Re: [PATCH 1/3] IMA: move read/write counters into struct inode

[Eric Paris]

On Wed, 2010-10-20 at 17:15 +0200, Ingo Molnar wrote:
> * Eric Paris <eparis@xxxxxxxxxx> wrote:
> 
> > On Wed, 2010-10-20 at 16:38 +0200, Ingo Molnar wrote:
> > > * Eric Paris <eparis@xxxxxxxxxx> wrote:
> > > 
> > > > Executive summary of the day's work:
> > > > Yesterday morning: 944 bytes per inode in core
> > > > Yesterday night: 24 bytes per inode in core
> > > > Tonight: 4 bytes per inode in core.
> > > > 
> > > > That's a x236 time reduction in memory usage.  No I didn't even start looking 
> > > > at a freezer.  Which could bring that 4 down to 0, but would add a scalability 
> > > > penalty on all inodes when IMA was enabled.
> > > 
> > > Why not use inode->i_security intelligently? That already exists so that way 
> > > it's 0 bytes.
> > > 
> > > Thanks,
> > 
> > It still wouldn't be 0 bytes since there would be a 1-1 mapping from inode to 
> > i_security structs. [...]
> 
> Only for IMA-affected files, right?

No, we need to keep the open read counter even for non-IMA-affected
files in case we later determine that it is IMA-affected.  That's the 4
bytes I have today, which I said could be eliminated with a freezer that
calculated it when IMA was enabled, but isn't something I'm looking at
right now....

-Eric

-Eric

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