Messages in this thread | | | Date | Mon, 16 Apr 2018 10:02:41 -0700 | From | Andi Kleen <> | Subject | Re: [RFC PATCH for 4.18 12/23] cpu_opv: Provide cpu_opv system call (v7) |
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> Single-stepping is only a subset of the rseq limitations addressed > by cpu_opv. Anoher major limitation is algorithms requiring data > migration between per-cpu data structures safely against CPU hotplug, > and without having to change the cpu affinity mask. This is the case
And how many people are going to implement such a complex separate path just for CPU hotplug? And even if they implement it how long before it bitrots? Seems more like a checkbox item than a realistic approach.
> for memory allocators and userspace task schedulers which require > cpu_opv for migration between per-cpu memory pools and scheduler > runqueues.
Not sure about that. Is that common?
> > About the vgettimeofday and general handling of vDSO by gdb, gdb's > approach only takes care of line-by-line single-stepping by hiding > Linux' vdso mapping so users cannot target source code lines within > that shared object. However, it breaks instruction-level single-stepping. > I reported this issue to you back in Nov. 2017: > https://lkml.org/lkml/2017/11/20/803
It was known from day 1, but afaik never a problem.
-Andi
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