Proc

Buddyinfo
From https://www.centos.org/docs/5/html/5.2/Deployment_Guide/s2-proc-buddyinfo.html

This file is used primarily for diagnosing memory fragmentation issues. Using the buddy algorithm, each column represents the number of pages of a certain order (a certain size) that are available at any given time. For example, for zone DMA (direct memory access), there are 90 of 2^(0*PAGE_SIZE) chunks of memory. Similarly, there are 6 of 2^(1*PAGE_SIZE) chunks, and 2 of 2^(2*PAGE_SIZE) chunks of memory available.

The DMA row references the first 16 MB on a system, the HighMem row references all memory greater than 4 GB on a system, and the Normal row references all memory in between.

The following is an example of the output typical of /proc/buddyinfo:

Node 0, zone DMA 90 6 2 1 1 …
Node 0, zone Normal 1650 310 5 0 0 …
Node 0, zone HighMem 2 0 0 1 1 …

Cmdline

This file shows the parameters passed to the kernel at the time it is started.

BOOT_IMAGE=/boot/vmlinuz-4.10.0-32-generic.efi.signed root=UUID=c513dc8d-5012-… ro quiet splash vt.handoff=7

Cpuinfo
From https://unix.stackexchange.com/questions/146051/number-of-processors-in-proc-cpuinfo

From Intel Spec.

# of Cores 2# of Threads 4Processor Base Frequency 2.50 GHzMax Turbo Frequency 3.10 GHzCache 4 MB SmartCacheBus Speed 4 GT/s OPITDP 15 WConfigurable TDP-up Frequency 2.60 GHzConfigurable TDP-up 25 WConfigurable TDP-down Frequency 800 MHzConfigurable TDP-down 7.5 W

28 processor : 1
29 vendor_id : GenuineIntel
30 cpu family : 6
31 model : 78
32 model name : Intel(R) Core(TM) i7-6500U CPU @ 2.50GHz
33 stepping : 3
34 microcode : 0xa2
35 cpu MHz : 2576.989
36 cache size : 4096 KB
37 physical id : 0
38 siblings : 4
39 core id : 1
40 cpu cores : 2
41 apicid : 2
42 initial apicid : 2
43 fpu : yes
44 fpu_exception : yes
45 cpuid level : 22
46 wp : yes
47 flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc art arch_perfmon pebs bts
48 bugs :
49 bogomips : 5184.00
50 clflush size : 64
51 cache_alignment : 64
52 address sizes : 39 bits physical, 48 bits virtual
53 power management:

“Siblings” means the number of threads and “cpu cores” means the actual core number in this processor.

Devices
From https://www.centos.org/docs/5/html/5.2/Deployment_Guide/s2-proc-devices.html

The output from /proc/devices includes the major number and name of the device, and is broken into two major sections: Character devices and Block devices.

Diskstats
From https://www.kernel.org/doc/Documentation/ABI/testing/procfs-diskstats

    The /proc/diskstats file displays the I/O statistics    of block devices. Each line contains the following 14    fields:     1 - major number     2 - minor mumber     3 - device name     4 - reads completed successfully     5 - reads merged     6 - sectors read     7 - time spent reading (ms)     8 - writes completed     9 - writes merged    10 - sectors written    11 - time spent writing (ms)    12 - I/Os currently in progress    13 - time spent doing I/Os (ms)    14 - weighted time spent doing I/Os (ms)    For more details refer to Documentation/iostats.txt

filesystems
From http://linuxinsight.com/proc_filesystems.html

A text listing of the filesystems which were compiled into the kernel. Incidentally, this is used by mount(1) to cycle through different filesystems when none is specified. The “nodev” string in the first column means that filesystem does not require a block device to be mounted, it’s so called virtual filesystem.

Interrupts
From https://www.centos.org/docs/5/html/5.1/Deployment_Guide/s2-proc-interrupts.html

The first column refers to the IRQ number. Each CPU in the system has its own column and its own number of interrupts per IRQ. The next column reports the type of interrupt, and the last column contains the name of the device that is located at that IRQ.

Each of the types of interrupts seen in this file, which are architecture-specific, mean something different. For x86 machines, the following values are common:

XT-PIC — This is the old AT computer interrupts.IO-APIC-edge — The voltage signal on this interrupt transitions from low to high, creating an edge, where the interrupt occurs and is only signaled once. This kind of interrupt, as well as the IO-APIC-level interrupt, are only seen on systems with processors from the 586 family and higher.IO-APIC-level — Generates interrupts when its voltage signal is high until the signal is low again.

iomem
From https://www.centos.org/docs/5/html/5.1/Deployment_Guide/s2-proc-iomem.html

The first column displays the memory registers used by each of the different types of memory. The second column lists the kind of memory located within those registers and displays which memory registers are used by the kernel within the system RAM or, if the network interface card has multiple Ethernet ports, the memory registers assigned for each port.

ioports
From https://www.centos.org/docs/5/html/5.1/Deployment_Guide/s2-proc-ioports.html

The first column gives the I/O port address range reserved for the device listed in the second column.