How to find virtual memory size and cache size of a linux system?

Is there any command to get virtual memory size, cache size and front side bus speed of a linux system? Is swap in linux same as virtual memory?

9 Answers

This question is completely contained in your previous question How to find virtual memory size and cache size of a linux system?. As pointed out in my answer to that question, the sudo dmidecode --type processor command gives you the "External Clock" speed, and FSB speed is a multiple (typically 2 or 4 times) of this speed.

If this did not work for you, you should edit your original question and tell us what output you got or what the error was. The more specific you are, the better others can help you.

As pointed out by The Journeyman geek, you can typically get the same "External Clock" measure from lshw, in the value reported for "clock" in the cpu related ouput.

 *-cpu description: CPU product: Genuine Intel(R) CPU T2300 @ 1.66GHz vendor: Intel Corp. physical id: 400 bus info: cpu@0 version: 6.14.8 serial: 0000-06E8-0000-0000-0000-0000 slot: Microprocessor size: 1GHz capacity: 1800MHz width: 32 bits clock: 133MHz capabilities: fpu fpu_exception wp vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx constant_tsc arch_perfmon bts pni monitor est tm2 xtpr pdcm cpufreq configuration: id=0

Finally, you may find the external clock speed in the output of dmesg, though this is by no means a standard way of accessing this information. You may find the FSB speed via your BIOS settings, or by looking up your CPU spec, though these are not linux specific.

Yes, swap is virtual memory.

Virtual memory sizeUse swapon -s or free

$ swapon -s
Filename Type Size Used Priority
/dev/sda6 partition 1004020 39620 -1
$ free total used free shared buffers cached
Mem: 3087892 2879036 208856 0 394288 835052
-/+ buffers/cache: 1649696 1438196
Swap: 1004020 39620 964400

Cache size Get this from /proc/cpuinfo. The "cache size" field gives you the cache on the CPU. On multi-core machines, you'll see one entry per processor, with its own cache value.

$ cat /proc/cpuinfo
processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 14
model name : Genuine Intel(R) CPU T2300 @ 1.66GHz
stepping : 8
cpu MHz : 1000.000
cache size : 2048 KB
physical id : 0
siblings : 2
core id : 0
cpu cores : 2
apicid : 0
initial apicid : 0
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 10
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx constant_tsc arch_perfmon bts pni monitor est tm2 xtpr pdcm
bogomips : 3324.64
clflush size : 64
power management:

Front side bus (FSB) speedYou can get this from the dmidecode utility, with the --type processor argument. You need sudo permission to run this command. The FSB is indicated by the speed reported for "External Clock". The actual speed is typically 4 times the reported speed, as those many instructions are executed per clock cycle.

$ sudo dmidecode --type processor
# dmidecode 2.9
SMBIOS 2.4 present.
Handle 0x0400, DMI type 4, 32 bytes
Processor Information
Socket Designation: Microprocessor
Type: Central Processor
Family: Pentium M
Manufacturer: Intel
ID: E8 06 00 00 FF FB E9 BF
Signature: Type 0, Family 6, Model 14, Stepping 8
Flags: FPU (Floating-point unit on-chip) VME (Virtual mode extension) DE (Debugging extension) PSE (Page size extension) TSC (Time stamp counter) MSR (Model specific registers) PAE (Physical address extension) MCE (Machine check exception) CX8 (CMPXCHG8 instruction supported) APIC (On-chip APIC hardware supported) SEP (Fast system call) MTRR (Memory type range registers) PGE (Page global enable) MCA (Machine check architecture) CMOV (Conditional move instruction supported) PAT (Page attribute table) CLFSH (CLFLUSH instruction supported) DS (Debug store) ACPI (ACPI supported) MMX (MMX technology supported) FXSR (Fast floating-point save and restore) SSE (Streaming SIMD extensions) SSE2 (Streaming SIMD extensions 2) SS (Self-snoop) HTT (Hyper-threading technology) TM (Thermal monitor supported) PBE (Pending break enabled)
Version: Not Specified
Voltage: 3.3 V
External Clock: 133 MHz
Max Speed: 1800 MHz
Current Speed: 1000 MHz
Status: Populated, Enabled
Upgrade: None
L1 Cache Handle: 0x0700
L2 Cache Handle: 0x0701
L3 Cache Handle: Not Provided

I do believe lshw has that info. However not all distros have it (hint- next time PLEASE mention what distro and version you use. It helps a lot. Also helps to be specific about what you did so far. 'some command like' is not good enough)

Try this on the Linux machine: cat /proc/pal/cpu0/cache_info

This will show something like:

