Hi Peter, On Wed, Aug 11, 2021 at 6:12 AM Peter Xu <peterx@xxxxxxxxxx> wrote: > > On Tue, Aug 10, 2021 at 06:06:51PM -0700, Mingwei Zhang wrote: > > Regarding the pursuit for accuracy, I think there might be several > > reasons. One of the most critical reasons that I know is that we need > > to ensure dirty logging works correctly, i.e., when dirty logging is > > enabled, all huge pages (both 2MB and 1GB) _are_ gone. Hope that > > clarifies a little bit? > > It's just for statistics, right? I mean dirty log should be working even > without this change. That's true. What I meant was that the accurate stats might be able to help verifying a property of dirty logging as a side benefit. Sorry for the confusion. > > But I didn't read closely last night, so we want to have "how many huge pages > we're mapping", not "how many we've mapped in the history". Yes that makes > sense to be accurate. I should have looked more carefully, sorry. > > PS: it turns out atomic is not that expensive as I thought even on a 200 core > system, which takes 7ns (but for sure it's still expensive than normal memory > ops, and bus locking); I thought it'll be bigger as on a 40 core system I got > 15ns which is 2x of my laptop of 8 cores, but it didn't really grow but shrink. Thanks for the information about atomic access! > > Thanks, > > -- > Peter Xu >
