[Digikam-users] New computer for Digikam

[Gilles Caulier]

2007/12/8, Gerhard Kulzer <gerhardkgmx at gmail.com>:
>
> Am Saturday 08 December 2007 schrieb Dotan Cohen:
> > On 08/12/2007, Mikolaj Machowski <mikmach at wp.pl> wrote:
> > > Dnia Saturday 08 of December 2007, Dotan Cohen napisał:
> > > > I am considering replacing an aging desktop computer. The machine is
> > > > used mostly for Digikam, Amarok, and Kopete. Only occasionally are
> > > > other apps, such as K3B, Firefox, Skype, and Open Office ever used.
> > > > Therefore, I want a system that is tuned best for Digikam.
> > >
> > > digiKam can only gain from faster disks, memory and processor. Next
> > > version of KDE can gain from better graphic card due to increase usage
> > > of OpenGL effects but I am not aware about usage of those in digiKam
> > > - now or in near future (apart from slideshows).
> >
> > Thanks, Mikolaj. I just wanted to know where I should be careful not
> > to bottleneck. A 3.6 GHz processor would be a waste if the system had
> > only 256MB RAM (extreme example).
> >
> > Do factors such as bus speed, L2 cache, number of cores, and speed of
> > RAM make a significant difference for Digikam specifically? I know
> > that it seems like a silly question, but if I'm buying hardware for a
> > specific purpose, I'd like to get the right hardware. And I _will_
> > have to make compromises as budget allows. Where should those
> > compromises be?
> >
> > Thanks.
> >
> > Dotan Cohen
> >
> Right now digiKam is not yet taking much advantage of smp for the
> heavy-load
> plugins (CIMG), but that will change in the future, so a dual processor is
> recommended, although not fully exploited today. There are a lot of tasks
> running in threads by now, but those are not the time consumers. If you
> planned for today only, a fast single CPU would be better, but I don't
> recommend it. Don't buy a dual core machine that is too slow in clock.


I'm not agree. A dual core is a 2 processors in same core.

DigiKam use multithreading everywhere when it's possible : compute or
loading image for ex.

With a dual core, the main thread (GUI) will run on first processor, and
child thread will run on second processor. if clock speed is more slow than
a fast single core processor, there is a real advantage to fork sub-tasks on
a separate processor...

 Currently, CImg based plugins use 2 sub-threads to work. This is perfectly
adapted to dual core...

I always recommend to use :

- Intel processor instead AMD (Gcc give better result especially about
speed)
- 32 bits processors. 64 bits is a mess under Linux. 64 bits library need to
use a 32 bits emulation like to run...

In my office, we have 3 bigs computers using 48 / 64 / and 128 processors
and running under linux. It's used by physicians to calc thermonuclear
reaction simulation codes...

The first one is an old Alpha processor based computer. Very fast
The second one an AMD 64 bits processor.
The third is a 32 bits Intel based processor.

The AMD based give less speed result than Alpha and Intel computer.

Gilles

Intels
> can be overclocked, but you need the MB that goes with it. L2 cache is
> quite
> important in my experience. Two cores is fantastic even if you don't run
> many
> applications in parallel. I just enjoy my machine churning on digiKam
> stuff
> and still be reactive as nothing would happen in the background :-), it's
> impressive.
> My CPU recommendation is Intel E6750, that is really cheap for what it is,
> cheaper than slower CPUs. But you need an 1333MHz FSB motherboard. I'd
> recommend that anyway, because if you want to upgrade later, the CPUs are
> likely to run at least that fast (I just sold my E6400 CPU on ebay for 98%
> of
> the price I bought it a year ago, upgrading is possible).
> Buy enough memory, 1GB is not enough, buy >=2GB. The memory speed is not
> so
> important, between the slow ones and fast one there is hardly 10%
> difference
> in endperformance.
> SATA or ATA, my hdparm tests don't show much of a difference. But modern
> MB
> will oblige you to go SATA-II. The file system makes more of a diff, not
> for
> saving the images, but for the thumbnails caching. Mount them with
> 'noatime'.
> Without journal is much faster. Better is (you seem to have two disks) to
> put
> the journal of one disk on the other drive. Speed is then as a fs without
> journaling because of the parallel access. xfs, reiserfs or ext3 are all
> good.


I have always use reiser FS under Linux. It's probably the best...


digiKam don't ask much of graphic cards. But nowadays even good ones are
> cheap, I bought a nvidia NT8600GT for less than 100 euros, has 260MB RAM,
> passively cooled. And I wouldn't want to miss compiz anymore.
> Think rather of a good monitor, we had this discussion already on this ML.
> Photos require an excellent screen, notbooks are no good in general.


In my office i always use ATI card. Pro-drivers are better quality than
NVidia, especially to use OpenGL (with slideshow plugin for ex.)

Gilles
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