On Sat, Oct 22, 2016 at 02:15:01AM +0800, Chi-Hsuan Yen via arch-general wrote: > On Sat, Oct 22, 2016 at 1:54 AM, Robin via arch-general < > arch-general@xxxxxxxxxxxxx> wrote: > > > Hi, > > > > > I was curious why does 'pacman -Q' operations took longer than 'apt' > > > counterparts. > > Sounds interesting but I have a few question about how did you measure > > this and how big the difference is. (Shouldn't be that big). Would be great > > if you provide more information on the comparability of you systems and the > > tools you used for tracing. > > Maybe there are other reasons why it is slow on your installation ? > > > > > For long term pacman development road map, it would be better to use > > > single sql based database for tracking locally installed packages > > > instead of keeping directories of every installed packages. > > I am not sure if a sql based database would be a good solution if you > > where right. It adds much more complexity and also a dependencies on $SQL > > backend. For me as a semi-professional arch user this would be worse than a > > maybe "not that fast" package dB querying. > > > > Regards, > > Robin > > > Sometimes I have a similar problem, too. When the system just boots up, or > I just exploits my disk (for example building Firefox), pacman-related > files are moved out of the disk cache, so it needs some time to read them > all from the disk. Here's a simple performance test: > > $ sudo -v && time pacman -Q linux && sudo sync && sudo sync && echo 3 | > sudo tee /proc/sys/vm/drop_caches && time pacman -Q linux > [sudo] password for yen: > linux 4.8.3-1 > pacman --color=auto -Q linux 0.00s user 0.00s system 2% cpu 0.121 total > 3 > linux 4.8.3-1 > pacman --color=auto -Q linux 0.00s user 0.01s system 0% cpu 1.229 total > > The difference is more than 10 times. I use a 5-year-old HDD. I guess on > even older machines things are worse. > > Regards, > > Yen Chi Hsuan My own test - before optimization, ``pacman -Qs linux`` took almost half a minute. $ time pacman -Qs linux real 0m26.716s user 0m0.063s sys 0m0.230s After running ``pacman-optimize``, it runs instantly. $ time pacman -Qs linux real 0m0.048s user 0m0.030s sys 0m0.017s The filesystem fragmentation can be felt more deeply on slower and older HDD.
