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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?

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swap == virtual memory –  Joakim Elofsson Sep 29 '09 at 13:49
    
Please give the specs of your CPU. Open the bios from startup of your system to determine your CPU's FSB. Or just google the model of your CPU. If you have a desktop PC, you could open the case and look at the cpu directly to find the model. –  Jonno_FTW Sep 30 '09 at 7:46
2  
No, swap and virtual memory are completely different. For example, memory mapping a 1GB file uses an additional 1GB of virtual memory but has no change in the use of swap. Swap is a form of backing store. Many uses of virtual memory don't have anything to do with backing store. (And there have been systems with virtual memory and no swap as well as systems with swap but no virtual memory.) –  David Schwartz Feb 18 '13 at 16:52

9 Answers 9

up vote 6 down vote accepted

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.

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Yes, swap is virtual memory.

Virtual memory size Use 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) speed You 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
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I have linux, it does not have dmidecode/lshw command –  pineapple Sep 30 '09 at 14:38
    
Which distro are you running? –  nagul Sep 30 '09 at 14:55
    
Also, do you have sudo access to run these commands on the machine? –  nagul Sep 30 '09 at 14:58

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)

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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
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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

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1 up, better than my solution :D, gives more info –  monkey_p Sep 29 '09 at 14:10

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.

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swapon -s

The used field will indicate the amount currently in use

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

$ getconf PAGESIZE

(or)

$ getconf PAGE_SIZE

Try

swapinfo or swapinfo -a
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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
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