Re: [PATCH 06/11] IMA: use i_writecount rather than a private counter

[H. Peter Anvin]

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
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