Messages in this thread |  | | Subject | Re: [PATCH v3 0/6] powerpc: queued spinlocks and rwlocks | From | Waiman Long <> | Date | Wed, 8 Jul 2020 19:53:04 -0400 |
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On 7/8/20 4:32 AM, Peter Zijlstra wrote: > On Tue, Jul 07, 2020 at 11:33:45PM -0400, Waiman Long wrote: >> From 5d7941a498935fb225b2c7a3108cbf590114c3db Mon Sep 17 00:00:00 2001 >> From: Waiman Long <longman@redhat.com> >> Date: Tue, 7 Jul 2020 22:29:16 -0400 >> Subject: [PATCH 2/9] locking/pvqspinlock: Introduce >> CONFIG_PARAVIRT_QSPINLOCKS_LITE >> >> Add a new PARAVIRT_QSPINLOCKS_LITE config option that allows >> architectures to use the PV qspinlock code without the need to use or >> implement a pv_kick() function, thus eliminating the atomic unlock >> overhead. The non-atomic queued_spin_unlock() can be used instead. >> The pv_wait() function will still be needed, but it can be a dummy >> function. >> >> With that option set, the hybrid PV queued/unfair locking code should >> still be able to make it performant enough in a paravirtualized > How is this supposed to work? If there is no kick, you have no control > over who wakes up and fairness goes out the window entirely. > > You don't even begin to explain... > I don't have a full understanding of how the PPC hypervisor work myself. Apparently, a cpu kick may not be needed.
This is just a test patch to see if it yields better result. It is subjected to further modifcation.
Cheers, Longman
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