[Info-vax] Poulson at hot-chips 2011

[Bob Koehler]

In article <4e53e514$0$30141$c3e8da3$9b4ff22a at news.astraweb.com>, JF Mezei <jfmezei.spamnot at vaxination.ca> writes:
> 
> I am puzzled by the "instruction replay".  They say it is to try
> instructions again if an error is detected.

   Instruction replay is essentially what a VAX uses when an instruction
   gets a page fault.  I suspect all virtual memory systems do something
   like it.

   Recovery from predictibly bad data is how old 1/2 inch tape drives
   got 6250 BPI net by actually recording about 9000 bits per inch.

   I was not aware of this technique being applied to cache errors, but
   if the resulting machine is faster than what can be done without the
   cache errors, I'm not really surprized.