Re: [Linux-ia64] VHPT performance

[David Mosberger <davidm@napali.hpl.hp.com>]

>>>>> On Fri, 08 Mar 2002 11:26:33 +0100, Christian Hildner <christian.hildner@hob.de> said:

  Christian> Ok that's true. I changed my program so that before the
  Christian> measuring loop there comes the same loop for filling the
  Christian> cache. Also I had to increase the memory size to a
  Christian> minimum of 128 pages because for itanium there are 32
  Christian> entries for L1-DTLB and 96 entries for L2-DTLB. Now I get
  Christian> values of 42 cycles with VHPT enabled and 180 cycles with
  Christian> VHPT disabled. This values are coming near to the ones
  Christian> you found.

Great!

Two other things you may want to try:

 o Use a stride of PAGE_SIZE+LINE_SIZE.  This reduces the likelihood
   of exceeding the cache associativity.

 o Rather than calling printf() in each iteration, collect the results
   in an array and print them once the test is done.  printf() is a monster
   and will blow away a good portion of the first level caches as well as
   a couple of TLB entries.

	--david