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Date:      Thu, 29 Jul 1999 09:48:57 -0700
From:      Jason Thorpe <thorpej@nas.nasa.gov>
To:        Matthew Dillon <dillon@apollo.backplane.com>
Cc:        "Daniel C. Sobral" <dcs@newsguy.com>, hackers@FreeBSD.ORG
Subject:   Re: MADV_SEQUENTIAL and GNU Grep 
Message-ID:  <199907291648.JAA29492@lestat.nas.nasa.gov>

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On Thu, 29 Jul 1999 09:26:12 -0700 (PDT) 
 Matthew Dillon <dillon@apollo.backplane.com> wrote:

 >     Yes, it will work.  Oops.  I do see one problem though... if you do
 >     this the underlying file object will be marked for sequential operation
 >     even after the grep (in this case) exits.  That is, an madvise() of
 >     MADV_NORMAL, SEQUENTIAL, or RANDOM appears to have a permanent effect 
 >     on the object.  This is probably not correct behavior.  We could probably
 >     fix this by moving this particular flag from the object to the vm_entry.

In NetBSD, we store advice in the map entry, specifically because two
different processes may wish to have different access patterns on the
same object.

Just a data point.

        -- Jason R. Thorpe <thorpej@nas.nasa.gov>



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