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From: "H. Peter Anvin" <hpa@zytor.com>
To: Eric Paris <eparis@redhat.com>
Cc: John Stoffel <john@stoffel.org>,
	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, 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 15:25:39 -0700	[thread overview]
Message-ID: <4CC603E3.3070405@zytor.com> (raw)
In-Reply-To: <1288043557.2655.34.camel@localhost.localdomain>

On 10/25/2010 02:52 PM, Eric Paris wrote:
> 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.
> 

Case #2 is the bad one, as long as distros are likely to compile it in.

	-hpa

  reply	other threads:[~2010-10-25 22:27 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
2010-10-25 22:25       ` H. Peter Anvin [this message]
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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