Locality Group Library Functions              lgrplatency(3LGRP)



NAME
     lgrplatency, lgrplatencycookie - get latency between  two
     lgroups

SYNOPSIS
     cc [ flag... ] file... -llgrp [ library... ]
     #include 

     int lgrplatencycookie(lgrpcookiet cookie, lgrpidt from,
          lgrpidt to, lgrplatbetweent between);


     int lgrplatency(lgrpidt from, lgrpidt to);


DESCRIPTION
     The lgrplatencycookie() function takes a cookie represent-
     ing  a  snapshot  of  the  lgroup  hierarchy  obtained  from
     lgrpinit(3LGRP) and returns the  latency  value  between  a
     hardware  resource in the from lgroup to a hardware resource
     in the to lgroup. If from is the  same  lgroup  as  to,  the
     latency value within that lgroup is returned.


     The between argument should be set to the following value to
     specify  between which hardware resources the latency should
     be measured:

       LGRPLATCPUTOMEM     /* latency from CPU to memory */



     The latency value is defined by the operating system and  is
     platform-specific.  It  can  be  used only for relative com-
     parison of lgroups on the running system. It does not neces-
     sarily  represent  the  actual latency between hardware dev-
     ices, and it might not be applicable across platforms.


     The   lgrplatency()   function   is   similiar    to    the
     lgrplatencycookie()  function,  but  returns  the  latency
     between the given lgroups at  the  given  instant  in  time.
     Since  lgroups  can  be freed and reallocated, this function
     might not be able to  provide  a  consistent  answer  across
     calls.  For  that reason, the lgrplatencycookie() function
     should be used in its place.

RETURN VALUES
     Upon successful completion, the latency value  is  returned.
     Otherwise  -1  is  returned and errno is set to indicate the
     error.




SunOS 5.11          Last change: 26 Jan 2005                    1






Locality Group Library Functions              lgrplatency(3LGRP)



ERORS
     The lgrplatencycookie() and lgrplatency() functions  will
     fail if:

     EINVAL    The specified cookie, lgroup ID,  or  value  given
               for the between argument is not valid.


     ESRCH     The specified lgroup ID was not  found,  the  from
               lgroup does not contain any CPUs, or the to lgroup
               does not have any memory.


ATRIBUTES
     See attributes(5) for descriptions of the  following  attri-
     butes:



     
           ATRIBUTE TYPE               ATRIBUTE VALUE       
    
     Interface Stability          Evolving                    
    
     MT-Level                     MT-Safe                     
    


SEE ALSO
     lgrpinit(3LGRP), lgrpparents(3LGRP), lgrpchildren(3LGRP),
     liblgrp(3LIB), attributes(5)
























SunOS 5.11          Last change: 26 Jan 2005                    2