[dm-devel] [PATCH] backing-dev: use synchronize_rcu_expedited instead of synchronize_rcu
Paul E. McKenney
paulmck at linux.vnet.ibm.com
Fri Feb 3 00:29:02 UTC 2012
On Thu, Feb 02, 2012 at 10:59:04PM +0100, Peter Zijlstra wrote:
> On Thu, 2012-02-02 at 15:43 -0500, Mikulas Patocka wrote:
> > Do you have some measurable use case where the user is removing block
> > devices so heavily that this causes a problem?
>
> Even one can be a problem, we're having people spend lots of time and
> effort to reduce machine wide jitter and interference. Adding it with
> such disregard isn't cool.
>
> There's no reason a management cpu adding or removing block devices
> should perturb the high-freq trading or industrial laser control running
> on the other side of the machine.
Very true for real-time applications!
For the heavy trading apps, given Frederic's upcoming user-mode-idle work,
I can keep this stuff from perturbing the apps. Still, batching would
be preferable.
Thanx, Paul
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