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Observer
4,596 Views
Registered: ‎02-25-2016

## DRAM Speed effect on Compilation Time

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Hi,

I am going to configure a new PC for running Vivado Tools. My main considerations is the simulation speed (say 50%), and Synthesis* (say another 50%). I know that FPGA compilation needs high IPC count, DRAM capacity and MBs of LL Cache. However, I do not know how the DRAM speed is related to the compilation time.

Currently, I have to decide between 2400MHz and 3000MHz DDR4-DRAM speed values. The reason I am asking is due to the motherboard selection (I have already selected the DRAM model). Motherboard A supports 2400MHz max DRAM speed, motherboard B supports 3000MHz max DRAM speed. Motherboard B is 40% more expensive than A.

So, what is the compilation time reduction that I could probably notice if using the 3000MHz DRAM relative to the 2400MHz DRAM? Should it be 0% reduction? ~5% reduction? more? Does the motherboard B selection worths?

*= usually I do not use OOC mode.

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Teacher
6,754 Views
Registered: ‎03-31-2012

@psathas the memory speed also contributes to price of a system so it's not just the motherboard price. Suppose higher speed memory makes your system run 1% faster (underestimate maybe 2-3%). Calculate the amount of time you would save by not waiting over 3 years of use of this sytem and see if it saves you enough money by making you more productive. I bet you will find that even at 1% a couple hundred dollars extra over the lifetime of a system is worth it.

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3 Replies
Teacher
6,755 Views
Registered: ‎03-31-2012

@psathas the memory speed also contributes to price of a system so it's not just the motherboard price. Suppose higher speed memory makes your system run 1% faster (underestimate maybe 2-3%). Calculate the amount of time you would save by not waiting over 3 years of use of this sytem and see if it saves you enough money by making you more productive. I bet you will find that even at 1% a couple hundred dollars extra over the lifetime of a system is worth it.

- Please mark the Answer as "Accept as solution" if information provided is helpful.
Give Kudos to a post which you think is helpful and reply oriented.
Observer
4,358 Views
Registered: ‎02-25-2016

Hi muzaffer,

I think you are right. A system with an 1% more speed maybe worths the fast motherboard in terms of productivity over 3 years. So I have ordered the fast MB and I will check the difference.

I will make a test running the DRAM at different speeds and check the results. I will come back with the results when I have the system ready.

Thanks.

Observer
4,024 Views
Registered: ‎02-25-2016

Hi,

Just made 2 small tests regarding the compilation time versus DRAM speed.

Test1: Compile an example design project with MB using DDR4-2133MHz.

Test2: Compile an example design project with MB using DDR4-3000MHz.

Each test was initiated after a system reboot using Vivado 15.4 and Virtex-Ultrascale VCU108 Microblaze Example Design Project, and repeated 3 times (6 system reboots in total, 3 for the test1 and 3 for the test2).

Results:

test1: 292 seconds (average)

test2: 283 seconds (average)

System setup: i5-7600K, 16GB RAM, Ubuntu Linux 17.

Performance improvement for DDR4-3000MHz was ~3% relative to the DDR4-2133MHz.