On Thu, Jan 30, 2020 at 05:05:28PM -0500, Alex Kogan wrote:

quoted

On Jan 25, 2020, at 6:19 AM, Peter Zijlstra [off-list ref] wrote:

On Fri, Jan 24, 2020 at 01:19:05PM -0500, Alex Kogan wrote:

quoted

Is there a lightweight way to identify such a “prioritized” thread?

No; people might for instance care about tail latencies between their
identically spec'ed worker tasks.

I would argue that those users need to tune/reduce the intra-node handoff
threshold for their needs. Or disable CNA altogether.

I really don't like boot time arguments (or tunables in generic) for a
machine to work as it should.

The default really should 'just work'.

In general, Peter, seems like you are not on board with the way Longman
suggested to handle prioritized threads. Am I right?

Right.

Presumably you have a workload where CNA is actually a win? That is,
what inspired you to go down this road? Which actual kernel lock is so
contended on NUMA machines that we need to do this?

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