Re: Memory usage..

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Re: Memory usage..
by Thiago Macieira on Wednesday 26/Mar/2008, @15:47

If you compare application to application, a simple one, you'll find that it does take less memory. That's what my tests indicated, by counting the marginal memory usage after the desktop libraries was already loaded (using /proc/<PID>/smaps). My testcase was kwrite.

Two things make it VERY hard to say that "KDE 4 uses less memory than KDE 3":

1) it's not a fair comparison, since the features and services are very different. The experience with KDE 4 is much different from KDE 3. If you really want low memory usage and you're not worried about new features and bugfixes, you can keep using a very old KDE version, or even DOS...

2) it's very difficult to account for memory usage for more than one application. One is easy because you know what is not shared with anyone else. With two or more, you have to ask: what is shared between those applications? And how many pages? We currently don't have the answer for that, but Andrew Morton (kernel developer) mentioned that 2.6.25 will contain a better interface to do just that.

In any case, the 40% figure came from a user that, while well-intentioned, had very little clue about what he was doing. What amazes me is that the press and the public keep referring to those numbers even after we publicly debunked them.

You'll notice that Matthias did not confirm the numbers. He's aware of memory efficiency improvements in Qt 4 and KDE 4 code, but he'll not vouch for a hard number like 40%.

Related Links

·   Articles on Interviews
·   Also by Thiago Macieira
·   Contact author

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Re: Memory usage..
by koos on Wednesday 26/Mar/2008, @18:34

In an addition to the fellow mentioning the extra mem usage of double buffering.
You'll find this in this in the memory of the Xserver not in /proc/<PID>/smaps of the app, as this typically is done using XPixmaps.

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Re: Memory usage..
by Leo S on Wednesday 26/Mar/2008, @22:08

I'm not really complaining about memory usage. More advanced frameworks use more resources. That's just the way things go. But due to double buffering, the same app on Qt4 will use more memory than using Qt3. The process itself might take less, but the cost of double buffering easily erases that small advantage.

And looking at the memory usage of the full desktop running typical apps, it is definitely much more than in KDE3. Like I said, I'm not complaining, but I don't think anyone would seriously argue that it is the case.

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