Re: [RFC][PATCH v1 5/9] ima: allocating iint improvements

From: Eric Paris
Date: Wed Feb 01 2012 - 11:58:55 EST

On Mon, Jan 30, 2012 at 5:14 PM, Mimi Zohar <zohar@xxxxxxxxxxxxxxxxxx> wrote:
> From: Dmitry Kasatkin <dmitry.kasatkin@xxxxxxxxx>

>  static struct rb_root integrity_iint_tree = RB_ROOT;
> -static DEFINE_SPINLOCK(integrity_iint_lock);
> +static DEFINE_RWLOCK(integrity_iint_lock);
>  static struct kmem_cache *iint_cache __read_mostly;

Has any profiling been done here? rwlocks have been shown to
actually be slower on multi processor systems in a number of cases due
to the cache line bouncing required. I believe the current kernel
logic is that if you have a short critical section and you can't show
profile data the rwlocks are better, just stick with a spinlock.
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