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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 jump-
     ing  to the next page).  It measures the average memory latency for a vari-
     ety 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  la-
     tency  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 ex-
     pensive 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  sys-
     tems.

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)

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