Date: Sat, 21 May 2005 13:43:03 +1000 From: Peter Jeremy <PeterJeremy@optushome.com.au> To: Don Lewis <truckman@freebsd.org> Cc: hselasky@c2i.net Subject: Re: problems with new the "contigmalloc" routine Message-ID: <20050521034303.GM2129@cirb503493.alcatel.com.au> In-Reply-To: <200505202256.j4KMuFN9055802@gw.catspoiler.org> References: <20050520224928.GI2129@cirb503493.alcatel.com.au> <200505202256.j4KMuFN9055802@gw.catspoiler.org>
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On Fri, 2005-May-20 15:56:15 -0700, Don Lewis wrote: >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. Mea culpa. I thought pcb_onfault was invoked in lieu of paging but it's actually invoked after the pager has tried to bring the page in. -- Peter Jeremy
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