Re: [Gems-users] logTM conflict resolution

[Jayaram Bobba <bobba@xxxxxxxxxxx>]

$GEMS/ruby/log_tm/TransactionConflictManager.C gives a more precise 
description of the conflict resolution policies
than the wiki.

The conflict resolution policies used in the pathologies paper:
EE - BASE and HYBRID
EL - BASE and TIMESTAMP
LL - BASE

The XACT_NO_BACKOFF parameter determines if software backoff is used 
along with any particular policy. Look at
gen-scripts.py to see which policies use this parameter.

Jayaram


Jim Leek wrote:
> In the Pathologies paper it gives a set of the different kinds of 
> Transactional memory styles, and they have different conflict 
> resolution methods.  LL is committer wins, EL is Requester wins, and 
> EE is requester stalls.  However, I don't really see these options in 
> rubyconfig.defaults.  This is what the wiki says:
> *XACT_EAGER_CD*: (true or false) Setting to true enables eager 
> conflict detection. Otherwise uses lazy conflict detection.
> *XACT_LAZY_VM*: (true or false) Setting to true enables lazy version 
> management via an infinite write buffer. Otherwise uses eager version 
> management. *Must also set XACT_MEMORY to true during protocol 
> compilation, or else appropriate Simics callbacks will not get registered.
> **XACT_CONFLICT_RES*: (BASE, TIMESTAMP, HYBRID, or CYCLE) Different 
> policies of conflict resolution. BASE aborts the requestor whenever 
> there's a conflict. TIMESTAMP aborts a requestor only if the requestor 
> is younger than the conflicting processor. HYBRID aborts a younger 
> transaction in favor of an older requesting transaction if the younger 
> has the conflicting block in its read set only. CYCLE always indicates 
> a conflict with other transactions, and is used to immediately trap to 
> a software contention manager.
> so, if I use EE-base, does requester stall? EL's policy of requester 
> always wins doesn't even seem to be an option?  (I'm guessing that 
> EL-base actually does this.)
> Thanks,
> Jim
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