Messages in this thread | | | Date | Wed, 3 Aug 2016 13:29:35 -0500 (CDT) | From | Christoph Lameter <> | Subject | Re: [RFC PATCH v7 1/7] Restartable sequences system call |
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On Tue, 26 Jul 2016, Mathieu Desnoyers wrote:
> > What problem does this solve? > > It allows user-space to perform update operations on per-cpu data without > requiring heavy-weight atomic operations.
This is great but seems to indicate that such a facility would be better for kernel code instread of user space code.
> First, prohibiting migration from user-space has been frowned upon > by scheduler developers for a long time, and I doubt this mindset will > change.
Note that the task isolation patchset from Chris Metcalf does something that goes a long way towards this. If you set strict isolation mode then the kernel will terminate the process or notify you if the scheduler becomes involved. In some way we are getting that as a side effect.
Also prohibiting migration is trivial form user space. Just do a taskset to a single cpu.
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