Re: [Gems-users] LogTM bug: no reset on overflow bit!

["Cong Wang" <jameswang99@xxxxxxxxx>]

Hi there:
    It seems that in both of these protocols, the overflow bit is
reset when a CacheRequestType:ABORT_XACT, or
CacheRequestType:COMMIT_XACT comes in. But the problem is that these
two CacheRequestType never come in because the transactions get
aborted or committed through magic calls which are handled by calling
abortTransaction and commitTransaction methods in the transaction
manager. This can be verified in $GEMS/ruby/simics/command.C file.
    So, to make the protocol works with overflowing transactions, one
has to modify the protocol to set, clear and check of overflow bit
using the relevant methods in transaction manager. Hopefully this gets
incorporated into the new release of GEMS.

Regards
James Wang


On 8/9/07, 郭锐 <timmyguo@xxxxxxxxxxxxxxxx> wrote:
> An extra note. There have already been 'Overflow' functions in the
> TransactionManger. But it's never called at all. Maybe forgotten by the
> authors?
> > -----Original Message-----
> > From: gems-users-bounces@xxxxxxxxxxx
> [mailto:gems-users-bounces@xxxxxxxxxxx]
> > On Behalf Of 郭锐
> > Sent: Thursday, August 09, 2007 11:27 AM
> > To: gems-users@xxxxxxxxxxx
> > Subject: [Gems-users] LogTM bug: no reset on overflow bit!
> >
> > I ran into a protocol problem recently, and find that the overflow bit
> > doesn't get cleared properly at transaction commit. This bug exists in
> both
> > of the MOESI and the MESI version of the LogTM protocol. The GEMS version
> I
> > use is v1.4.
> >
> > A possible fix to this bug is just move the overflow bit from the cache
> > controller to the TransactionManager. Because there is no special cache
> > request to cache controller whenever a transaction is to be committed.
> >
> > G.R.
> >
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-- 
Regards
James Wang