Re: [PATCH 0/6] support "dataplane" mode for nohz_full
From: Chris Metcalf <hidden>
Date: 2015-05-11 19:25:38
Also in:
lkml
On 05/11/2015 03:19 PM, Mike Galbraith wrote:
I really shouldn't have acked nohz_full -> isolcpus. Beside the fact that old static isolcpus was_supposed_ to crawl off and die, I know beyond doubt that having isolated a cpu as well as you can definitely does NOT imply that said cpu should become tickless.
True, at a high level, I agree that it would be better to have a top-level concept like Frederic's proposed ISOLATION that includes isolcpus and nohz_cpu (and other stuff as needed). That said, what you wrote above is wrong; even with the patch you acked, setting isolcpus does not automatically turn on nohz_full for a given cpu. The patch made it true the other way around: when you say nohz_full, you automatically get isolcpus on that cpu too. That does, at least, make sense for the semantics of nohz_full. -- Chris Metcalf, EZChip Semiconductor http://www.ezchip.com