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From: Jeremy Fitzhardinge <jeremy@goop.org>
To: Dan Magenheimer <dan.magenheimer@oracle.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	chris.mason@oracle.com, viro@zeniv.linux.org.uk, adilger@Sun.COM,
	tytso@mit.edu, mfasheh@suse.com, joel.becker@oracle.com,
	matthew@wil.cx, linux-btrfs@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-ext4@vger.kernel.org, ocfs2-devel@oss.oracle.com,
	linux-mm@kvack.org, ngupta@vflare.org, JBeulich@novell.com,
	kurt.hackel@oracle.com, npiggin@suse.de,
	dave.mccracken@oracle.com, riel@redhat.com, avi@redhat.com,
	konrad.wilk@oracle.com
Subject: Re: [PATCH V2 2/7] Cleancache (was Transcendent Memory): core files
Date: Wed, 02 Jun 2010 17:21:05 -0700	[thread overview]
Message-ID: <4C06F571.3050306@goop.org> (raw)
In-Reply-To: <0be9e88e-7b0d-471d-8d49-6dc593dd43be@default>

On 06/02/2010 05:06 PM, Dan Magenheimer wrote:
> It is intended that there be different flavours but only
> one can be used in any running kernel.  A driver file/module
> claims the cleancache_ops pointer (and should check to ensure
> it is not already claimed).  And if nobody claims cleancache_ops,
> the hooks should be as non-intrusive as possible.
>
> Also note that the operations occur on the order of the number
> of I/O's, so definitely a lot, but "zillion" may be a bit high. :-)
>
> If you think this is a showstoppper, it could be changed
> to be bound only at compile-time, but then (I think) the claimer
> could never be a dynamically-loadable module.
>   

Andrew is suggesting that rather than making cleancache_ops a pointer to
a structure, just make it a structure, so that calling a function is a
matter of cleancache_ops.func rather than cleancache_ops->func, thereby
avoiding a pointer dereference.

    J

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WARNING: multiple messages have this Message-ID (diff)
From: Jeremy Fitzhardinge <jeremy@goop.org>
To: Dan Magenheimer <dan.magenheimer@oracle.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	chris.mason@oracle.com, viro@zeniv.linux.org.uk, adilger@Sun.COM,
	tytso@mit.edu, mfasheh@suse.com, joel.becker@oracle.com,
	matthew@wil.cx, linux-btrfs@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-ext4@vger.kernel.org, ocfs2-devel@oss.oracle.com,
	linux-mm@kvack.org, ngupta@vflare.org, JBeulich@novell.com,
	kurt.hackel@oracle.com, npiggin@suse.de,
	dave.mccracken@oracle.com, riel@redhat.com, avi@redhat.com,
	konrad.wilk@oracle.com
Subject: [Ocfs2-devel] [PATCH V2 2/7] Cleancache (was Transcendent Memory): core files
Date: Thu, 03 Jun 2010 00:21:11 -0000	[thread overview]
Message-ID: <4C06F571.3050306@goop.org> (raw)
In-Reply-To: <0be9e88e-7b0d-471d-8d49-6dc593dd43be@default>

On 06/02/2010 05:06 PM, Dan Magenheimer wrote:
> It is intended that there be different flavours but only
> one can be used in any running kernel.  A driver file/module
> claims the cleancache_ops pointer (and should check to ensure
> it is not already claimed).  And if nobody claims cleancache_ops,
> the hooks should be as non-intrusive as possible.
>
> Also note that the operations occur on the order of the number
> of I/O's, so definitely a lot, but "zillion" may be a bit high. :-)
>
> If you think this is a showstoppper, it could be changed
> to be bound only at compile-time, but then (I think) the claimer
> could never be a dynamically-loadable module.
>   

Andrew is suggesting that rather than making cleancache_ops a pointer to
a structure, just make it a structure, so that calling a function is a
matter of cleancache_ops.func rather than cleancache_ops->func, thereby
avoiding a pointer dereference.

