NAME

       tlb - TLB size and latency benchmark

SYNOPSIS

       tlb [ -L <line size> ] [ -M <len> ] [ -W <warmups> ] [ -N <repetitions> ]

DESCRIPTION

       tlb  tries  to  determine the size, in pages, of the TLB.  The largest amount of memory it
       will examine is len bytes.

       tlb compares the memory latency for two different pointer chains.  The two  chains  occupy
       the  same  amount  of  cache space, but they stress the memory subsystem differently.  The
       first chain accesses one word per page, while the second chain randomly jumps through  all
       the  lines  on a page before jumping to the next page.  When all of the pointers reside in
       the cache (which is the usual case), and all of the pages for the first  chain  reside  in
       the TLB, then the average memory latencies should be identical.  Assuming there is a fixed
       size TLB, then at some point the number of pages accessed by the first page will be larger
       than  the  TLB.   At  this  point the average latency for each memory access for the first
       chain will be a cache hit plus some fraction of a TLB miss.

       Once the TLB boundary is located tlb reports the TLB miss latency as the TLB  latency  for
       twice as many pages as the TLB can hold.

BUGS

       tlb  is an experimental benchmark, but it seems to work well on most systems.  However, if
       a processor has a TLB hierarchy tlb only finds the top level TLB.

SEE ALSO

       lmbench(8), line(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          $Date$                                       TLB(8)