[pacman-dev] pacman -Qs first-run performance

[Dan McGee]

On Thu, Sep 1, 2011 at 1:22 PM, Philipp Überbacher
<hollunder at lavabit.com> wrote:
> Excerpts from Dan McGee's message of 2011-09-01 19:54:34 +0200:
>  free -m
>             total       used       free     shared    buffers     cached
> Mem:          2002       1080        922          0         17        299
> -/+ buffers/cache:        763       1239
> Swap:         2055         98       1956
Wow- what are you running on a laptop that is keeping 763 MB of RAM
pegged? Although there appears to be something else in play here.

>  hdparm -Tt /dev/sda
>
> /dev/sda:
>  Timing cached reads:   1426 MB in  2.00 seconds = 712.73 MB/sec
>  Timing buffered disk reads: 166 MB in  3.01 seconds =  55.09 MB/sec
This is a bit slow, but nothing that should impact your performance that much.

>  echo 3 > /proc/sys/vm/drop_caches; time pacman -Qs foobarbaz; time pacman -Qs foobarbaz
>
> real    1m45.235s
> user    0m0.127s
> sys     0m0.590s
>
> real    0m0.097s
> user    0m0.043s
> sys     0m0.023s
Can you repeat this and use /usr/bin/time instead of just plain
"time"? You may have to install the "time" package.
echo 3 > /proc/sys/vm/drop_caches; /usr/bin/time pacman -Qs foobarbaz;
/usr/bin/time pacman -Qs foobarbaz

Once you do that (but please get the numbers first!), try running
`pacman-optimize` then rerunning the above test.

Finally, what is the output of df -h for whatever drive /var/lib is
on? Is it near capacity? And what filesystem with what mount options?

>  echo 3 > /proc/sys/vm/drop_caches; time pacman -Ss foobarbaz; time pacman -Ss foobarbaz
>
> real    0m1.299s
> user    0m0.200s
> sys     0m0.023s
>
> real    0m0.252s
> user    0m0.200s
> sys     0m0.010s

At least this one is OK.

-Dan