On Fri, 9 Dec 2016, Samuel Just wrote: > Currently, never. However, I'm thinking that we might want to retain > the freedom to not send the structure if it's really big. And > actually, we won't ever need to extend a received past_intervals > structure to the current epoch since if the interval changed, we'd > throw out the whole message. I'd say throw out the incremental build code, then, and assert past_intervals is present at notify time; we can re-add something to recalculate the whole past_intervals if it becomes necessary in the future. sage > -Sam > > On Fri, Dec 9, 2016 at 2:16 PM, Sage Weil <sweil@xxxxxxxxxx> wrote: > > On Fri, 9 Dec 2016, Samuel Just wrote: > >> In particular, we don't need PG::generate_past_intervals duplicating > >> the logic in build_past_intervals_parallel since constructed PG > >> objects only ever need to maintain a consistent past_intervals > >> structure, never build it from scratch. > > > > Sounds good to me. > > > > My main question is: > > > >> On Fri, Dec 9, 2016 at 11:59 AM, Samuel Just <sjust@xxxxxxxxxx> wrote: > >> > There's code for dealing with some odd past_intervals configurations > >> > including doesn't go back far enough and doesn't go forward far > >> > enough. I *think* we can simplify this as follows: > >> > 1) Once the PG object is constructed and in memory, past_intervals > >> > extends from history.last_epoch_started to the PG's current map > >> > 2) On disk, either 1) is true or the set is empty (after an import) > >> > > >> > On boot, the OSD generates past_intervals in parallel for any PGs > >> > without them (and perhaps verifies 1) for the rest). On receipt of a > >> > Notify creating a PG, the OSD generates the past_intervals structure > >> > before instantiating the PG using the same process as on boot -- > >> > starting with the included past_intervals if present (may not extend > >> > to the current map, and so may need to be extended). > > > > When does this actually happen? If PGs are always in state 1, can we > > instead ensure that PG notify will always include past_intervals and that > > a received notify will never require us to go off do the (slow) work of > > loading up old maps to generate old intervals? > > > > Then, we can focus our efforts on make the past_intervals representation > > compact (e.g., by discarding redundant intervals)... > > > > sage > -- > To unsubscribe from this list: send the line "unsubscribe ceph-devel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > > -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
