From: Eric Paris <eparis@redhat.com>
To: John Stoffel <john@stoffel.org>
Cc: linux-kernel@vger.kernel.org,
linux-security-module@vger.kernel.org,
linux-fsdevel@vger.kernel.org, hch@infradead.org,
zohar@us.ibm.com, warthog9@kernel.org, david@fromorbit.com,
jmorris@namei.org, kyle@mcmartin.ca, hpa@zytor.com,
akpm@linux-foundation.org, torvalds@linux-foundation.org,
mingo@elte.hu, viro@zeniv.linux.org.uk
Subject: Re: [PATCH 06/11] IMA: use i_writecount rather than a private counter
Date: Mon, 25 Oct 2010 17:52:37 -0400 [thread overview]
Message-ID: <1288043557.2655.34.camel@localhost.localdomain> (raw)
In-Reply-To: <19653.55831.692904.538148@quad.stoffel.home>
On Mon, 2010-10-25 at 15:27 -0400, John Stoffel wrote:
> The problems with kernel.org is a perfect exmaple of how an annocuous
> feature like this, can kill a system's performance.
You admit that you don't know what you are talking about and then state
that this kills systems performance. Interesting conclusion.
I'm not going to try to refute you point by point but will instead paint
a broad picture. I see 3 possible states:
1) Configured out - 0 overhead. period.
2) Configured in but default disabled
3) Configured in and enabled by admin intervention
I have (I think) pretty clearly discussed the overhead and the changes
made in case #2. We expand struct inode by 4 bytes, we increment and
decrement those 4 bytes on open/close() and we use a new inode->i_flags.
In you e-mail you seemed to be asking about case #3 where you explicitly
chose to load a measurement policy (either custom or using the imb_tcb=1
boot option). There are additional overheads in that case if the inode
in question matches the measurement policy. I don't see the need to go
into the details of that overhead since you have 0 intention of using
this feature no matter what and don't seem to be interested in helping
to change those overheads for users of the subsystem. Please correct me
if I'm wrong. I do readily admit there is overhead, and that overhead
will be higher if inodes which have been deemed integrity relevant by
the measurement policy you chose to load are changed in certain
patterns.
-Eric
next prev parent reply other threads:[~2010-10-25 21:52 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-25 18:41 [PATCH 01/11] IMA: use rbtree instead of radix tree for inode information cache Eric Paris
2010-10-25 18:41 ` [PATCH 02/11] IMA: drop the inode opencount since it isn't needed for operation Eric Paris
2010-10-25 18:41 ` [PATCH 03/11] IMA: use unsigned int instead of long for counters Eric Paris
2010-10-25 18:41 ` [PATCH 04/11] IMA: convert internal flags from long to char Eric Paris
2010-10-25 18:41 ` [PATCH 05/11] IMA: use inode->i_lock to protect read and write counters Eric Paris
2010-10-25 18:41 ` [PATCH 06/11] IMA: use i_writecount rather than a private counter Eric Paris
2010-10-25 19:27 ` John Stoffel
2010-10-25 21:52 ` Eric Paris [this message]
2010-10-25 22:25 ` H. Peter Anvin
2010-10-25 22:29 ` Eric Paris
2010-10-26 13:57 ` John Stoffel
2010-10-26 13:53 ` John Stoffel
2010-10-26 22:08 ` H. Peter Anvin
2010-10-25 18:41 ` [PATCH 07/11] IMA: move read counter into struct inode Eric Paris
2010-10-25 18:42 ` [PATCH 08/11] IMA: only allocate iint when needed Eric Paris
2010-10-25 18:42 ` [PATCH 09/11] IMA: drop refcnt from ima_iint_cache since it isn't needed Eric Paris
2010-10-25 18:42 ` [PATCH 10/11] IMA: explicit IMA i_flag to remove global lock on inode_delete Eric Paris
2010-10-25 18:42 ` [PATCH 11/11] IMA: fix the ToMToU logic Eric Paris
2010-10-25 19:21 ` [PATCH 01/11] IMA: use rbtree instead of radix tree for inode information cache John Stoffel
2010-10-25 19:38 ` J.H.
2010-10-25 20:55 ` Linus Torvalds
2010-10-25 20:57 ` Christoph Hellwig
2010-10-25 21:11 ` Linus Torvalds
2010-10-26 14:01 ` John Stoffel
2010-10-26 15:22 ` Linus Torvalds
2010-10-26 15:30 ` Eric Paris
2010-10-26 15:53 ` John Stoffel
2010-10-26 18:13 ` Al Viro
2010-10-27 13:35 ` James Morris
2010-10-26 14:07 ` John Stoffel
2010-10-25 21:34 ` Eric Paris
2010-10-26 13:45 ` John Stoffel
2010-10-25 23:22 ` Dave Chinner
2010-10-26 0:12 ` Eric Paris
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