is adjusted for read, write, or data compare
               failures.  This limit is not enforced when flushing data, or
               for certain AIO wait operations which  are  considered  non-
               fatal (perhaps this will change).
            o  A future release may support an "onerr=" option  to  control
               the  action  of  errors  (e.g.,  loop, ignore (continue), or
               exit).


              Syntax:
                  errors=value     The number of errors to tolerate.


          4.14  File Limit "files=" Option.

               This option controls the number of  tape  files  to  process
          with tape devices.

          Special Notes:
            o  During the write pass, a tape file  mark  is  written  after
               each  file.   After all files are written, 1 or 2 file marks
               will be written automatically by the tape  driver  when  the
               device is closed.
            o  During reads, each file is expected to be  terminated  by  a
               file  mark  and read() system calls are expected to return a
               value of 0 denoting the end of file.  When reading past  all
               tapes  files, an errno of ENOSPC is expected to flag the end
               of media condition.
            o  Writing tape file marks is currently not  supported  on  the
               QNX Operating System.  The release I currently have does not
               support the mtio commands, and unfortunately the POSIX stan-
               dard  does  not  define  this  interface (the mtio interface
               appears to be a  UNIX  specific  standard).   Multiple  tape
               files can still be read on QNX systems however.


              Syntax:
                  files=value      Set number of tape files to process.







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