DragonFly On-Line Manual Pages

LINE(8)                             LMBENCH                            LINE(8)

NAME
       line - cache line size

SYNOPSIS
       line [ -M <len> ] [ -W <warmups> ] [ -N <repetitions> ]

DESCRIPTION
       line tries to determine the cache line size in bytes of the largest
       cache which is smaller than len bytes.

       line creates pointer chains which access the first word on each cache
       line on a page (randomly meandering through all the lines in a page
       before jumping to the next page).  It measures the average memory
       latency for a variety of line sizes, starting with a line size of one
       word.  When it finds an increase in the average latency that is
       significantly larger than the latency for the smaller line size then it
       assumes that it has found the line size.

       This algorithm works because for line sizes less than the true line
       size, at least two line cache lines fit in the space of a true cache
       line.  Since that cache line will be accessed twice, the first access
       will cause an expensive cache miss, while the second access will be a
       cache hit.  Once the line cache line is equal to the true cache line
       size, then all accesses will cause cache misses.

BUGS
       line is an experimental benchmark, but it seems to work well on most
       systems.

SEE ALSO
       lmbench(8), tlb(8), cache(8), par_mem(8).

AUTHOR
       Carl Staelin and Larry McVoy

       Comments, suggestions, and bug reports are always welcome.

(c)2000 Carl Staelin and Larry McVoy
                                    $Date$                             LINE(8)