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TLB(8)                              LMBENCH                             TLB(8)

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)