Re: [Gems-users] Dynamic link latency change in FILE_SPECIFIEDtopology

["Arseniy Vitkovskiy" <arseniy.vitkovskiy@xxxxxxxxx>]

Since there is no solution yet, I invite those who are interested in
this task and are eager to share their knowledge and ideas to
participate in this discussion.

I see a possible way to create this mechanism as follows:

1. In the topology specification file instead of writing only link
latency value, a time-and-latency pair should be stated for each link.
The time in cycles would refer to the moment when link latency must be
updated, e.g.

...
int_node:0 int_node:1 time: 0 link_latency:1 time: 100000 link_latency:
3 link_weight:1
...

2. Then all these pairs are written in array in a timeline manner in
order to schedule the update events.

3. The first difficulty may appear if link_latency must be updated while
a flit is in flight in this link. Here I see two solutions:

a) A solution that seems to be easier to implement. If link buffer is
occupied with a flit we reschedule the link_latency update time for a
later moment when the link buffer is released. 
b) More difficult solution would be to implement a retransmission scheme
which would require an output buffer with depth not smaller than max
link_latency.

4. During the latency update event, first SIMICS must be paused (what is
the mechanism to pause SIMICS?), then all events in GEMS must be frozen
(this probably can be done with scheduling?). After that the
link_latency table (maybe also routing table) is updated and simulator
returns to its normal functionality with the updated link_latency
values.

If somebody has any remarks, suggestions or advices please post them in
this thread.


Kind regards,
Arseniy.
 
> -----Original Message-----
> From: gems-users-bounces@xxxxxxxxxxx [mailto:gems-users-
> bounces@xxxxxxxxxxx] On Behalf Of Dan Gibson
> Sent: Monday, July 05, 2010 6:19 PM
> To: Gems Users
> Subject: Re: [Gems-users] Dynamic link latency change in
> FILE_SPECIFIEDtopology
> 
> Sorry -- there is no mechanism to dynamically adjust the latencies of
> links. Feel free to make one yourself... those of us that know that
code
> (not me) may be helpful if you give us specific questions.
> 
> Regards,
> Dan
> 
> 
> On Mon, Jul 5, 2010 at 10:06 AM, Arseniy Vitkovskiy
> <arseniy.vitkovskiy@xxxxxxxxx> wrote:
> 
> 
> 	Can anybody help regarding the above question?
> 
> 	Kind regards,
> 	Arseniy.
> 
> 
> 
> 	> -----Original Message-----
> 	> From: gems-users-bounces@xxxxxxxxxxx [mailto:gems-users-
> 	> bounces@xxxxxxxxxxx] On Behalf Of Arseniy Vitkovskiy
> 	> Sent: Friday, June 25, 2010 5:40 PM
> 	> To: gems-users@xxxxxxxxxxx
> 	> Subject: [Gems-users] Dynamic link latency change in
> FILE_SPECIFIED
> 	> topology
> 	>
> 	> Hi all,
> 	>
> 	> is there any possibility to dynamically adjust network link
> latencies
> 	in
> 	> Garnet for FILE_SPECIFIED topology? Is it also possible to cut
off
> 	network
> 	> links dynamically? I would be very appreciate for any help
with
> this.
> 	>
> 	> Kind regards,
> 	> Arseniy.
> 
> 
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