From: Karel Zak <kzak@redhat.com>
To: Rodrigo Campos <rodrigo@sdfg.com.ar>
Cc: util-linux@vger.kernel.org
Subject: Re: [PATCH v3] fallocate: Add "--dig-holes" option
Date: Fri, 14 Feb 2014 12:34:32 +0100 [thread overview]
Message-ID: <20140214113432.GB28125@x2.net.home> (raw)
In-Reply-To: <20140214104756.GA28125@x2.net.home>
On Fri, Feb 14, 2014 at 11:47:56AM +0100, Karel Zak wrote:
> I don't like all the detection algorithm. Do we really need to allocate
> all hole size and the buffer?
>
> IMHO it would be enough to:
>
> * add posix_fadvise(... POSIX_FADV_SEQUENTIAL | POSIX_FADV_NOREUSE)
>
> * read the file in small chunks -- for example BUFSIZ and compare
> this with small empty static buffer.
>
> .. it's kernel business to read from FS/device in optimal way and I
> don't think that context switches are so critical issue when all the
> thing is about I/O.
>
> I didn't test it, so maybe I'm wrong, but the current code where we
> eat RAM seems too crazy. Comments?
.. and another issue, the current code assumes that the holes are
aligned to hole_size that we read from the file. If the hole starts
within the buffer and continues in the next chunk than it's ignored.
Karel
--
Karel Zak <kzak@redhat.com>
http://karelzak.blogspot.com
next prev parent reply other threads:[~2014-02-14 11:34 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-25 19:17 fallocate: Add "--dig-holes" options and minor fixes Rodrigo Campos
2014-01-25 19:17 ` [PATCH 1/3] fallocate: Clarify that space can also be deallocated Rodrigo Campos
2014-01-25 19:17 ` [PATCH 2/3] fallocate: Hide #ifdef tricks to call fallocate in a function Rodrigo Campos
2014-01-25 19:17 ` [PATCH 3/3] fallocate: Add "--dig-holes" option Rodrigo Campos
2014-01-26 14:43 ` [PATCH v2] " Rodrigo Campos
2014-01-26 15:06 ` [PATCH v3] " Rodrigo Campos
2014-02-14 10:47 ` Karel Zak
2014-02-14 11:34 ` Karel Zak [this message]
2014-02-14 13:16 ` Rodrigo Campos
2014-02-14 13:07 ` Rodrigo Campos
2014-02-14 13:30 ` Karel Zak
2014-02-14 13:35 ` Rodrigo Campos
2014-02-17 10:32 ` Karel Zak
2014-02-17 14:15 ` Rodrigo Campos
2014-02-17 14:49 ` Karel Zak
2014-02-17 15:42 ` Rodrigo Campos
2014-01-25 19:23 ` fallocate: Add "--dig-holes" options and minor fixes Rodrigo Campos
[not found] ` <20140201040414.GA23360@sdfg.com.ar>
2014-02-11 11:31 ` Rodrigo Campos
2014-02-11 18:34 ` Karel Zak
2014-02-11 18:43 ` Rodrigo Campos
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