From: Steve Lord <lord@xfs.org>
To: Werner Almesberger <wa@almesberger.net>
Cc: linux-fsdevel@vger.kernel.org
Subject: Re: barriers vs. reads
Date: Thu, 24 Jun 2004 11:39:11 -0500 [thread overview]
Message-ID: <40DB03AF.7090706@xfs.org> (raw)
In-Reply-To: <20040623214845.A21586@almesberger.net>
Werner Almesberger wrote:
> BTW, regarding overlapping requests, I wonder if there's a data
> structure that gives O(log requests) or such lookups for ranges.
> The best I could spontaneously think of would be
> O(new_request_size*log(requests*avg_request_size))
> which isn't pretty.
>
> BTW2, is O_DIRECT actually a Linux-only thing, or is there some
> ancestor whose semantics we may want to preserve ? I've had a
> quick look at POSIX, but they don't seem to have direct IO.
Irix has O_DIRECT, Solaris has something too, but it is not
in the posix specs. Cray Unicos is the oldest implementation I came
across.
Irix explicitly lets multiple readers and writers into a file
at once with O_DIRECT. The assumption being that the application
which does this is doing its own coordination and will not
shoot itself in the foot.
Steve Lord
next prev parent reply other threads:[~2004-06-24 16:40 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-06-24 0:48 barriers vs. reads Werner Almesberger
2004-06-24 3:39 ` Werner Almesberger
2004-06-24 8:00 ` Herbert Poetzl
2004-06-24 12:16 ` Werner Almesberger
2004-06-24 13:36 ` Jamie Lokier
2004-06-24 17:02 ` Werner Almesberger
2004-06-24 16:39 ` Steve Lord [this message]
2004-06-24 17:00 ` barriers vs. reads - O_DIRECT Bryan Henderson
2004-06-24 17:46 ` Werner Almesberger
2004-06-24 18:50 ` Jamie Lokier
2004-06-24 20:55 ` Werner Almesberger
2004-06-24 22:42 ` Jamie Lokier
2004-06-25 3:21 ` Werner Almesberger
2004-06-25 3:57 ` Guy
2004-06-25 4:52 ` Werner Almesberger
2004-06-25 0:11 ` Bryan Henderson
2004-06-25 2:42 ` Werner Almesberger
2004-06-25 15:59 ` barriers vs. reads - O_DIRECT aio Bryan Henderson
2004-06-25 16:31 ` barriers vs. reads - O_DIRECT Bryan Henderson
-- strict thread matches above, loose matches on Subject: below --
2004-06-22 3:53 barriers vs. reads Werner Almesberger
2004-06-22 7:39 ` Jens Axboe
2004-06-22 7:50 ` Werner Almesberger
2004-06-22 7:55 ` Jens Axboe
2004-06-22 8:34 ` Werner Almesberger
2004-06-22 10:08 ` Jens Axboe
2004-06-22 11:28 ` Jamie Lokier
2004-06-22 11:32 ` Jens Axboe
2004-06-22 17:12 ` Bryan Henderson
2004-06-22 20:53 ` Jens Axboe
2004-06-23 16:41 ` Bryan Henderson
2004-06-23 16:52 ` Jens Axboe
2004-06-23 16:53 ` Jamie Lokier
2004-06-23 21:08 ` Bryan Henderson
2004-06-23 23:23 ` Werner Almesberger
2004-06-24 13:43 ` Jamie Lokier
2004-06-24 14:32 ` Christoph Hellwig
2004-06-24 17:05 ` Werner Almesberger
2004-06-22 18:53 ` Werner Almesberger
2004-06-22 19:57 ` Jamie Lokier
2004-06-22 23:13 ` Werner Almesberger
2004-06-22 20:57 ` Jens Axboe
2004-06-22 23:10 ` Werner Almesberger
2004-06-23 0:14 ` Jamie Lokier
2004-06-23 6:27 ` Jens Axboe
2004-06-22 18:45 ` Werner Almesberger
2004-06-22 19:07 ` Guy
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