Messages in this thread | | | Date | Tue, 21 Aug 2012 20:12:55 +0100 | From | Ben Hutchings <> | Subject | Re: Using random in interrupts for RT |
| |
On Tue, Aug 21, 2012 at 02:12:13PM -0400, Steven Rostedt wrote: > On Tue, 2012-08-14 at 10:30 -0400, Steven Rostedt wrote: > > Thomas, > > > > Ben Hutchings asked me if we still need "genirq: Disable random call on > > preempt-rt" for -rt? With commit 902c098a366 "random: use lockless > > techniques in the interrupt path" there is no more locks used. But does > > it still produce high latencies? > > Ben, > > Looks that the #ifndef can't be removed just yet. The code is not > totally lockless... > > > add_interrupt_randomness -> > credit_entropy_bits -> > kill_fasync -> > kill_fasync_rcu -> > spin_lock_irqsave(&fa->fa_lock, flags) > > to make things worse, that spinlock turns into a mutex on -rt, so it may > crash the box if triggered.
Thanks for checking this.
Ben.
-- Ben Hutchings We get into the habit of living before acquiring the habit of thinking. - Albert Camus
| |