On 27. 5. 2013 at 09:43:15, Florian Weimer wrote: > On 05/27/2013 09:32 AM, Jan Zelený wrote: > > On 25. 5. 2013 at 09:34:32, Nico Kadel-Garcia wrote: > >> On Wed, May 22, 2013 at 11:55 AM, Michael Ekstrand <michael@xxxxxxxxxxx> > > > > wrote: > >>> Performance improvement: improve scaling to 5K+ installed packages. > >> > >> * Amen. This is particularly compounded by poor caching default > >> behavior, so that a few yum commands in a row each wind up reaching > >> out to downloading metadata again, and again, and again. > >> > >> I think this can be addressed by moving the metadata updates to a > >> different function, and calling it *separately* only as needed. The > >> Debian "apt" tool does this quite effectively. > > > > Unfortunately there is not much we can do about this. Debian has > > completely > > different repository policy - they keep all versions of packages in the > > repo so there is no need to update metadata on client machines every > > time. > I don't quite understand this comment. > > Debian repository policy varies quite a bit. Some repositories keep old > versions, some don't. Mostly the latter, actually, because not all > repository managers (there a couple of implementations) can deal with > multiple versions for a single package/architecture combination. I'm sorry but the Debian repositories say otherwise, see Iceweasel for instance: http://ftp.cz.debian.org/debian/pool/main/i/iceweasel/ Multiple old versions are kept in there. That's why they don't need to update their metadata every single time - the old ones are simply still valid. > As far as I can tell, the main difference is that apt-get and apt-cache > read very few, relatively large files at the beginning, so they don't > block on disk reads early. > > dpkg, on the other hand, uses a database scatter across many small files > on disk, so you get the delay only when you actually install or remove > any packages. At the beginning, this is quite fast, but eventually, the > files will be scattered quite badly, and there is a considerable delay > at this step. This part is about disk read-write but that was not what I was writing about. >From my experience users mostly complain about the metadata download which is explained above. Thanks Jan -- devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxxx https://admin.fedoraproject.org/mailman/listinfo/devel
