From: "Stephen C. Tweedie" <sct@redhat.com>
To: Jan Hudec <bulb@ucw.cz>, "Stephen C. Tweedie" <sct@redhat.com>,
"Joseph A. Knapka" <jknapka@earthlink.net>,
Martin Maletinsky <maletinsky@scs.ch>,
linux-mm@kvack.org, kernelnewbies@nl.linux.org
Subject: Re: kiobuf interface / PG_locked flag
Date: Fri, 13 Sep 2002 15:45:41 +0100 [thread overview]
Message-ID: <20020913154541.E17450@redhat.com> (raw)
In-Reply-To: <20020913124127.GB23303@artax.karlin.mff.cuni.cz>; from bulb@ucw.cz on Fri, Sep 13, 2002 at 02:41:27PM +0200
Hi,
On Fri, Sep 13, 2002 at 02:41:27PM +0200, Jan Hudec wrote:
> Ref-counts protect from swapping out. But it's the PG_locked flag, that
> protects from starting other IO. If you are writing, read must not
> happen. If you are reading, nothing else at all must happen. So that's
> the difference. map_use_kiobuf fault the pages in. lock_kiovec make
> sure, that noone (else) is doing ANU IO on the pages.
Depends on what semantics you want. There's nothing to stop a kiobuf
from being modified in flight. All the app has to do is create a
thread and modify the buffer from within that thread.
--Stephen
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next prev parent reply other threads:[~2002-09-13 14:45 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-09-12 8:48 kiobuf interface / PG_locked flag Martin Maletinsky
2002-09-12 15:24 ` Joseph A. Knapka
2002-09-12 15:33 ` Stephen C. Tweedie
2002-09-13 12:41 ` Jan Hudec
2002-09-13 14:45 ` Stephen C. Tweedie [this message]
2002-09-15 15:54 ` Jan Hudec
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