bug#44053: Poor profile generation performance on spinning disks

[zimoun]

Hi Maxim,

On Sun, 18 Oct 2020 at 05:37, Maxim Cournoyer <maxim.cournoyer@gmail.com> wrote:

> On my home machine, will is still relying on 2 x 1 TB spinning drives in
> RAID1, rebuilding my user profile, which contains 182 entries, takes on
> average about 20 minutes, even when there are no packages to be built:

The database build time seems correlated to the number of packages in
the very profile.  Well, I have not benchmarked to see if it is
linear, quadratic; or worse or better.


> --8<---------------cut here---------------start------------->8---
[...]
> building XDG MIME database...
> successfully built 
> /gnu/store/cir84qj587i6is4akgqand7ahg9bj938-xdg-mime-database.drv
> successfully built 
> /gnu/store/cir84qj587i6is4akgqand7ahg9bj938-xdg-mime-database.drv
> /gnu/store/j0bznlj2ibnhirijhnwpkkxzz4qfk8wb-xdg-mime-database
>
> real    1m7.344s
> user    0m1.331s
> sys     0m0.053s
> --8<---------------cut here---------------end--------------->8---

Well, it is all clear to me, but I do not know if we can do better
because these 2 XDG updates seem relying on the external binaries
"/bin/update-desktop-database" and "/bin/update-mime-database".  I
have not timed the function 'xdg-desktop-database' but all the time
should be spent on these, I bet. :-)


All the best,
simon