linuxcnc 2.8.4 RTAI does not sees 4GB of RAM, only 2.8GB
12 Oct 2022 13:37 #254020
by tarasko
linuxcnc 2.8.4 RTAI does not sees 4GB of RAM, only 2.8GB was created by tarasko
Hello. I'm using linuxcnc 2.8.4 RTAI i386 version.
My problem is when I'm trying to load huge file (800MB) OOM kills linuxcnc because RAM is ran out. I turned on SWAP (9gb)
and this didn't help.
I have 4GB RAM installed but linux kernel sees only 2.8GB
Please help me to enable the rest of 4GB of RAM for this kernel.
My problem is when I'm trying to load huge file (800MB) OOM kills linuxcnc because RAM is ran out. I turned on SWAP (9gb)
and this didn't help.
I have 4GB RAM installed but linux kernel sees only 2.8GB
optimus@optimus:~$ sudo grep -i memory /var/log/dmesg
[ 0.000000] initial memory mapped : 0 - 01800000
[ 0.000000] Base memory trampoline at [c0098000] 98000 size 16384
[ 0.000000] init_memory_mapping: 0000000000000000-00000000377fe000
[ 0.000000] Early memory PFN ranges
[ 0.000000] PM: Registered nosave memory: 000000000009c000 - 000000000009d000
[ 0.000000] PM: Registered nosave memory: 000000000009d000 - 00000000000a0000
[ 0.000000] PM: Registered nosave memory: 00000000000a0000 - 00000000000e0000
[ 0.000000] PM: Registered nosave memory: 00000000000e0000 - 0000000000100000
[ 0.000000] PM: Registered nosave memory: 0000000020000000 - 0000000020100000
[ 0.000000] please try 'cgroup_disable=memory' option if you don't want memory cgroups
[ 0.000000] Memory: 2921108k/2981888k available (3495k kernel code, 50372k reserved, 1237k data, 416k init, 2063664k highmem)
[ 0.000000] virtual kernel memory layout:
[ 0.000428] Initializing cgroup subsys memory
[ 0.865040] Freeing initrd memory: 14268k freed
[ 1.250880] Freeing unused kernel memory: 416k freed
optimus@optimus:~$Please help me to enable the rest of 4GB of RAM for this kernel.
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12 Oct 2022 23:44 #254047
by arvidb
Replied by arvidb on topic linuxcnc 2.8.4 RTAI does not sees 4GB of RAM, only 2.8GB
Basically, you will not be able to utilize more than 3 GiB of RAM with a 32-bit kernel. This is because of how the kernel splits the available 4 GiB (32 bit) address space between internal use (1 GiB) and user space (3 GiB).
You could look into PAE (Physical Address Extension) but I'm not sure if that is compatible with a realtime kernel. Huh, well it seems it is: packages.debian.org/buster/kernel/linux-image-rt-686-pae
A better solution though: switch to a 64 bit system.
Or use smaller files.
You could look into PAE (Physical Address Extension) but I'm not sure if that is compatible with a realtime kernel. Huh, well it seems it is: packages.debian.org/buster/kernel/linux-image-rt-686-pae
A better solution though: switch to a 64 bit system.
Or use smaller files.
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13 Oct 2022 00:30 #254048
by tommylight
Replied by tommylight on topic linuxcnc 2.8.4 RTAI does not sees 4GB of RAM, only 2.8GB
Pretty sure the official Wheezy ISO uses a 32 bit PAE kernel version 3.4.9 and is still available for download.
linuxcnc.org/iso/linuxcnc-2.7.14-wheezy.iso
linuxcnc.org/iso/linuxcnc-2.7.14-wheezy.iso
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13 Oct 2022 02:11 #254051
by arvidb
Replied by arvidb on topic linuxcnc 2.8.4 RTAI does not sees 4GB of RAM, only 2.8GB
tarasko: What does 'uname -a' report?
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