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From: "Kasatkin, Dmitry" <dmitry.kasatkin@intel.com>
To: Eric Paris <eparis@parisplace.org>
Cc: Mimi Zohar <zohar@linux.vnet.ibm.com>,
	linux-security-module@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	David Safford <safford@watson.ibm.com>,
	Mimi Zohar <zohar@us.ibm.com>
Subject: Re: [RFC][PATCH v1 5/9] ima: allocating iint improvements
Date: Wed, 1 Feb 2012 20:46:54 +0200	[thread overview]
Message-ID: <CALLzPKZcr8fZ9-VXqLHN=H69+GOnp48CjZX+xxmBBksbmJsLxw@mail.gmail.com> (raw)
In-Reply-To: <CACLa4ptFgmCL7Z4e-YO9XJ_zkr=kOHSJ7cA8u3DPvVc-2LBfRw@mail.gmail.com>

On Wed, Feb 1, 2012 at 6:58 PM, Eric Paris <eparis@parisplace.org> wrote:
> On Mon, Jan 30, 2012 at 5:14 PM, Mimi Zohar <zohar@linux.vnet.ibm.com> wrote:
>> From: Dmitry Kasatkin <dmitry.kasatkin@intel.com>
>>
>
>>  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.

No, I have not done any profiling.
My assumption was that rwlocks are better when there many readers.
If what you say is true then rwlocks are useless...
With big sections it is necessary to use rw semaphores.

- Dmitry

  reply	other threads:[~2012-02-01 18:46 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-01-30 22:13 [RFC][PATCH v1 0/9] ima: appraisal extension Mimi Zohar
2012-01-30 22:13 ` [RFC][PATCH v1 1/9] vfs: extend vfs_removexattr locking Mimi Zohar
2012-01-30 22:13 ` [RFC][PATCH v1 2/9] vfs: move ima_file_free before releasing the file Mimi Zohar
2012-01-30 22:13 ` [RFC][PATCH v1 3/9] ima: integrity appraisal extension Mimi Zohar
2012-01-30 22:13 ` [RFC][PATCH v1 4/9] ima: add appraise action keywords and default rules Mimi Zohar
2012-01-30 22:14 ` [RFC][PATCH v1 5/9] ima: allocating iint improvements Mimi Zohar
2012-02-01 16:58   ` Eric Paris
2012-02-01 18:46     ` Kasatkin, Dmitry [this message]
2012-02-09  9:40       ` Kasatkin, Dmitry
2012-01-30 22:14 ` [RFC][PATCH v1 6/9] ima: add inode_post_setattr call Mimi Zohar
2012-01-30 22:14 ` [RFC][PATCH v1 7/9] ima: add ima_inode_setxattr/removexattr function and calls Mimi Zohar
2012-01-30 22:14 ` [RFC][PATCH v1 8/9] ima: add support for different security.ima data types Mimi Zohar
2012-01-30 22:14 ` [RFC][PATCH v1 9/9] ima: digital signature verification support Mimi Zohar

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