Switching to RAM compilation and some hardware issues?

pmam · Veteran Joined: 30 Dec 2013 Posts: 1145

I just replaced my RAM memory from 2G to 4X4G, and want to use it for the compilation process (system updating etc).
Looks it is working ok but before start using it I want to verify if it is properly installed and suitable to my machine. Here output of free:

erikm · l33t Joined: 08 Feb 2005 Posts: 634

I don't know your motherboard, so I can't help you there. I can however confirm that the line in /etc/fstab is all you need for compiling in RAM.

pmam · Veteran Joined: 30 Dec 2013 Posts: 1145

erikm Hi,

I have put in my previous post the relevant part of my motherboard spec - if it is not enough here the link:
https://us.msi.com/Motherboard/support/G41M-P33-Combo.html#down-manual

Thanks for confirmation regarding fstab!
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krinn · Watchman Joined: 02 May 2003 Posts: 7470

8171628... try free -h to get the picture

because for me 4x4G should gave u twice that number.
it's not because a m/b have 4 banks that you can fill up all the banks with any size memory. Some will allow all 4 filled with 4G, some only with 4x2G...
and some will refuse or work bad with 4x4G from serie X and will nicely work with 4x4G from Z (even when Z and X are in fact from the same manufacturer).

you should had check memory compatibilities before buying, specially for high speed memory usage as most m/b makers are always offering a higher speed than usual. If a chip is given to do 1200mhz, they will offer 1300... if it could do 2000 they will offer some 2133mhz...
but that's not safe or usual speed for that chip, and they do that with tweaks, and in fact the highest speed they offer that is beyond what your chip "should" handle is then tricky as hell to make it work.

From your manual:
2 DD R2 667/800/1066(OC) DIMM slots (8GB Max)
2 DD R3 800/1066/1333 (OC) DIMM slots (8GB Max)
It explains first your 8G limit, but it also show that 1066 and 1333 are set OC (certainly meaning Overclock), as such it mean "tricky to work at that speed".
Also because of the 2xDDR2 and 2xDDR3 reference and the "combo" type of m/b you have, pretty sure the combo doesn't mean you can use 4 banks at the same time, but only 2xDDR2 or 2xDDR3.
Which raise another question, how did you get 2xDDR2 and 2xDDR3 and didn't ask yourself something wrong is going on. I suppose you have in fact brough 2x4G ram?

That's all i could say from that manual, i'm afraid i was going to much with the babes instead of my Chinese lessons.

Your FSB is set by your cpu: cpu_multiplier_ factor * fsb = cpu speed, so m/b handle the FSB you need base on your cpu. You can however overclock fsb to push your cpu overclock. a 20 * 100 = 2000mhz, while the same cpu at 133 fsb would gave you a 2660mhz cpu.

pmam · Veteran Joined: 30 Dec 2013 Posts: 1145

krinn,

Sorry, my fault...

I meant 2X4G (not 4X4G)...

Here:

krinn · Watchman Joined: 02 May 2003 Posts: 7470

if you really care about the clock speed, try lshw (in portage) it certainly can tell you.

NeddySeagoon · Posted: Tue Aug 09, 2016 4:21 pm Post subject:

pmam,

DRAM sticks, all flavours, contain a small chip called the SPD ROM.

This is read by the system to discover all sorts of useful information about the RAM. Including the default timings.
Some RAM sold as tested overclocked my have the overclocked timings progarmmed into the SPD.

This SPD being used for system set up leads to a whole class of hardware problems when RAM is not a single matched set.

-- edit --

The kernel will keep everything in RAM buffers during compiling, so if you have the RAM to build in RAM if will happen anyway and you see the speed improvement
Mounting /var/tmp/partage as tmpfs does not provide a further speed improvement but it does prevent disk writes that are never read.

Section_8 · l33t Joined: 22 May 2004 Posts: 627

I recently upgraded from 8G to 16G. When I had a smallish /var/tmp/portage in tmpfs, I used the technique here: https://wiki.gentoo.org/wiki//etc/portage/package.env to configure packages needing a bigger /var/tmp/portage than my tmpfs (libreoffice) to automagically revert to a directory on disk.

pmam · Veteran Joined: 30 Dec 2013 Posts: 1145

krinn,

Nice to know about lshw - according output, RAM is working on 1066 MHZ and looks ok:

krinn · Watchman Joined: 02 May 2003 Posts: 7470

NeddySeagoon · Posted: Wed Aug 10, 2016 4:49 pm Post subject:

krinn,

That tells the core clock at the time the command is run.
With the assorted speed up/down technologies its easy to get different but equally correct CPU core speeds depending on the system load.

pmam,

You need a line in /etc/fstab to mount /var/tmp/portage, or whatever your build locations is, as tmpfs, or it won't be automatic.

Do not set size any more that about 6G without only 8G RAM.
tmpfs will swap to your swap partition when there is pressure on RAM. That's slower than normal HDD access as it uses the page size, which is normally 4k.

--edit --
4G is the default half of RAM.
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pmam · Veteran Joined: 30 Dec 2013 Posts: 1145

Here my frequency - A little bit

slower than krinn's machine, but looks fsb is well set. According MB spec above, FSB supported up to 1333 MHZ...