NAME

       flashcache_setioctl - Set I/O behavior for special process in flashcache

DESCRIPTION

       The  flashcache_setioctl  command  can  be  used  to  set/remove a process from flashcache
       blacklist/whitelist, or clear flashcache blacklist/whitelist.

SYNOPSIS

       flashcache_setioctl (-c | -a | -r) (-b pid |-w pid) ssd_devname

OPTIONS

       -c     Clear blacklist/whitelist

       -a     Add to blacklist/whitelist

       -r     Remove from blacklist/whitelist

       -b     Operate on blacklist

       -w     Operate on whitelist

FLASHCACHE CACHE POLICY

       Flashcache  can  be  put  in  one  of  2  modes  -  Cache  Everything  or  Cache   Nothing
       (dev.flashcache.cache_all).  The defaults is to "cache everything".

       These 2 modes have a blacklist and a whitelist.

       The  tgid  (thread group id) for a group of pthreads can be used as a shorthand to tag all
       threads in an application.  The tgid for a pthread is returned by getpid() and the pid  of
       the individual thread is returned by gettid().

       The algorithm works as follows :

       In  "cache  everything"  mode,  1)  If  the  pid  of  the process issuing the IO is in the
       blacklist, do not cache the IO.  ELSE, 2) If the tgid is in  the  blacklist,  don't  cache
       this  IO.   UNLESS  3)  The  particular  pid is marked as an exception (and entered in the
       whitelist, which makes the IO cacheable).  4) Finally, even if IO is cacheable up to  this
       point, skip sequential IO if configured by the sysctl.

       Conversely, in "cache nothing" mode, 1) If the pid of the process issuing the IO is in the
       whitelist, cache the IO.  ELSE, 2) If the tgid is in the whitelist, cache this IO.  UNLESS
       3) The particular pid is marked as an exception (and entered in the blacklist, which makes
       the IO non-cacheable).  4) Anything whitelisted is cached,  regardless  of  sequential  or
       random IO.

SEE ALSO

       flashcache_create(8)

       README and other documents in /usr/share/doc/flashcache-utils

       The   flashcache   source   code   and   all   documentation   may   be   downloaded  from
       <https://github.com/facebook/flashcache/>.

AUTHORS

       Flashcache is developed by Mohan Srinivasan <mohan@fb.com>

       This man page was written by Liang Guo <guoliang@debian.org> for Debian GNU/Linux (but may
       be used by others).