problems with new the "contigmalloc" routine

[John Baldwin]

On May 20, 2005, at 3:49 PM, Peter Jeremy wrote:
> On Fri, 2005-May-20 21:51:34 +0200, Hans Petter Selasky wrote:
>> Can anyone explain why "uiomove()" has to sleep, and why there is no
>> non-blocking "uiomove()"?
>
> As far as I can see, uiomove() only sleeps if it is asked to do a
> kernel<->userland move that takes more than twice a scheduler quantum.
> As long as you don't uiomove() ridiculous amounts of data, it should
> never sleep.

It can also sleep if it is reading from or writing to user memory if 
any of that memory needs to be faulted in.

-- 
John Baldwin <jhb at FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve"  =  http://www.FreeBSD.org