On 11/9/21 7:46 AM, Stephen John Smoogen wrote: > On Tue, 9 Nov 2021 at 04:39, Rajeesh K V <rajeeshknambiar@xxxxxxxxx> wrote: >> >>>> I remember seeing 60-70% reduction really often, and 90+ periodically. I've >>>> read Kevin's explanation of why it's not working as well now, but I wonder >>>> what changed between the early implementation when results were very good >>>> and now, when they really aren't. >>> >>> I think it's because you only see deltas from N to N+1 now and before >>> you saw deltas from N to N+X before. So, I think if we made it somehow >>> create older deltas, you would again see better savings. The issue >>> doesn't just cause there to be fewer deltas, but it also causes those >>> few be be against very recent changes, so less effective. >> >> Would it make sense (and possible to implement fairly easily) to >> generate deltas weekly instead of daily? That may already be a good >> start; as I’d imagine bandwidth constrained users would generally try >> to update on a weekly or monthly basis. > > Not easily for 2 reasons: > > 1. deltas are package to package and many packages rev 4-6 times a > week (I am looking at you, kernel). So a once a week delta update > would have to make deltas against each of those packages for both > people who are resource constrained and those who are not. > 2. Each 'compose' of Fedora is like a manufacturing line where if you > turn off some part, the rest after that point break because something > they expect is not there. If we turn off deltas altogether, we can > clean up various bits that were expected afterwards but someone would > need to do that work while doing all the usual work. > > So you would need to set up a seperate compose pipeline which would do > this once a week and put those in a tree which is distinct from the > regular daily Fedora. That requires doubling the number of servers and > increasing disk space. Both of which are limited resources on the part > of Fedora Infrastructure. Would it be possible to just stop making deltarpms entirely and disable them outright? It appears that this would save a significant amount of resources on the Fedora side, and they increase the attack surface of all Fedora users who do not disable them. Sincerely, Demi Marie Obenour (she/her/hers)
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