NAME

       memtier - redirect malloc calls to memkind memory tiering

SYNOPSIS

       memtier [ -r ratio ] [ -t thresholds ] program args...

DESCRIPTION

       memtier  runs  the given program, redirecting memory allocations to different memory tiers
       based on a given policy.  This allows unmodified programs to run  following  a  non-greedy
       allocation scheme that avoids a performance cliff when DRAM is exhausted.

OPTIONS

       -r ratio
              Specifies  the  ratio  as  a pair of integers separated by a colon, where the first
              number gives the relative share of near DRAM to be used  while  the  second  number
              gives  "far"  memory,  be  it  CXL  memory  or  PMEM.  Eg.  "1:4" means that 20% of
              allocations will use DRAM, 80% PMEM.

              If the ratio is not  given,  it  defaults  to  the  relative  share  of  physically
              installed memory.

              This version of memtier recognizes only two tiers (DRAM and KMEM_DAX).

       -t thresholds
              Turns  on  DYNAMIC_THRESHOLD  mode where small allocations are served from DRAM and
              large ones from far memory.  The syntax is described in depth  in  man  libmemtier,
              eg.   -t  INIT_VAL=1024,MIN_VAL=512,MAX_VAL=65536  starts with a threshold of 1024,
              then varies it between 512..65536 attempting to match the requested ratio.

       -v     Displays settings that are passed to libmemtier.

       -h     Shows a help message then exits.

CAVEATS

       This tool doesn't expose all features of libmemtier.  Only DRAM  and  KMEM_DAX  memory  is
       supported,  to  use FS_DAX you need to configure the library directly, please refer to its
       man page.

       Or alternatively, you can switch that memory to KMEM_DAX mode.  For that  purpose,  please
       refer to "man ndctl-reconfigure-namespace" and "man daxctl-reconfigure-device".

SEE ALSO

       libmemtier(7), memkind(3), malloc(3)