Messages in this thread | | | Date | Thu, 12 Dec 2013 16:51:53 +0100 | From | Peter Zijlstra <> | Subject | Re: 50 Watt idle power regression bisected to Linux-3.10 |
| |
On Thu, Dec 12, 2013 at 07:06:57AM -0800, H. Peter Anvin wrote: > On 12/12/2013 05:28 AM, Ingo Molnar wrote: > >> > >> The reason we use thread_info::flags is because we need to write > >> TIF_NEED_RESCHED into it to wake up anyhow. > >> > >> Using another cacheline would mean the wakeup path would need to write a > >> second cross cpu cacheline -- that is badness too. > >> > >> So no, I don't think we want to listen to another line. > > > > Right, okay, so that's the implicit wakeup. However, I would think the > CLFLUSH would hurt a lot more.
Maybe, but still, who cares? Its only a few broken cpus that actually need the clflush, normal cpus do not. We should not optimize for the broken case.
| |