problems with new the "contigmalloc" routine
Don Lewis
truckman at FreeBSD.org
Fri May 20 22:56:32 GMT 2005
On 21 May, 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 stumbles across a userland page that isn't
resident. When this happens, it will sleep until the page is retrieved
from swap.
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