Finally gotten around to ordering an extra 64GB of RAM. I have ordered PC3200 RAM while the 32GB I have is PC2800. Will I be better off ditching the old and just running with 64GB to take advantage of the slightly higher speed or keeping it to have 96GB total?

Main reason for upgrading is to increase the maximum number of OIFS tasks I can run at once.

My guess is that it really depends on how many cores your processor has and therefore how many tasks it can run at any one time. I am not sure that having differeent speed memory chips makes much difference to perforamnce.

My guess is that it really depends on how many cores your processor has and therefore how many tasks it can run at any one time. I am not sure that having differeent speed memory chips makes much difference to perforamnce.

It also depends on how big the cache on the processor chip(s) is.

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My guess is that it really depends on how many cores your processor has and therefore how many tasks it can run at any one time.

AMD Ryzen 7 3700X 8-Core Processor [Family 23 Model 113 Stepping 0] When it arrives, I might try with just the 64GB of faster ram and then tweak the motherboard settings to take advantage of it. I never to run more than 7 tasks at a time so that still leaves a reasonable bit of headroom. If I don't see any improvement, I might put the other 32 back in and have a ram disk.

The CPDN tasks seem to really hammer on memory, so I'd expect, if it's sufficient to run the task quantities your chip can reasonably support, "less faster memory" would be better than "more slower memory."

The CPDN tasks seem to really hammer on memory, so I'd expect, if it's sufficient to run the task quantities your chip can reasonably support, "less faster memory" would be better than "more slower memory."

I think 64GB for an 8 core CPU is probably sufficient. Some tasks in testing have gone up above 9GB peak per task recently but they have the BOINC debugging code enabled which adds a lot to the overhead. If at some point the demand goes up even more, I can either go up to the max on the motherboard of 128GB or run fewer tasks. Currently I am running one of the memory intensive tasks and six WAH2ri tasks and free tells me that swap is unused. I do wonder if once I double my RAM I could get rid of swap altogether?

The CPDN tasks seem to really hammer on memory, so I'd expect, if it's sufficient to run the task quantities your chip can reasonably support, "less faster memory" would be better than "more slower memory."

I think 64GB for an 8 core CPU is probably sufficient. Some tasks in testing have gone up above 9GB peak per task recently but they have the BOINC debugging code enabled which adds a lot to the overhead. If at some point the demand goes up even more, I can either go up to the max on the motherboard of 128GB or run fewer tasks. Currently I am running one of the memory intensive tasks and six WAH2ri tasks and free tells me that swap is unused. I do wonder if once I double my RAM I could get rid of swap altogether?

In the very old days, it was recommended to have twice as much disk space for swap as the machine had RAM. Later, as RAM cost less and people put more and more RAM in their machines, this recommended amount was reduced to the same amount of swap as RAM. But RAM has gotten so large that I run my current machine with the same amount od swap as it had when I bought it. It had 32 GBytes of RAM when I bought it. though it has 128 GBytes now. It runs Linux. It has been running 24/7 for about a week and has used about 15 Megabytes of RAM: not much. It is running 11 Boinc processes at the moment.

$ free -hw
              total        used        free      shared     buffers       cache   available
Mem:          125Gi       6.1Gi       1.7Gi       1.5Gi       764Mi       116Gi       116Gi
Swap:          15Gi        15Mi        15Gi

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The decision turns out to be academic. The old Corsair memory is fat enough that it won't fit in the slots alongside the new memory. However if I ever decide 64GB is not enough two more of the crucial modules I just bought will fit enabling me to double again.

I do wonder if once I double my RAM I could get rid of swap altogether?

Probably not a good idea to get rid of the swap file. The OS behaviour would be unpredictable.

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I do wonder if once I double my RAM I could get rid of swap altogether?

Probably not a good idea to get rid of the swap file. The OS behaviour would be unpredictable.

Perhaps though swap hasn't been touched since I did the upgrade. I might look at substantially reducing the size from the current 64GB the next time I do a reinstall from scratch. Though that might be a while!

Perhaps though swap hasn't been touched since I did the upgrade. I might look at substantially reducing the size from the current 64GB the next time I do a reinstall from scratch. Though that might be a while!

I would keep a swap file. My machine has a swap file that is 16 GBytes and it is using 1/4 GByte of swap. If I boot the machine, it goes a couple of days without using any swap, but it slowly goes up a little bit. It happens when I am asleep, so it probably has something to do with writing backups to external hard drive. Machine mostly runs Boinc 24/7, but I do some other things during the day. It has done no CPDN since about last June because there is no Linux work from CPDN.

My machine has 128 GBytes of RAM, yet, in time, I use a little swap. This machine has been up almost two weeks and it has used a trifle of swap.

top - 07:32:33 up 13 days, 21:41,  2 users,  load average: 13.37, 13.58, 13.40
Tasks: 476 total,  17 running, 459 sleeping,   0 stopped,   0 zombie
%Cpu(s):  0.6 us,  0.3 sy, 80.6 ni, 18.3 id,  0.0 wa,  0.2 hi,  0.0 si,  0.0 st
MiB Mem : 128074.0 total,   1635.3 free,   6490.1 used, 119948.7 buff/cache
MiB Swap:  15992.0 total,  15717.7 free,    274.2 used. 117948.7 avail Mem 

$ free -hw
              total        used        free      shared     buffers       cache   available
Mem:          125Gi       6.3Gi       1.6Gi       2.4Gi       1.1Gi       116Gi       115Gi
Swap:          15Gi       274Mi        15Gi

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A practical reason to have swap these days is if you intend using 'hibernate', which dumps the memory to swap space on the drive (i.e. configure swap to be 1.5x installed RAM). Otherwise, modern OSes work fine without swap as long as you have sufficient memory for what it is you intend to do with the machine.

A practical reason to have swap these days is if you intend using 'hibernate', which dumps the memory to swap space on the drive (i.e. configure swap to be 1.5x installed RAM).

I do not even know how to make my Linux machine hibernate. So I never do it.

As delivered, it had 32 GBytes of RAM and 16 Gbytes of swap. I upped the RAM to 128 GBytes, but saw no reason to increase the size of the swap area of my solid state drive. No reason to reduce it either. My Boinc data are on a partition of its own on a spinning 4 TByte hard drive, I cannot imagine having 192 GBytes of swap. Running two weeks 24/7, my machine is currently using 278.8 Megabytes of swap while running 13 Boinc tasks. That is hardly any.

Otherwise, modern OSes work fine without swap as long as you have sufficient memory for what it is you intend to do with the machine.

If It did not have swap space, where would the OS have put the 278.8 Megabytes of stuff?

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Probably not a good idea to get rid of the swap file. The OS behaviour would be unpredictable.

Any modern operating system runs just fine with no swapfile, and has for a couple decades now. Just don't run it out of RAM, unless you want the OOM reaper to show up.

If you are running on Windows, TThrottle is a tool you can use to scale your BOINC computation on the fly to hold a specified CPU temperature. I make use of it on all my Windows machines, particularly my laptop which gets quite toasty if I let it run at 100% unchecked.

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