By: Doug S (foo.delete@this.bar.bar), August 24, 2012 8:34 am
Room: Moderated Discussions
Linus Torvalds (torvalds.delete@this.linux-foundation.org) on August 22, 2012 10:16 am wrote:
> This is
> one of the reasons why I was arguing so strongly at one point (both here and to
> some Intel engineers) for the transaction model to use "success prediction"
> (possibly actually re-using the branch prediction hardware, but possibly with a
> separate predictor). Because part of "really cheap failure modes" is to not even
> bother trying if it's unlikely to work.
Wouldn't you want a combination of both hardware and software as the ideal? Same thing as the hints to branch prediction used in Linux - "if (unlikely(condition)) ..." There will be some transactions with little contention you feel would almost never fail, and vice versa.
> This is
> one of the reasons why I was arguing so strongly at one point (both here and to
> some Intel engineers) for the transaction model to use "success prediction"
> (possibly actually re-using the branch prediction hardware, but possibly with a
> separate predictor). Because part of "really cheap failure modes" is to not even
> bother trying if it's unlikely to work.
Wouldn't you want a combination of both hardware and software as the ideal? Same thing as the hints to branch prediction used in Linux - "if (unlikely(condition)) ..." There will be some transactions with little contention you feel would almost never fail, and vice versa.
Topic | Posted By | Date |
---|---|---|
Article: Haswell TM Alternatives | David Kanter | 2012/08/21 09:17 PM |
Article: Haswell TM Alternatives | Håkan Winbom | 2012/08/21 11:52 PM |
Article: Haswell TM Alternatives | David Kanter | 2012/08/22 01:06 AM |
Article: Haswell TM Alternatives | anon | 2012/08/22 08:46 AM |
Article: Haswell TM Alternatives | Linus Torvalds | 2012/08/22 09:16 AM |
Article: Haswell TM Alternatives | Doug S | 2012/08/24 08:34 AM |
AMD's ASF even more limited | Paul A. Clayton | 2012/08/22 09:20 AM |
AMD's ASF even more limited | Linus Torvalds | 2012/08/22 09:41 AM |
Compiler use of ll/sc? | Paul A. Clayton | 2012/08/28 09:28 AM |
Compiler use of ll/sc? | Linus Torvalds | 2012/09/08 12:58 PM |
Lock recognition? | Paul A. Clayton | 2012/09/10 01:17 PM |
Sorry, I was confused | Paul A. Clayton | 2012/09/13 10:56 AM |
Filter to detect store conflicts | Paul A. Clayton | 2012/08/22 09:19 AM |
Article: Haswell TM Alternatives | bakaneko | 2012/08/22 02:02 PM |
Article: Haswell TM Alternatives | David Kanter | 2012/08/22 02:45 PM |
Article: Haswell TM Alternatives | bakaneko | 2012/08/22 09:56 PM |
Cache line granularity? | Paul A. Clayton | 2012/08/28 09:28 AM |
Cache line granularity? | David Kanter | 2012/08/31 08:13 AM |
A looser definition might have advantages | Paul A. Clayton | 2012/09/01 06:29 AM |
Cache line granularity? | rwessel | 2012/08/31 07:54 PM |
Alpha load locked granularity | Paul A. Clayton | 2012/09/01 06:29 AM |
Alpha load locked granularity | anon | 2012/09/02 05:23 PM |
Alpha pages groups | Paul A. Clayton | 2012/09/03 04:16 AM |
An alternative implementation | Maynard Handley | 2012/11/20 09:52 PM |
An alternative implementation | bakaneko | 2012/11/21 05:52 AM |
Guarding unread values? | Paul A. Clayton | 2012/11/21 08:39 AM |
Guarding unread values? | bakaneko | 2012/11/21 11:25 AM |
TM granularity and versioning | Paul A. Clayton | 2012/11/21 08:27 AM |
TM granularity and versioning | Maynard Handley | 2012/11/21 10:52 AM |
Indeed, TM (and coherence) has devilish details (NT) | Paul A. Clayton | 2012/11/21 10:56 AM |