Difference between revisions of "Session:Making RCU Safe For Battery-Powered Devices ELC2012"

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(Created page with "== Session Details == ; Event : Embedded Linux Conference 2012 ; Date : February 16, 2012 ; Presenter : Paul E. McKenney ; Organization: IBM ; Slides : http://elinux.org/imag...")
 
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=== Abstract ===
 
=== Abstract ===
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Back in the 1990s, energy efficiency was not even on the list of RCU-related concerns. Systems using RCU at that time dealt with either large quantities of heavy equipment or large financial flows, so that the energy consumption of the entire server (let alone RCU's contribution) was way down in the noise. This situation changed dramatically with the 2002 introduction of RCU into the Linux kernel. Since then, RCU's energy-efficiency code has been rewritten more than five times. The most recent rewrite was motivated by workloads where RCU was leaving tens of percent of potential energy savings on the table. This talk will give a brief overview of how energy efficiency came to RCU, the current situation, future prospects, and generally applicable lessons learned.
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=== Biography ===
 
=== Biography ===
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Paul E. McKenney is a Distinguished Engineer with the IBM Linux Technology Center, where he maintains the RCU implementation within the Linux kernel. He has been coding for almost four decades, and more than half of that on parallel hardware. His prior lives include working on the DYNIX/ptx kernel at Sequent, work on packet radio, Internet protocols, and system administration at SRI International, and work on soft-realtime systems as a self-employed contract programmer. His hobbies include what passes for running at his age along with the usual house-wife-and-kids habit.
  
 
=== Notes ===
 
=== Notes ===
  
 
== Transcript ==
 
== Transcript ==
; Transcribed by:  
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; Transcribed by: Arnout Vandecappelle
 
; Verified by: 1 -  
 
; Verified by: 1 -  
  
0:00 - 1:00:
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0:00 - 1:00: [some pre-presentation chatting] >> PAUL MCKENNEY: [slide 1 - title] I'm going to go through a little obligatory what-is-RCU. At my age, you ''have'' to have at least some slide about "The Good Old Days", as a log [?] or something, and something about that. We'll take a look at RCU's many energy-efficiency variants over the years, the current state of its energy-efficiency, and of course future directions.
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[slide 2 - What is RCU?] Now how many people here have actually written code that uses RCU? Good, we got some, great! Now how many people have ever viewed code that has calls to RCU in it?
  
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1:00 - 2:00: Okay, a few more, good. How many people have heard of RCU before today? All right, that's good. Not so long ago [?] I wouldn't have seen any hands for that last one either. [remark from the audience] Yes, there was a time when I could have said yes to the first one and no to the last one, but that was long ago. Anyway. OK, let's go through it quickly. This is just a taste of it. I'll just take a few minutes to go through it. I have a slide at the end of this section that has a list of places to go to get more information.
  
 
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Revision as of 17:28, 6 November 2012

Session Details

Event 
Embedded Linux Conference 2012
Date 
February 16, 2012
Presenter 
Paul E. McKenney
Organization
IBM
Slides 
http://elinux.org/images/0/06/Making_RCU_Safe_For_Battery-Powered_Devices.pdf
Video 
Free Electrons (450x800) or Free Electrons (Full HD) or Linux Foundation
Duration 
52:29

Abstract

Back in the 1990s, energy efficiency was not even on the list of RCU-related concerns. Systems using RCU at that time dealt with either large quantities of heavy equipment or large financial flows, so that the energy consumption of the entire server (let alone RCU's contribution) was way down in the noise. This situation changed dramatically with the 2002 introduction of RCU into the Linux kernel. Since then, RCU's energy-efficiency code has been rewritten more than five times. The most recent rewrite was motivated by workloads where RCU was leaving tens of percent of potential energy savings on the table. This talk will give a brief overview of how energy efficiency came to RCU, the current situation, future prospects, and generally applicable lessons learned.

Biography

Paul E. McKenney is a Distinguished Engineer with the IBM Linux Technology Center, where he maintains the RCU implementation within the Linux kernel. He has been coding for almost four decades, and more than half of that on parallel hardware. His prior lives include working on the DYNIX/ptx kernel at Sequent, work on packet radio, Internet protocols, and system administration at SRI International, and work on soft-realtime systems as a self-employed contract programmer. His hobbies include what passes for running at his age along with the usual house-wife-and-kids habit.

Notes

Transcript

Transcribed by
Arnout Vandecappelle
Verified by
1 -

0:00 - 1:00: [some pre-presentation chatting] >> PAUL MCKENNEY: [slide 1 - title] I'm going to go through a little obligatory what-is-RCU. At my age, you have to have at least some slide about "The Good Old Days", as a log [?] or something, and something about that. We'll take a look at RCU's many energy-efficiency variants over the years, the current state of its energy-efficiency, and of course future directions.

[slide 2 - What is RCU?] Now how many people here have actually written code that uses RCU? Good, we got some, great! Now how many people have ever viewed code that has calls to RCU in it?

1:00 - 2:00: Okay, a few more, good. How many people have heard of RCU before today? All right, that's good. Not so long ago [?] I wouldn't have seen any hands for that last one either. [remark from the audience] Yes, there was a time when I could have said yes to the first one and no to the last one, but that was long ago. Anyway. OK, let's go through it quickly. This is just a taste of it. I'll just take a few minutes to go through it. I have a slide at the end of this section that has a list of places to go to get more information.

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