DNF5 delayed

Posted Aug 21, 2023 18:11 UTC (Mon) by Sesse (subscriber, #53779)
In reply to: DNF5 delayed by mbunkus
Parent article: DNF5 delayed

> If each invocation of dpkg reads the whole database, that should not take a lot of time safe for the first time — assuming reading is done with some proper chunking (meaning only do a handful of big read calls, allowing for I/O speed).

How can you do a handful of big read calls to read thousands of files? There's one for each package installed.

> The next invocation should then get the whole database's data from the kernel's caches, shouldn't it?

Parsing 600000+ lines of text (example number from my laptop) takes real CPU time, even if the I/O is free or nearly so.

DNF5 delayed

Posted Aug 21, 2023 18:19 UTC (Mon) by mbunkus (subscriber, #87248) [Link]

> How can you do a handful of big read calls to read thousands of files? There's one for each package installed.

Ooooh I didn't know that. I thought it only reads the files directly in /var/lib/dpkg, not all the .list files, too. Good to know! I agree, that seems like a rather inefficient way to handle the information.