Cache levels : 3
Unique caches : 5
Data Cache level 1: Size : 16384 bytes Attributes : WriteThrough Associativity : 4 Line size : 64 bytes Stride : 128 bytes Store latency : 0 cycle(s) Load latency : 1 cycle(s) Store hints : Load hints : [Temporal, level 1] Alias boundary : 4096 byte(s) Tag LSB : 12 Tag MSB : 49
Instruction Cache level 1: Size : 16384 bytes Attributes : Associativity : 4 Line size : 64 bytes Stride : 128 bytes Store latency : N/A Load latency : 1 cycle(s) Store hints : Load hints : [Temporal, level 1] Alias boundary : 4096 byte(s) Tag LSB : 12 Tag MSB : 49
Data Cache level 2: Size : 262144 bytes Attributes : WriteBack Associativity : 8 Line size : 128 bytes Stride : 128 bytes Store latency : 7 cycle(s) Load latency : 5 cycle(s) Store hints : [Temporal, level 1][Non-temporal, all levels] Load hints : [Temporal, level 1][Non-temporal, level 1][Non-temporal, all levels] Alias boundary : 4096 byte(s) Tag LSB : 15 Tag MSB : 49
Instruction Cache level 2: Size : 524288 bytes Attributes : Associativity : 8 Line size : 128 bytes Stride : 128 bytes Store latency : N/A Load latency : 7 cycle(s) Store hints : Load hints : [Temporal, level 1][Non-temporal, level 1][Non-temporal, all levels] Alias boundary : 4096 byte(s) Tag LSB : 16 Tag MSB : 49
Data/Instruction Cache level 3: Size : 4194304 bytes Attributes : Unified WriteBack Associativity : 8 Line size : 128 bytes Stride : 128 bytes Store latency : 7 cycle(s) Load latency : 14 cycle(s) Store hints : [Temporal, level 1] Load hints : [Temporal, level 1][Non-temporal, level 1] Alias boundary : 4096 byte(s) Tag LSB : 19 Tag MSB : 49

Try ulimit -a, on my machine it will show something like:

core file size (blocks, -c) 0
data seg size (kbytes, -d) unlimited
scheduling priority (-e) 0
file size (blocks, -f) unlimited
pending signals (-i) 31321
max locked memory (kbytes, -l) 64
max memory size (kbytes, -m) unlimited
open files (-n) 1024
pipe size (512 bytes, -p) 8
POSIX message queues (bytes, -q) 819200
real-time priority (-r) 0
stack size (kbytes, -s) 8192
cpu time (seconds, -t) unlimited
max user processes (-u) 31321
virtual memory (kbytes, -v) unlimited
file locks (-x) unlimited

Run free, on my machine the result is like this:

 total used free shared buffers cached
Mem: 4024900 606472 3418428 0 85768 366980
-/+ buffers/cache: 153724 3871176
Swap: 3998716 0 3998716

I wrote this code to test how many threads a process can create:

#include<iostream>
#include<pthread.h>
#include<unistd.h>
#include<stdio.h>
using namespace std;
#define MAX_THREAD_NUM 1100
void * threadTest(void* arg){ while(true){ sleep(5); } pthread_exit(NULL);
}
int main(){ for(int i = 0;i< MAX_THREAD_NUM;i++){ pthread_t tid; cout<<"create thread "<< i <<"... "<<endl; int ret = pthread_create(&tid,NULL,&threadTest,NULL); if(ret !=0){ perror("pthread_create error"); } pthread_detach(tid); } while(true){ sleep(5); } return 0;
}

The result is like this:

create thread 378...
create thread 379...
create thread 380...
create thread 381...
create thread 382...
pthread_create error: Cannot allocate memory
create thread 383...
pthread_create error: Cannot allocate memory
create thread 384...
pthread_create error: Cannot allocate memory
create thread 385...
pthread_create error: Cannot allocate memory
create thread 386...
pthread_create error: Cannot allocate memory

vmstat

vmstat reports report virtual memory statistics, which has information about processes, swap, free, buffer and cache memory, paging space, disk IO activity, traps, interrupts, context switches and CPU activity. With vmstat command, administrators can has instantaneous reports on memory usage.

Syntax of vmstat

vmstat -[options] [delay count]

Example usage of vmstat

vmstat

Found here

The "free" command will show you memory utilization, including what's actually being used vs what's in buffers / cache.

 # free total used free shared buffers cached
Mem: 3896252 3779044 117208 0 65788 1363972
-/+ buffers/cache: 2349284 1546968
Swap: 2097144 886836 1210308

The "dmidecode" command might give you some insight into the FSB speed.

swapon -s

The used field will indicate the amount currently in use

Filename Type Size Used Priority
/dev/sda5 partition 859436 0 -1

Page Size :

$ getconf PAGESIZE

(or)

$ getconf PAGE_SIZE

Try

swapinfo or swapinfo -a

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How to find virtual memory size and cache size of a linux system?

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