konqy preloading kills performance

[Lubos Lunak]

On Monday 13 of December 2004 19:24, Alexander Neundorf wrote:
> Hi,
>
> I am running KDE 3.2 on a PIII/450 MHz with 128 MB RAM.
> Keeping konqy instances preloaded kills the performance on this box.
> Reason: if I have a konqy with several tabs and visited a bunch of pages,
> konqy grows to more than 50 MB in RAM ( or at least quite big), which
> causes the box to swap. Now closing konqy doesn't help, since konqy remains
> alive and doesn't free its memory. So I had to disable the preloading to
> get the box working at reasonable speed again.
> So IMHO preloading konqy slows the system on slow (ok, low memory) systems

 Sorry, but "IMHO" doesn't count when it comes to performance. Do you have 
facts to support your humble opinion?

> down, on fast systems it is already fast. And the preloading adds quite
> some opportunities for bugs (e.g. profiles)

 Apparently nothing is fast enough. And bugs can be fixed. Usually with less 
effort than fixing performance needs.

On Monday 13 of December 2004 19:57, Alexander Neundorf wrote:
> George wrote:
> > > So IMHO preloading konqy slows the system on slow (ok, low memory)
> > > systems down, on fast systems it is already fast. And the preloading
> > > adds quite some opportunities for bugs (e.g. profiles)
> > > So I'd vote for removing the preloading feature again.
> >
> > Why not just disable it in KControl?  
>
> Well, that's what I did finally. No normal user would have known that
> disabling this option will free 50 MB of RAM.

 It won't. Current Konqueror allows at most 16M memory usage increase after 
startup, and that's real complete memory usage, including shared read-only 
memory used by dlopened modules, not just data. At least as far as Linux is 
concerned. For other platforms which support at least mallinfo(), only memory 
used by malloc() is checked, which is an underestimate, but I don't think 
it'd go as high as 50M.

 And people using platforms where only mallinfo() is available, or where even 
that doesn't exist, are free to improve Konqueror's current_memory_usage().

>
> > In any case, is it possible to buy computers with less than 256MB RAM
> > now?
>
> On ebay, yes.
> I mean, it's a feature intended to make things faster, but on a low-memory
> box (well, 128 MB actually isn't that low) it makes the whole system
> slower. I think it is typically for slow systems that they come with not
> too much RAM, and for these systems optimizations are more important than
> for fast systems, but this feature makes slow systems even slower.

 No, it doesn't. Score 1:1, and we have a tie. Or, given that there are no 
facts stated, the score is probably rather 0:0.

> Allan wrote:
> > Sounds like a kernel problem. Preloading shouldn't kill performance much,
> > as soon as konqueror is unused for a while, the kernel will swap it out
> > and it no longer has an impact on the remaining performance of the
> > machine.
>
> Well, as soon as it is swapped in again (because I want to visit a webpage)
> it has an impact again.

 Of course it has an impact. Positive. Or do you think starting new fresh 
Konqueror and initializing it is faster than just loading from swap something 
that is already partially prepared?

 And if you don't have 16M of swap to spare, I think you should blame your 
performance problems on something else.

> So I'd vote for removing the preloading feature again.

 No. But I guess we could discuss the initial value of the checkbox. If there 
are good reasons for doing so.

-- 
Lubos Lunak
KDE developer
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