what actully number of forks since system start indicate.

[kuldeep saroha]

i what to know what is the meaning of number forks in vmstat output since system start. and what is semaphore.

[Don Morris_1 · Accepted solution]

"man 2 fork" -- but in short, fork() is the system call made when a process makes a copy of itself. That copy (a child process) may continue to do work using the data set as defined at the time of fork, may then call exec() to use its execution context as the basis for a new process image, etc. [This is how shells work -- though they should use vfork+exec for speed].

A semaphore is a synchronization primitive.
http://en.wikipedia.org/wiki/Semaphore_(programming)

[kuldeep saroha]

17529382 forks, 1237579058386 pages, average= 70600.27

4am up 96 days, 19:53, 5 users, load average: 0.57, 0.58, 0.48

is number of frok will impact the server performance. i ahve the aboue stats. during production time load reachs to 5.0. is there some relation of number forks with it.

[Dennis Handly]

>is number of fork will impact the server performance.

The fork rate will but not the total number.

>I have the above stats. during production time load reaches to 5.0. is there some relation of number forks with it.

A load of 5 doesn't mean much unless your system is slow. A "load" is just a process in the run queue.

You don't have to have a large number of forks to have a slow system. If it is a problem, top will show processes using lots of CPU time but quickly die.