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Conference wrksys::alphastation

Title:Alpha Workstation Conference
Notice:See note 1.* for conference notices
Moderator:WRKSYS::HOUSE
Created:Wed Sep 07 1994
Last Modified:Fri Jun 06 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:1996
Total number of notes:9122

1884.0. "speed for AS 500/500 's cache" by ZPOVC::POHING () Thu Mar 06 1997 23:11

    Hi,
    
    My customer is going to benchmark his application on the AS 500/500
    tomorrow & he is asking me on the cache speed of the AS 500/500. Does
    anyone know the speed of the following cache level ? 
    Could someone pls help ?
    
    Thanxs in advance.
    
    Cache size on chip 		  8 KB I
    			 	  8 KB D
      			 	  96KB level 2
    Cache size on board		  8 MB
    
    Thanxs.
    
    Rgds,
    Poh Ing
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1884.1More notesWRKSYS::DISCHLERI don't wanna wait in vainFri Mar 07 1997 08:304
    	See wrksys::alphastation500 note 84
        or type DIR/TITLE=MEM   DIR/TITLE=CACHE
    
    			RJD
1884.282.1 in wrksys::alphastation500WRKSYS::DISCHLERI don't wanna wait in vainFri Mar 07 1997 10:101
    Also, note 82.1 is good - in wrksys::alphastation500
1884.3Those notes don't cover the on-chip caches.WIBBIN::NOYCEPulling weeds, pickin' stonesFri Mar 07 1997 11:0411
For the on-chip caches, the answer (in cycles) is the same for all EV5/EV56
systems:

8KB D - can read 2 64-bit values every cycle, or write 1 64-bit value.
        read latency is 2 cycles (issue load, wait, use result).
        (Thus for AS500/500, read bandwidth = 8 Gbytes/sec, latency = 4 nsec.)

96KB L2 - can read or write a 32-byte chunk every other cycle (so for
	  sequential access its bandwidth matches the D-cache).  Read
	  latency from load to use is *about* 10 cycles.  (Thus for AS500/500,
          read bandwidth = 8 GB/sec, latency = ~ 20nsec.)