Re: [RFD w/info-PATCH] device arguments from lookup, partion code

Alexander Viro
2001-05-21T20:42:17Z

On Mon, 21 May 2001, Alan Cox wrote:

> > > I don't need to read it. Don't be insulting. Sure, you *can* use a
> > > write(2)/read(2) cycle. But that's two syscalls compared to one with
> > > ioctl(2) or transaction(2). That can matter to some applications.
> >
> > I just don't think so. Where did you see performance-critical use of
> > ioctl()?
>
> AGP, video4linux,...

Which, BTW, is a wonderful reason for having multiple channels. Instead
of write(fd, "critical_command", 8); read(fd,....); you read from the right fd.
Opened before you enter the hotspot. Less overhead than ioctl() would
have...