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- 05-16-2013 #1
Lots of unused memory!
Hi all, I have a machine that I use to build images for use on a plug computer. Since it takes a little while to build these images I started watching the system monitor to see how the resources were being used. I was quite surprised to see that only about 1.7% of my memory was being used. So I watched more closely and sure enough it ranged from 1.1 to 1.7%.
I have 32 GB of memory on this thing and I wish to use it, so does anyone know what to change or tweak to make this happen? I've changed 'swappiness' to 10 but no change in memory usage. Since I'm doing compiles, linkage and scripts I would think it would run much faster using more memory.
Should I post this elsewhere?
- 05-16-2013 #2
How large are your image files and what distro and software is being used to process them?
Also, knowing specifics about hardware and if images are multi-band, 32-bit color, etc would be useful.
Personally, I woud be grateful to use only approcimately 550MB of my RAM to obtain the image desired!
Why the concern?"What you think about me is none of my business"
Mint-15-xfce | Slacko Pup 5.5
- 05-16-2013 #3
- 05-16-2013 #4
I'm using Debian Linux, 3.2.0-4-686-pae, and it states that all the build tools are up to date, but I don't know specifics. The resultant image is right around 2GB as we are building a Debian Linux Image to run on the plug-computer so it's Wheezy that we are building. It does swap a lot, but I'm not sure where to get specifics on any of these items. I've watched the 'system monitor' to get some idea of what's going on and I consistently have 31+ GB of memory free. Seems it should be using more than that and swapping less?
The run usually takes a half hour or so, but I have lots of ram, and it's not being used. I was just wondering if there are ways to allow more ram or restrict it so I can check these and see if they are reducing the ram usage and letting it swap. The swappiness didn't seem to make any difference. Maybe I should set it to 1 or 0 and see what happens?
I've been in computers many years and when they tune them they always seem to set them up to have little left during the run, which seems right to me as using the most memory and less swapping. Since ram is so much faster and I have it installed, I wish to use it and I'm finding that the system tools are not showing much use if any.
That's my concerns,. If you want anything specific, you need to address how to obtain what you desire. I'm relatively new on Linux and finding some specifics on this is an area I have little experience with.
This is an adendum, I set the monitor tools to show swap and it looks like it's not really swapping anything in or out. I can't believe that can do all of this in 1/2 MB! Maybe they can. I still think there must be an option to use more memory or a limit size that can be changed. I guess that's why there is no difference when I set swappiness to 10!
Last edited by jkwilborn; 05-16-2013 at 04:11 PM.
- 05-16-2013 #5
A couple of possibilities:
1. Turn your swap off by runningCode:
2. Build your images in /tmp which you can mount in RAM.
As root, edit /etc/fstab and add tmpfs /tmp tmpfs size=4096m 0 0 to the end of it on a blank line. You can change the 4096 to any size you want. This allocates 4GB. Once you have saved the file runCode:
Building your images to /tmp will effectively be building them to RAM; with the added bonus of everything else written to /tmp also being blindingly fast! On the down side, you will have to copy or move the image elsewhere once it is built. It might still be quicker than writing the image directly to hard disk.
Back up your fstab before making any changes as you can completely break your system by getting it wrong. With a backup, it is nothing a live CD can't fix!
- 05-16-2013 #6
Nice, I like that. I will give that a try and see if I can see an decrease in time required. It was right in front of me and I didn't even think about a ramdisk.
- 05-26-2013 #7
Created the swap file as you suggested. It is much quicker, went from about 40 minutes to little less than 30 for a build. But as usual I seem to have gobs of memory left over that is never used.
I just scanned an 8 X 10 color photo that produces a 1.4 GB tiff file. When I try to open the file I get an error from some packages that it fails because of lack of memory. I'm not exactly sure of what it's saying, but it does not let me view the image. I do have a listing of the /proc/meminfo if that is of any help to anyone. I don't seem to see anything that tells me what's happening except that it seems to know I have 32 GB. Does anybody see anything that would tip them off as to why usage of main memory is shown as low? The highest is usually only a couple of percent.
I have heard of people rebuilding the kernel with options showing a different memory limit, but mine is being shown by the OS as all there so something must be limiting it use somewhere. This is the only OS I've ever had this problem with! It would be nice to be able to use some of the applications to edit these large tiff or jpeg files (or even view them!)
# cat /proc/meminfo MemTotal: 33153104 kB MemFree: 27243036 kB Buffers: 159596 kB Cached: 4986188 kB SwapCached: 0 kB Active: 4757288 kB Inactive: 997656 kB Active(anon): 702120 kB Inactive(anon): 208536 kB Active(file): 4055168 kB Inactive(file): 789120 kB Unevictable: 16 kB Mlocked: 16 kB HighTotal: 32516352 kB HighFree: 26894936 kB LowTotal: 636752 kB LowFree: 348100 kB SwapTotal: 46387192 kB SwapFree: 46387192 kB Dirty: 72 kB Writeback: 0 kB AnonPages: 609176 kB Mapped: 127868 kB Shmem: 301496 kB Slab: 108240 kB SReclaimable: 79204 kB SUnreclaim: 29036 kB KernelStack: 3064 kB PageTables: 7860 kB NFS_Unstable: 0 kB Bounce: 0 kB WritebackTmp: 0 kB CommitLimit: 62963744 kB Committed_AS: 2711244 kB VmallocTotal: 122880 kB VmallocUsed: 32996 kB VmallocChunk: 65380 kB HardwareCorrupted: 0 kB AnonHugePages: 0 kB HugePages_Total: 0 HugePages_Free: 0 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 2048 kB DirectMap4k: 10232 kB DirectMap2M: 901120 kB
- 05-26-2013 #8
- 05-26-2013 #9
eliija, thanks for reading and asking, it is a 64 bit OS and I'm just double clicking on the file in a file browser. I've tried invoking it via the command line and get the same, I believe.
I would have thought that if I were to look at memory with a 32 bit system it would not show the complete 32 GB in the /proc/meminfo file, but don't know. My system is Wheezy with "3.2.0-4-686-pae" as probably a better identifier...
Thanks for any suggestions you may have. I've looked at a number of boards, but it appears that questions like it have been asked with little or no replies.
- 05-26-2013 #10
OK, 3.2.0-4-686-pae is a 32 bit pae kernel. Pae allows a 32 bit kernel to address upto 64GB of RAM but an individual process is still limited to 4GB which could explain the lack of memory use. A 64 bit kernel is usually identified as x86_64.