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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.   Assum-
     ing  there  is a fixed size TLB, then at some point the number of pages ac-
     cessed 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 sys-
     tems.  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)

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