[clug] Semaphores and shared memory

[Jepri]

Martin Pool wrote:

>On  9 Dec 2003, Jepri <jepri at webone.com.au> wrote:
>  
>
>>I've got some chunky data files that I would like to access at the same 
>>time from different programs.  I know that I can mmap the files into 
>>    
>>
>
>Just lock the file.  man lockf.
>  
>

Would that work when I'm reading and writing to the file at the same 
time (through mmaped memory)?  And what's the performance hit like?