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Groups > linux.kernel > #1381381
| From | Xunlei Pang <xpang@redhat.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH v3 1/6] rtmutex: Deboost before waking up the top waiter |
| Date | 2016-04-18 10:50 +0200 |
| Message-ID | <rpd2x-2oe-11@gated-at.bofh.it> (permalink) |
| References | <rnNMR-Ww-3@gated-at.bofh.it> <rnNMS-Ww-23@gated-at.bofh.it> <rpcJc-2fT-17@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On 2016/04/18 at 16:23, Thomas Gleixner wrote: > On Thu, 14 Apr 2016, Xunlei Pang wrote: >> We should deboost before waking the high-prio task such that >> we don't run two tasks with the 'same' priority. > No. This is fundamentaly broken. > > T1 (prio 0) lock(X) > > --> preemption > > T2 (prio 10) lock(X) > boost(T1) > schedule() > > T1 (prio 10) unlock(X) We add a preempt_disable() before deboost to avoid the breakage, there's also some comment about this in the patch's code. Regards, Xunlei > deboost() > (prio 0) > > --> preemption > > T3 (prio 5) .... > > Classic priority inversion enabled by a mechanism to avoid it. Brilliant > stuff. > > Thanks, > > tglx
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Re: [PATCH v3 1/6] rtmutex: Deboost before waking up the top waiter Thomas Gleixner <tglx@linutronix.de> - 2016-04-18 10:30 +0200
Re: [PATCH v3 1/6] rtmutex: Deboost before waking up the top waiter Xunlei Pang <xpang@redhat.com> - 2016-04-18 10:50 +0200
Re: [PATCH v3 1/6] rtmutex: Deboost before waking up the top waiter Thomas Gleixner <tglx@linutronix.de> - 2016-04-18 11:10 +0200
Re: [PATCH v3 1/6] rtmutex: Deboost before waking up the top waiter Xunlei Pang <xpang@redhat.com> - 2016-04-18 11:50 +0200
Re: [PATCH v3 1/6] rtmutex: Deboost before waking up the top waiter Peter Zijlstra <peterz@infradead.org> - 2016-04-20 14:30 +0200
Re: [PATCH v3 1/6] rtmutex: Deboost before waking up the top waiter Thomas Gleixner <tglx@linutronix.de> - 2016-04-20 14:50 +0200
Re: [PATCH v3 1/6] rtmutex: Deboost before waking up the top waiter Peter Zijlstra <peterz@infradead.org> - 2016-04-20 15:20 +0200
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