drago01 <drago01 <at> gmail.com> writes:
Here it went up from 1.2MB/s to 2.1-2.6MB/s (4 cores - 8 threads). Not sure how many threads it actually uses but this is not a linear speedup. Disk is an SSD as well.
I asked Jonathan Dieter about the speedup in the bug and he responded in https://bugzilla.redhat.com/show_bug.cgi?id=701711#c13 . I was aware that applydeltarpm itself is not threaded (which is probably not feasible, at least with any hope of a linear speedup) and that yum-presto instead runs multiple instances of it in different threads. To get a linear speedup, you'd need both for I/O not to be an issue, and for there to be enough drpms to keep all N cores busy simultaneously. If there are only a few drpms, or some are much larger than others, that won't happen. Of course, it's good to do updates often, but that means relatively few drpms each time. Not as good as I expected, unfortunately.