Lecture 21: Main Memory and the DRAM System - Carnegie Mellon - Comp. Arch. 2015 - Onur Mutlu

[@tvcharan]

Amazing Lectures!!! Thank you for making it public. Hope some day will listen to your live lecture and Interact with you

[@thyagtubes]

Lecture starts at 9:04

[@ilyasgaripov3686]

Very helpful, thank you

[@calengr1]

main memory starts at 7 40

[@ankitvashishtha7410]

Hi Prof. Onur Mutlu, All the facts beautifully explained. Hats Off! Thanks for the lectures. Now, I have two doubts, first how memory controller is selecting the rank no. from given address? You have shown only row, channel. & column selection from a coming address) ( Time : 1:19:22 - kzbin.info/www/bejne/f4bOaqJvrNuLZ7s ) Second doubt: Do you have any video explaining the Memory Controller & PHY interconnection with working with DRAM Chip. How different timing signals like DQS etc work together? If yes please share the link.

[@noahgoldstein3951]

If you pipeline subarray access in banks won't you essentially end up thrashing the global row-buffer? Seems like this will increase the frequency of precharging (and then power consumption AFAICT).

[@PrinceKumar-bi6vq]

In THREAD CLUSTERING MEMORY SCHEDULING My doubts are - 1. Which threads are you refering here ? Is it hardware thread or kernel/user thread? 2. How does memory controller gets the information related to thread?

[@CMUCompArch]

1. It is hardware threads. More specifically, hardware context ID. 2. The hardware context ID is communicated with each request to the memory controller. I would suggest reading earlier works on the topic of thread-aware memory scheduling, which cover such information in more detail: Mutlu and Moscibroda, "Stall-Time Fair Memory Access Scheduling for Chip Multiprocessors", MICRO 2007. people.inf.ethz.ch/omutlu/pub/stfm_micro07.pdf Mutlu and Moscibroda, "Parallelism-Aware Batch Scheduling: Enhancing both Performance and Fairness of Shared DRAM Systems", ISCA 2008. people.inf.ethz.ch/omutlu/pub/parbs_isca08.pdf

[@lebanbo55]

I know.

[@lebanbo55]

Why there are so many "@"?

[@hrqasim]

I don't get the point that each column gives 8 bits?? Column decoder is also a mux which selects one of the bits in row buffer??

[@sujayyadalam9842]

A single row buffer consists of multiple bytes. For example, you can have a DRAM with 8kB row buffers. The column decoder is used to select the block (again block size can be different, for example 64 bytes) in the row.

[@zaferesen1253]

I think in the images it is abstracted to show a single bit; but under the hood, the columns actually consist of 8 stacked memory cells (connected to the same row-column intersection).