Login or Register to Ask a Question and Join Our Community

Sponsored Content
Full Discussion: semaphore access speed
Top Forums Programming semaphore access speed Post 302237980 by migurus on Thursday 18th of September 2008 09:22:22 PM
Old 09-18-2008
I simplified my program to the very basic minimum, it gets ipc key, gets semaphore id and reads values of semaphores and then it outputs on line (time and semaphore values). That is all it does.

Then I run it in following manner:
$ while : ; do tstshow; done > x.txt
and I hit interrupt key after waiting for some time.

sample of the x.txt file content:
1221785538 [1,99]
1221785538 [1,99]
1221785538 [1,99]


Then to see how many times system was able to run it I do:
$ cut -c-12 x.txt | uniq -c

sample of the output:
616 1221785538
615 1221785539
612 1221785540

That tels me the system is capable of running this simple process just roughly 600 times per second.

Just to be consistent I would repeat results here:
PIII under Linux - 900 times/sec
Xeon 3.2 Linux - 600 times/sec
Xeon 3.2 SCO - 1800 times/sec
Systems are idle at the time of test.
How would you explain the results I got? I am trying to find a bottleneck on the modern h/w running Linux.

Please see my new simplified code below:

Code:
 
#include <stdio.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/sem.h>
#include <time.h>
#define NSEMS   2
main(int argc, char *argv[])
{
  int           sid;
  ushort        vals[NSEMS] = {0, 0};
        if((sid = semget(get_ipc_key(), NSEMS, 0)) == -1)
        {
                errexit("Can Not Get Semaphore ID");
        }
        if(semctl(sid, NSEMS, GETALL, vals) == -1)
        {
                errexit("Can Not Get Semaphore Values");
        }
        printf("%12li [%i,%i]\n", time(NULL), vals[0], vals[1]);
        exit(0);
}

 

9 More Discussions You Might Find Interesting

1. UNIX for Dummies Questions & Answers

semaphore

hi, is there any command where we can monitor semaphores? (1 Reply)
Discussion started by: yls177
1 Replies

2. UNIX for Dummies Questions & Answers

Semaphore

Hi, I'm new to UNIX. I need to know what's a semaphore Do reply. Thanks VJ (3 Replies)
Discussion started by: vjsony
3 Replies

3. Filesystems, Disks and Memory

dmidecode, RAM speed = "Current Speed: Unknown"

Hello, I have a Supermicro server with a P4SCI mother board running Debian Sarge 3.1. This is the "dmidecode" output related to RAM info: RAM speed information is incomplete.. "Current Speed: Unknown", is there anyway/soft to get the speed of installed RAM modules? thanks!! Regards :)... (0 Replies)
Discussion started by: Santi
0 Replies

4. Shell Programming and Scripting

Semaphore

Hi, I am looking to use a semaphore for the first time in one of my scripts. I am just wondering if there are any simple examples or tutorials around? I am a beginner so the simpler the better :) Thanks -Jaken (2 Replies)
Discussion started by: Jaken
2 Replies

5. UNIX for Dummies Questions & Answers

semaphore

what is semaphore? can any body explain it in a more simple way than the manual ?? replies appreciated Regards raguram R (7 Replies)
Discussion started by: raguramtgr
7 Replies

6. Filesystems, Disks and Memory

data from blktrace: read speed V.S. write speed

I analysed disk performance with blktrace and get some data: read: 8,3 4 2141 2.882115217 3342 Q R 195732187 + 32 8,3 4 2142 2.882116411 3342 G R 195732187 + 32 8,3 4 2144 2.882117647 3342 I R 195732187 + 32 8,3 4 2145 ... (1 Reply)
Discussion started by: W.C.C
1 Replies

7. Shell Programming and Scripting

semaphore

Control two exclusively shared resources(semaphore). The two resources are two files. The producer will write even numbers to one file, and odd numbers to another one. The consumer respectively reads from each file until it gets 5 even numbers and 5 odd numbers. Can any one help me with the... (0 Replies)
Discussion started by: gokult
0 Replies

8. Programming

Semaphore

If I create a semaphore and then I fork a number of child processes then all the child process use that same semaphore. Since the process address spaces are different rfom each other then how all the child process are able to access the same semaphore? I understand that semaphore/mutex is at os... (0 Replies)
Discussion started by: rupeshkp728
0 Replies

9. UNIX for Beginners Questions & Answers

Semaphore

I was asked to add this piece of code to a c program which I will execute through the shell: for(long i = 0; i < NITER; i++) { sem_wait( &sema); count++; sem_post( &sema); } I didn't get it, which is the critical section ? if it's "count++" how would a thread wake up in order to enter it... (1 Reply)
Discussion started by: uniran
1 Replies

LEARN ABOUT DEBIAN

set_color

set_color(1)							       fish							      set_color(1)

NAME

       set_color - set_color - set the terminal color

set_color - set the terminal color
   Synopsis
       set_color [-v --version] [-h --help] [-b --background COLOR] [COLOR]

   Description
       Change the foreground and/or background color of the terminal. COLOR is one of black, red, green, brown, yellow, blue, magenta, purple,
       cyan, white and normal.

       o -b, --background Set the background color

       o -c, --print-colors Prints a list of all valid color names

       o -h, --help Display help message and exit

       o -o, --bold Set bold or extra bright mode

       o -u, --underline Set underlined mode

       o -v, --version Display version and exit

       Calling set_color normal will set the terminal color to whatever is the default color of the terminal.

       Some terminals use the --bold escape sequence to switch to a brighter color set. On such terminals, set_color white will result in a grey
       font color, while set_color --bold white will result in a white font color.

       Not all terminal emulators support all these features. This is not a bug in set_color but a missing feature in the terminal emulator.

       set_color uses the terminfo database to look up how to change terminal colors on whatever terminal is in use. Some systems have old and
       incomplete terminfo databases, and may lack color information for terminals that support it. Download and install the latest version of
       ncurses and recompile fish against it in order to fix this issue.

Version 1.23.1							  Sun Jan 8 2012						      set_color(1)
All times are GMT -4. The time now is 02:22 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy