Re: [patch v2] epoll use a single inode ...

[Eric Dumazet]

Davide Libenzi a écrit :
> On Mon, 5 Mar 2007, H. Peter Anvin wrote:
>
> > Davide Libenzi wrote:
> > > Right now is using:
> > >
> > > 	this.len = sprintf(name, "[%u.%d]", current->pid, fd);
> > >
> > > That should be unique and not have the wraparound problem. Ack?
> > NAK, very much NAK.
> >
> > File descriptors aren't file structures, they're *pointers* to file
> > structures.
> >
> > It's perfectly possible -- downright common -- for a file descriptor to be
> > inherited by another process, and then the pid is recycled -- collision.
>
> Ugh! Right! 64 bit counter it is ... :)

For epoll, I suspect this is harmless : Programs dont allocate epolls fd every 
milli second, but at startup only.

For pipes/sockets, using a 64 bits would be problematic, because sprintf() 
uses a divide for each digit. And a divide is slow. Ten divides are *very* slow.


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