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

[Alan Cox]

> 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...

The ioctl is one syscall, the read/write pair are two. Im not sure that ioctl
is going to be more overhead there. In the video4linux case the high overhead
is acking frames received by mmap so might conceivably be considered one way