[Aptitude-devel] apt vs. SSD computers

[Axel Beckert]

Hi,

[Removing debian-mirrors at l.d.o, but adding in
aptitude-devel at l.alioth.d.o instead of aptitude at p.d.o as Bob's mail
never reached the aptitude maintainers as far as I can see.]

Bob Proulx wrote:
> > $ vmstat -n 2
> > procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu----
> >  r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa
> >  0  0      0 483308  25596 408892    0    0     0     0   46  125  0  1 99  0
> >  1  0      0 478412  25596 408892    0    0     0     0  156  173 23  2 76  0
> >  0  1      0 459580  25608 432576    0    0     0  1854  330  144 42 13  0 45
> >  0  1      0 459340  25616 432576    0    0     0  2406  102  125  0  1  0 99
> >  0  1      0 459216  25620 432576    0    0     0  2280  101  125  1  2  0 98
> > ...
> 
> The si/so values all look okay.  So that refutes my hypothesis that
> the machine was swapping.

Yeah, aptitude doesn't need _that_ much RAM. I run it without swapping
on boxes with 512 MB and even less.

> And 1G of ram should be sufficient too.

Definitely.

> > OK, Bob, (sorry Otto) here's what happens when we hit Y to aptitude's
> > 
> > "No packages will be installed, upgraded, or removed.
> > 0 packages upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
> > Need to get 0 B of archives. After unpacking 0 B will be used.
> > Do you want to continue? [Y/n/?]"
> > 
> > Which is the slowest thing I can recreate today.
> > (It takes 28 seconds to do one big no-op.)

Same here (EeePC 701, 680 MHz, 2 GB of RAM):

aptitude full-upgrade  17.87s user 3.23s system 75% cpu 27.927 total

(Fine for me though. I've got far slower boxes on which I run aptitude
and are still happy with it. Of course I wouldn't mind if it would be
faster though. :-)

> I find aptitude to be extremely slow on any machine.

Depends. It get's annoyingly slow due to swapping below 64 MB of RAM.
But above, it's IMHO generally fine for what it does. Nevertheless at
32 MB of RAM, apt-get isn't really faster either nowadays. I guess
that's mostly because of the impressively big choice Debian offers
nowadays.

> Your 900MHz 1G ram Asus EEE PC 702 is going to struggle with it.

I wouldn't call that struggle.

> I don't have anything exactly the same but I do have an 866MHz
> Pentium 3 machine with 256M ram here as the closest match and here
> are the timings from it. I ran each twice to show that the cache was
> warmed up for each.
> 
>   # time apt-get upgrade
>   real    0m1.383s
>   user    0m1.360s
>   sys     0m0.020s
> 
>   # time apt-get upgrade
>   real    0m1.389s
>   user    0m1.344s
>   sys     0m0.036s
> 
>   # time aptitude upgrade
>   real    0m11.219s
>   user    0m9.041s
>   sys     0m0.720s
> 
>   # time aptitude upgrade
>   real    0m12.026s
>   user    0m9.053s
>   sys     0m0.684s
>
[...]
> As you can see from this data it will perform a lot better on your
> machine.

Sure it does. On every machine. That's a long time secret, see e.g.
http://bugs.debian.org/270909 and http://bugs.debian.org/519906 -- And
hey, guess from who both these bug reports are? I think I recognize a
pattern there... Maybe it's just jidanni who thinks that aptitude is
slow. ;-)

But seriously, there are also some comments and ideas about improving
aptitude startup performance in
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=693144#32

> Try apt-get instead of aptitude.

That's not the point. apt-get and aptitude have different feature
sets. You don't use aptitude just because it has the nicer name. You
use aptitude because you want some of the features aptitude has and
apt-get hasn't. (If you don't, please consider using apt-get only. :-)

		Regards, Axel
-- 
 ,''`.  |  Axel Beckert <abe at debian.org>, http://people.debian.org/~abe/
: :' :  |  Debian Developer, ftp.ch.debian.org Admin
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