Messages in this thread | | | Date | Thu, 5 Jan 2017 13:50:20 -0500 | From | Steven Rostedt <> | Subject | Re: [RFC PATCH 0/7] locking/rtqspinlock: Realtime queued spinlocks |
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On Thu, 5 Jan 2017 12:07:21 -0500 Waiman Long <longman@redhat.com> wrote:
> I do make the assumption that spinlock critical sections are behaving > well enough. Apparently, that is not a valid assumption. I sent these > RFC patches out to see if it was an idea worth pursuing. If not, I can > drop these patches. Anyway, thanks for the feedback.
Yes, the assumption is incorrect. There are places that can hold a spin lock for several hundreds of microseconds. If you can't preempt them, you'll never get below several hundreds of microseconds in latency.
And it would be hard to pick and choose (we already do this to decide what can be a raw_spin_lock), because you need to audit all use cases of a spin_lock as well as all the locks taken while holding that spin_lock.
-- Steve
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