Well, actually I also reported this as a bug a few months ago. The difference
here is how two events with same priorities and scheduled time are put in the
queue. In current code, later arrived events would be put in front of other
events which have the same priorities and scheduled time, and this means some
later arrived events would get handled first. Under most circumstances this is
probably ok. But for other, it's not neccessarily appropriate. For example, for
an Icache of 1 latency cycle, an instruction-fetch would put a cache accessing
event on the queue. Supposely it shoud get handled and the instructions would
be returned in next cycle. But since a cpuTick event has a same priority and
the tickEvent for next cycle would be actually put in front of the cache
accesing event when it is scheduled later. So in next cycle, the tickEvent
would be handled first and it has to wait for the access to return yet. In this
way, the actual latency of the Icache becomes 2 cycles. For the same reason, I
also changed the following lines
if (head == NULL || event->when() < head->when() || (event->when() ==
head->when() && event->priority() <= head->priority()))
to
if (head == NULL || event->when() < head->when() || (event->when() ==
head->when() && event->priority() < head->priority()))
> Date: Tue, 13 May 2008 05:35:56 -0700> From: [EMAIL PROTECTED]> To:
> [email protected]> Subject: Re: [m5-users] a bug report> > The statements
> are equivalent. It is written the way it is because it> can fail after just
> one comparison. In the version that you've shown,> two comparisons must be
> made.> > Nate> > 2008/5/13 fractal218 <[EMAIL PROTECTED]>:> > Hi,> > Do you
> think the following program in function void EventQueue::insert(Event> >
> *event) is a bug?> >> > if (event->when() <= curr->when() && (event->when() <
> curr->when() ||> > event->priority() <= curr->priority()))> > break;> >> > I
> think it should be the following:> >> > if (event->when() < curr->when() ||
> (event->when() = curr->when() &&> > event->priority() <= curr->priority()))>
> > break;> >> >> > ________________________________> >> > 快来用音乐为奥运加油> >
> 得奥运会、演唱会门票> > _______________________________________________> > m5-users
> mailing list> > [email protected]> >
> http://m5sim.org/cgi-bin/mailman/listinfo/m5-users> >
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