Messages in this thread | | | Date | Thu, 14 Dec 2017 20:48:53 +0100 | From | Peter Zijlstra <> | Subject | Re: [RFC PATCH for 4.16 02/21] rseq: Introduce restartable sequences system call (v12) |
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On Thu, Dec 14, 2017 at 12:50:13PM -0600, Christopher Lameter wrote: > Ultimately I wish fast increments like done by this_cpu_inc() could be > implemented in an efficient way on non x86 platforms that do not have > cheap instructions like that.
So the problem isn't migration; for that we could wrap the operation in preempt_disable() which is not more expensive than rseq would be. And a lot more deterministic.
The problem instead is interrupts, which can result in nested load-store operations, and that comes apart. This then means having to disable interrupts over these things and _that_ is expensive.
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