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Hi, I'm little confused about amount of RAM memory in my computer and I can't figure out where disappear about 1GB memory. I need yours help to explain this, because i can't sleep :). Here is background: I've plugged into my computer 2x2GB RAM. In BIOS screen i see: Amount of available RAM: 4096MB so BIOS recognizes all 4GB, but my OS(32bit) uname -a Linux lpt 2.6.33.1 #1 SMP Thu Mar 18 23:32:41 CET 2010 i686 GNU/Linux sees only 3014MB free -m total used free shared buffers cached Mem: 3014 1756 1258 0 456 918 first, i thought that most of this missing memory is not available because of mapped IO, so i decided to count this by using addresses from /proc/iomem (where the actual memory map is). I've wrote piece of code like this to count all memory seen by OS: for i in `cat /proc/iomem | grep -P "^[^\s]" | awk '{ print $1}' | sort | uniq`; do startAddr=$(echo $i | awk -F "-" '{print $1}') && endAddr=$(echo $i | awk -F "-" '{print $2}'); bytes=$(calc "(0x$endAddr-0x$startAddr)"); ((sum+=${bytes})); done; echo "TotalMB: " ; calc "$sum/(1024*1024)"; TotalMB: 3745.726528167724609375 There is still missing almost 400MB. If i think correct, in /proc/iomem should be map of all memory, so it should cover all 4096 MB, right ?? Lets, count amount of ram not available for user, reserved for (mapped IO) ACPI, PCI bus etc: for i in `cat /proc/iomem | grep -v "System RAM" | grep -P "^[^\s]" | awk '{ print $1}' | sort | uniq`; do startAddr=$(echo $i | awk -F "-" '{print $1}') && endAddr=$(echo $i | awk -F "-" '{print $2}'); bytes=$(calc "(0x$endAddr-0x$startAddr)"); ((sum+=${bytes})); done; echo "TotalMB: " ; calc "$sum/(1024*1024)"; TotalMB: 683.65817165374755859375 Only 683MB, so if my calculation are correct, where disappear 400MB?? It seems to be that OS doesn't even sees this 400MB. Any idea? Extra logs: CPU is able to handle 36bit address size: cat /proc/cpuinfo | grep address address sizes : 36 bits physical, 48 bits virtual address sizes : 36 bits physical, 48 bits virtual Enabled PAE in kernel - but in this case there should not be difference (RAM isn't above 4GB) cat /boot/config-2.6.33.1 | grep PAE CONFIG_X86_PAE=y My iomem: root@lpt:~# cat /proc/iomem 00000000-00001fff : System RAM 00002000-0000ffff : reserved 00010000-0009f7ff : System RAM 0009f800-0009ffff : reserved 000a0000-000bffff : Video RAM area 000c0000-000c7fff : Video ROM 000cf000-000d07ff : Adapter ROM 000e0000-000fffff : reserved 000f0000-000fffff : System ROM 00100000-bf67ffff : System RAM 00100000-005951c8 : Kernel code 005951c9-007be6e7 : Kernel data 00854000-008dfadb : Kernel bss bf680000-bf6fffff : ACPI Non-volatile Storage bf700000-bfffffff : reserved c0000000-c3ffffff : PCI Bus 0000:06 c0000000-c3ffffff : PCI CardBus 0000:07 c4000000-c41fffff : PCI Bus 0000:02 c4200000-c43fffff : PCI Bus 0000:02 c4400000-c45fffff : PCI Bus 0000:03 c4600000-c47fffff : PCI Bus 0000:03 c4800000-c49fffff : PCI Bus 0000:04 c4a00000-c4bfffff : PCI Bus 0000:04 c4c00000-c4dfffff : PCI Bus 0000:05 c4e00000-c4e00fff : Intel Flush Page c8000000-cbffffff : PCI CardBus 0000:07 d0000000-dfffffff : 0000:00:02.0 e0000000-efffffff : PCI MMCONFIG 0000 [bus 00-ff] e0000000-efffffff : reserved e0000000-efffffff : pnp 00:01 f0000000-f007ffff : 0000:00:02.0 f0080000-f00fffff : 0000:00:02.1 f0100000-f01fffff : PCI Bus 0000:05 f0100000-f0100fff : 0000:05:00.0 f0100000-f0100fff : iwl3945 f0200000-f02fffff : PCI Bus 0000:06 f0200000-f0201fff : 0000:06:01.0 f0200000-f0201fff : 0000:06:01.0 f0202000-f0202fff : 0000:06:04.0 f0202000-f0202fff : yenta_socket f0203000-f020307f : 0000:06:04.1 f0203100-f02031ff : 0000:06:04.4 f0203100-f02031ff : mmc1 f0203400-f02034ff : 0000:06:04.2 f0203400-f02034ff : mmc0 f0203800-f020387f : 0000:06:04.3 f0300000-f033ffff : 0000:00:02.0 f0340000-f0343fff : 0000:00:1b.0 f0340000-f0343fff : ICH HD audio f0544000-f05443ff : 0000:00:1d.7 f0544000-f05443ff : ehci_hcd fec00000-fec0ffff : reserved fec00000-fec003ff : IOAPIC 0 fed00000-fed003ff : HPET 0 fed00000-fed003ff : reserved fed00000-fed003ff : pnp 00:04 fed14000-fed19fff : reserved fed14000-fed17fff : pnp 00:01 fed18000-fed18fff : pnp 00:01 fed19000-fed19fff : pnp 00:01 fed1c000-fed8ffff : reserved fed1c000-fed1ffff : pnp 00:01 fed20000-fed3ffff : pnp 00:01 fee00000-fee00fff : Local APIC fee00000-fee00fff : reserved ff000000-ffffffff : reserved -- regards Andrzej Kardas http://www.linux.mynotes.pl |
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