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buzzword [2015/03/25 18:19]
rachata
buzzword [2015/03/27 18:24]
rachata
Line 948: Line 948:
  
  
 +===== Lecture 23 (03/27 Fri.) =====
 +
 +  * Different ways to control interference in DRAM
 +    * Partitioning of resource
 +      * Channel partitioning:​ map applications that interfere with each other in a different channel
 +        * Keep track of application'​s characteristics
 +        * Dedicate a channel might waste the bandwidth
 +        * Need OS support to determine the channel bits
 +    * Source throttling
 +      * A controller throttle the core depends on the performance target
 +      * Example: Fairness via source throttling
 +        * Detect unfairness and throttle application that is interfering
 +        * How do you estimate slowdown?
 +        * Threshold based solution: hard to configure
 +    * App/thread scheduling
 +      * Critical threads usually stall the progress
 +    * Designing DRAM controller
 +      * Has to handle the normal DRAM operations
 +        * Read/​write/​refresh/​all the timing constraints
 +      * Keep track of resources
 +      * Assign priorities to different requests
 +      * Manage requests to banks
 +    * Self-optimizing controller
 +      * Use machine learning to improve DRAM controller
 +    * A-DRM
 +      * Architecture aware DRAM
 +  * Multithread
 +    * synchronization
 +    * Pipeline programs
 +      * Producer consumer model
 +    * Critical path
 +    * Limiter threads
 +    * Prioritization between threads
 +  * Different power mode in DRAM
 +  * DRAM Refresh
 +    * Why does DRAM has to refresh every 64ms
 +    * Banks are unavailable during refresh
 +      * LPDDR mitigate this by using a per-bank refresh
 +    * Has to spend longer time with bigger DRAM
 +    * Distributed refresh: stagger refresh every 64 ms in a distributed manner
 +      * As oppose to burst refresh (long pause time)
 +  * RAIDR: Reduce DRAM refresh by profiling and binning
 +    * Some row do not have to be refresh very frequently
 +      * Profile the row
 +        * High temperature changes the retention time: need online profiling
 +  * Bloom filter
 +    * Represent set membership
 +    * Approximated
 +    * Can contain false positive
 +      * Better/more hash function helps eliminate this
   ​   ​
 +
buzzword.txt ยท Last modified: 2015/04/27 18:20 by rachata