Hi Ahmad,
Increasing tRCD and tRP will essentially make it more costly to open and close
a page. If you have good page hit-rate, and good distribution over the banks,
then the effects of the increased timings can be hidden (at least from the
perspective of the average latency). When you increase tCL you are delaying
every single access.
bytesPerActivate is a histogram statistic associated with the DRAM controller.
You should find it in the stats.txt along with all the other stats.
Andreas
From: Ahmad Hassan via gem5-users
<[email protected]<mailto:[email protected]>>
Reply-To: Ahmad Hassan <[email protected]<mailto:[email protected]>>,
gem5 users mailing list <[email protected]<mailto:[email protected]>>
Date: Monday, 2 June 2014 10:29
To: gem5 users mailing list <[email protected]<mailto:[email protected]>>
Subject: [gem5-users] DDR timing model
Hi Andreas,
[Moving discussion from http://reviews.gem5.org/r/2109]
If I only increase the tCL parameter from 13.75ns to 61ns [4.4x times default
DDR3), then I notice 3.2x times increase in avgMemAccLat. This is what we
should expect. Can we use tCL to simulate slow DDR3? My understanding is that,
we cannot do that because tCL represents column address strobe and it affects
bandwidth.
But I cannot produce the same result by changing tRCD = '61ns', tRP = '165ns'.
tRCD affects read latency and tRP affects write latency. I only get an increase
in avgMemAccLat by 1.2x times default DDR3.
Results:
For default DDR3:
avgMemAccLat 22133.24
totMemAccLat 12166996811
For tRCD = '61ns', tRP = '165ns'.
avgMemAccLat 27473.08
totMemAccLat 15104591550
For tCL = '61ns'
avgMemAccLat 71630.94
totMemAccLat 39376746052
I did not find any 'bytesPerActive' attribute in stats file. Where shall I see
this?
Thanks.
-- 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
[email protected]
http://m5sim.org/cgi-bin/mailman/listinfo/gem5-users
