Hi Yuting, The short answer: for requests, no.
The long answer: You may have seen that I just pushed a patch that adds latency in the crossbar on the response path. In essence we just use a queued port to hold on to the packets until they are supposed to be sent. The reason it is challenging to do this on the request side is the assumptions in the gem5 coherency protocol. At the moment, the caches assume that once an Ln cache sends the message successfully, an Ln+1 cache is now owning the packet (and the associated MSHR if any). There is a possibility to be selective about what requests may be delayed in the crossbar, and what requests must pass the crossbar in zero time, but it is not straight forward to make the separation. Instead, what we do at the moment is to annotate a ‘debt’ on the packet, in the form of headerDelay and payloadDelay. Then, we expect a down-stream component to pay for this latency. In worst case we pay for it on the response side (see above), when the packet returns through the crossbar. Thus, the overall latency is growing as expected, we simply do not incur the wait for the request itself. I hope that brings some clarity to the matter. Andreas On 09/07/2015 06:21, "gem5-users on behalf of cao2" <gem5-users-boun...@gem5.org on behalf of c...@mail.usf.edu> wrote: >HI there > >I notice that the tick displayed membus receiving function and sending >function are the same, is there any way I can add a latency in between >for better tracing result? > >Regards, >Yuting >_______________________________________________ >gem5-users mailing list >gem5-users@gem5.org >http://m5sim.org/cgi-bin/mailman/listinfo/gem5-users -- IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you. ARM Limited, Registered office 110 Fulbourn Road, Cambridge CB1 9NJ, Registered in England & Wales, Company No: 2557590 ARM Holdings plc, Registered office 110 Fulbourn Road, Cambridge CB1 9NJ, Registered in England & Wales, Company No: 2548782 _______________________________________________ gem5-users mailing list gem5-users@gem5.org http://m5sim.org/cgi-bin/mailman/listinfo/gem5-users
