On Wed, Apr 24, 2019 at 01:12:04PM +0200, Sebastian Andrzej Siewior wrote: > The swap code synchronizes its access to the (four) pagevec struct > (which is allocated per-CPU) by disabling preemption. This works and the > one struct needs to be accessed from interrupt context is protected by > disabling interrupts. This was manually audited and there is no lockdep > coverage for this. > There is one case where the per-CPU of a remote CPU needs to be accessed > and this is solved by started a worker on the remote CPU and waiting for > it to finish. > > In v1 [0] it was attempted to add per-CPU spinlocks for the access to > struct. This would add lockdep coverage and access from a remote CPU so > the worker wouldn't be required. >From my point of view, what is missing from this description is why we want to be able to access these structs from a remote CPU. It's explained a little better in the 4/4 changelog, but I don't see any numbers that suggest what kinds of gains we might see (eg "reduces power consumption by x% on a particular setup", or even "average length of time in idle extended from x ms to y ms").
