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)