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Date:      Fri, 4 Dec 1998 13:48:36 +0100 (MET)
From:      Luigi Rizzo <luigi@labinfo.iet.unipi.it>
To:        toasty@home.dragondata.com (Kevin Day)
Cc:        hackers@FreeBSD.ORG
Subject:   Re: Nonblocking page fetching
Message-ID:  <199812041248.NAA08298@labinfo.iet.unipi.it>
In-Reply-To: <199812041431.IAA27124@home.dragondata.com> from "Kevin Day" at Dec 4, 98 08:31:20 am

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> I have an application where I'm streaming large amounts of data from disk,
...
> The hack I ended up using was another process that I could tell that I
> needed the frames, and all it did was sit in a for loop touching every page,
> to force them to be brought in.
> 
> This has some obvious disadvantages, but it stopped my movie player from
> sitting in vmwait when it could be doing other things.

is it so bad ? The forked process should consume very little memory
and because they are local you can even resort to or some cheap
local IPC mechanism to synchronize them. From a portability point of
view i think this is going to be to be better than provide a
specialised syscall.

> One final note... Does anyone know what effect turning off the bzero on new
> pages would be? Security is not an issue in this system, as it's not

again how bad is it ? bzero is generally done in the idle loop if i am
not mistaken so you should not be affected too badly by that unless you
are at or near 100% CPU usage.

	cheers
	luigi
-----------------------------+--------------------------------------
Luigi Rizzo                  |  Dip. di Ingegneria dell'Informazione
email: luigi@iet.unipi.it    |  Universita' di Pisa
tel: +39-50-568533           |  via Diotisalvi 2, 56126 PISA (Italy)
fax: +39-50-568522           |  http://www.iet.unipi.it/~luigi/
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