    J

WARNING: multiple messages have this Message-ID (diff)
From: Jeremy Fitzhardinge <jeremy@goop.org>
To: Dan Magenheimer <dan.magenheimer@oracle.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	chris.mason@oracle.com, viro@zeniv.linux.org.uk, adilger@Sun.COM,
	tytso@mit.edu, mfasheh@suse.com, joel.becker@oracle.com,
	matthew@wil.cx, linux-btrfs@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-ext4@vger.kernel.org, ocfs2-devel@oss.oracle.com,
	linux-mm@kvack.org, ngupta@vflare.org, JBeulich@novell.com,
	kurt.hackel@oracle.com, npiggin@suse.de,
	dave.mccracken@oracle.com, riel@redhat.com, avi@redhat.com,
	konrad.wilk@oracle.com
Subject: Re: [PATCH V2 2/7] Cleancache (was Transcendent Memory): core files
Date: Wed, 02 Jun 2010 17:21:05 -0700	[thread overview]
Message-ID: <4C06F571.3050306@goop.org> (raw)
In-Reply-To: <0be9e88e-7b0d-471d-8d49-6dc593dd43be@default>

On 06/02/2010 05:06 PM, Dan Magenheimer wrote:
> It is intended that there be different flavours but only
> one can be used in any running kernel.  A driver file/module
> claims the cleancache_ops pointer (and should check to ensure
> it is not already claimed).  And if nobody claims cleancache_ops,
> the hooks should be as non-intrusive as possible.
>
> Also note that the operations occur on the order of the number
> of I/O's, so definitely a lot, but "zillion" may be a bit high. :-)
>
> If you think this is a showstoppper, it could be changed
> to be bound only at compile-time, but then (I think) the claimer
> could never be a dynamically-loadable module.
>   

Andrew is suggesting that rather than making cleancache_ops a pointer to
a structure, just make it a structure, so that calling a function is a
matter of cleancache_ops.func rather than cleancache_ops->func, thereby
avoiding a pointer dereference.

    J

  reply	other threads:[~2010-06-03  0:21 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-05-28 17:35 [PATCH V2 2/7] Cleancache (was Transcendent Memory): core files Dan Magenheimer
2010-05-28 17:36 ` [Ocfs2-devel] " Dan Magenheimer
2010-05-28 17:35 ` Dan Magenheimer
2010-06-02 19:29 ` Andrew Morton
2010-06-02 19:29   ` [Ocfs2-devel] " Andrew Morton
2010-06-02 19:29   ` Andrew Morton
2010-06-03  0:06   ` Dan Magenheimer
2010-06-03  0:08     ` [Ocfs2-devel] " Dan Magenheimer
2010-06-03  0:06     ` Dan Magenheimer
2010-06-03  0:06     ` Dan Magenheimer
2010-06-03  0:21     ` Jeremy Fitzhardinge [this message]
2010-06-03  0:21       ` [Ocfs2-devel] " Jeremy Fitzhardinge
2010-06-03  0:21       ` Jeremy Fitzhardinge
2010-06-03  2:47       ` Dan Magenheimer
2010-06-03  2:48         ` [Ocfs2-devel] " Dan Magenheimer
2010-06-03  2:47         ` Dan Magenheimer
2010-06-03  2:47         ` Dan Magenheimer
2010-06-10  1:41 ` Nitin Gupta
2010-06-10  1:41   ` [Ocfs2-devel] " Nitin Gupta
2010-06-10  1:41   ` Nitin Gupta
2010-06-10  3:28   ` Dan Magenheimer
2010-06-10  3:29     ` [Ocfs2-devel] " Dan Magenheimer
2010-06-10  3:28     ` Dan Magenheimer
2010-06-10  3:28     ` Dan Magenheimer
  -- strict thread matches above, loose matches on Subject: below --
2010-05-28 17:35 Dan Magenheimer
2010-05-28 17:35 Dan Magenheimer
2010-05-28 17:35 Dan Magenheimer

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