Another dumb question...................RAM

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Profile George 254
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Message 1843031 - Posted: 19 Jan 2017, 13:57:44 UTC

Hi Guys
I have a nest of laptops and a tower unit giving 8,000 -16,000 credits a day. Some are exclusively SETI@home and others are shared with Einstein@home, Enigma & Rosetta. My main machine is an Acer Travelmate 5760 (2012) where I have put in the max RAM to 8 GB running Win7 with MS Office 2010.
None of the laptops is < 4 years old and has OSs from XP to Win10 with most having Win7. The Dell-based TU was made up for me to do BOINC stuff and is a few months old. This and the HP laptop have GPU cards as well, so they crunch > the others.
I bought them off eBay and put the maximum RAM in each laptop to get the best performance, but reading a thread yesterday told me that I need not have bothered? More RAM does not mean faster processing of BOINC stuff?
Could someone explain please? Have I wasted my money?
TIA
George
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Message 1843033 - Posted: 19 Jan 2017, 14:11:11 UTC

Windows 7 (64-bit) struggles when RAM is below 4GB, this is operating system "fact of life".
SETI does not require much RAM to run in, but if you are using GPUs then the Windows drivers MAY require an amount of RAM to mirror the GPUs into, this increases the amount you need.
As an example, last night I had a quick look at the system monitor on my one remaining Windows machine (running win 7 Pro, 64-bit), this has 16GB of RAM, two Nvidia GTX970 GPUs and an 8-core AMD processor, just sitting there doing nothing 4GB of RAM was committed, starting BOINC added about 100MB, and then when the 8 tasks loaded and kicked in this increased by about 400MB.
(Half an hour later the same PC, with BOINC shutdown, was struggling to load a CAD model into RAM, sitting at about 15GB in use, - I wish I could stick another 16GB in....)

I believe SETI has one of the lowest RAM demands, but others may wish to comment, but I dare say others can comment.
Bob Smith
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Message 1843040 - Posted: 19 Jan 2017, 15:34:12 UTC

I have a 16 core (32 threads) machine (dual E5-2670s) running 24 CPU threads and 9 GPU threads of SETI (it has 3 GTX980 cards), Win 7 Ultimate and Task Manager shows RAM usage of 5.5GB. A detailed look at the processes shows a little under 40MB per CPU process and about 110MB/GPU process, for a total of somewhat under 2GB for SETI (BOINC is using an additional 150MB or so). So RAM is really not that much of an issue; the machine has 32GB, but I could cut it to 16 or less with no problems if I wished...

My 2nd cruncher is running a Xeon X5650 in an X58 MB with 8 threads of CPU and 6 threads of GPU (dual GTX 1080s) and is using 2.7GB of 12GB of RAM.
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Message 1843097 - Posted: 19 Jan 2017, 20:53:07 UTC

There are some projects than use quite a lot of ram. There was one I was running that used ~4GB per task. Currently SETI@home the memory requirements are pretty low. Normally <50MB per task for CPU tasks. GPU tasks can use more, but that varies based on the specific app. I think 100-200MB per GPU tasks might be a good rule of thumb.

If the systems were using all of the RAM and doing a lot of disk thrashing then the increased memory will defiantly help.
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Message 1843138 - Posted: 20 Jan 2017, 2:38:50 UTC

Crunching Seti will not improve simply by adding RAM above and beyond the minimum needed to run it successfully.
However, the computer itself may be more stable and responsive with more RAM at it's fingertips.
It can cut down on disc paging, for example.
Pretty rare for a computer to complain about having too much RAM.
So, you probably have not wasted your money totally.
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Message 1843146 - Posted: 20 Jan 2017, 3:25:09 UTC

With the current memory and motherboard memory controller architectures, I think that 16 GB is the natural configuration point these days. Unless you are running server versions of motherboards or CPUs, the default seems to be dual channel memory controllers which leads to the most common 8GB X 2 memory stick configurations. The memory die packages are only getting bigger, more so with the Xpoint or 3D RAM architectures coming to market. Windows or Linux is usually quite happy with 16 GB of memory to play around with. I normally am under 4GB of main memory utilization with 2 GPU's in each computer. OTOH, I am seeing greater than 4GB memory utilization per GPU card with two tasks running concurrently and 2GB memory buffers allocated in app_config.xml.
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Message 1843478 - Posted: 21 Jan 2017, 10:22:04 UTC

Thank you all for the helpful replies
George
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Message boards : Number crunching : Another dumb question...................RAM


 
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