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       ureadahead - Read files in advance during boot


       ureadahead [OPTIONS]...  [PACK]


       ureadahead  (uber-readahead)  is  used  during  boot  to  read files in
       advance of when they are needed such that they are already in the  page
       cache, improving boot performance.

       When started without any arguments, it checks for the existance and age
       of the default pack file /var/lib/ureadahead/pack, and if  not  present
       or  older  than a month, will discard it and retrace the boot sequence.
       The pack will then contain information about the  files  opened  during
       boot, and the blocks that were in memory at the completion of the boot.

       If the file exists and is newer than a month old, or an alternate  PACK
       path  is  given  on  the command-line, the files listed in the pack are
       opened and the blocks read into the page cache using  the  readahead(2)
       system call.

       Pack  files  are  automatically  optimised  for  Solid-State  Disks  or
       rotational Hard Drives, depending on which you have.


              May be used to report on ureadahead's operation.  In particular,
              this  causes  information  about the size of the pack file to be
              output when reading and a complete dump of the contents  of  the
              pack file after tracing.

              Places  ureadahead  into  the  background once the pack file has
              been read, or once tracing has been enabled.

              This is ignored when reading on rotational  hard  drives,  since
              it's important for performance reasons not to content with other
              processes for I/O.

              Discards all pack files and forces re-tracing.

              Normally when tracing, ureadahead will wait for a  TERM  or  INT
              signal  before  concluding  and  generating the pack file.  This
              option instead sets a timeout after which tracing is terminated.

       --dump Dump  the  contents  of  the  pack  file to standard output in a
              pretty format, does not trace or read the contents into  memory.

              Used with --dump to sort the output.

              The  default  is open, which is the order that the files will be
              opened.   path  sorts  by  path  name,  disk  sorts  by  on-disk
              location, and size sorts by the amount of data that will be read
              for that file.


       PACK need not be the filename of a pack, instead it may be the name  of
       a  mount point (or indeed any non-file within the filesystem), in which
       case the pack for that device is read instead.  This allows  ureadahead
       to  be called in the style ureadahead /usr for filesystems split across
       multiple devices.

       Pack  files  for  these   other   devices   are   also   stored   under
       /var/lib/ureadahead and are named mountpoint.pack

       When tracing, these will be automatically generated.




       Written by Scott James Remnant <>


       Report bugs at <>


       Copyright (C) 2009 Canonical Ltd.

       This is free software; see the source for copying conditions.  There is
       NO warranty; not even for MERCHANTABILITY or FITNESS FOR  A  PARTICULAR