Felix Miata wrote:
>> I have a computer without SSE3. It runs Fedora just fine. I initially had
>> 1 GiB of RAM in it, I upgraded it to 3 GiB.
>
> I have approximately 40 Fedora installations on 32 bit CPUs. About half of
> those are on Prescotts. I'm unable to notice that those with more than 1G
> RAM run any better than those with more RAM.
There are mainly 2 reasons I had to upgrade the RAM:
1. Akonadi / KMail 2.
2. "Modern" websites with massive abuse of inline images.
Both of those eat lots and lots of RAM.
> I am able to notice that the older, slower ones that do have SSE2 are able
> to run, but with Plasma 5, those are very slow. Those do run respectably
> with lighter WMs/DEs.
The main limiting factor there is probably not the CPU, but the GPU. If your
GPU does not support OpenGL 2 (OpenGL 1.x is not enough because GLSL shaders
are required), then QML 2 and thus Plasma 5 will fall back to software
rendering through the llvmpipe, which of course on an old CPU is not
impressive speed-wise.
What might help is disabling all the animations that can be disabled.
> For those without SSE2, Plasma 5 is completely unusable, but OK with any
> of the lightweights.
Without SSE2, you additionally also lose the QML/JavaScript JIT in QML 2.
(There is no implementation of the JIT for the 387 FPU instructions, only
for the SSE2 ones.) So you also get an interpreter in C++ there. (At least
there IS a fallback, unlike in V8 and thus Chromium/QtWebEngine.) And of
course the llvmpipe will also be slower without SSE2 instructions. And they
will contend the CPU. There is not much Fedora can do about that, it is a
result of the design choices in upstream Qt.
Kevin Kofler
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