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by hvz
Mon Jul 01, 2019 3:57 pm
Forum: General discussion
Topic: A Pi Pie Chart
Replies: 112
Views: 11696

Re: A Pi Pie Chart

Here are my Pi 3B vs Pi 4 numbers. I used the same binary, that I compiled with gcc 6.3 on an older image (because I am having huge performance issues with Raspbian Buster and I wanted to investigate those). For some reason, these performance issues don't show up at all in this pichart-test - but t...
by hvz
Fri Jun 28, 2019 9:50 pm
Forum: General discussion
Topic: A Pi Pie Chart
Replies: 112
Views: 11696

Re: A Pi Pie Chart

Also interesting: Has anyone done a 64 bit test? It's too bad that Raspbian is still 32 bit, but there are other images that are 64 bits. On my Pi 3B I saw (on one specific program, and I think we were using different gcc versions too) a 10% increase in performance vs 32 bit. I'll do some tests next...
by hvz
Fri Jun 28, 2019 9:39 pm
Forum: Troubleshooting
Topic: Newer Raspbian versions a lot slower than older ones? [Solved]
Replies: 7
Views: 697

Re: Newer Raspbian versions a lot slower than older ones? [Solved]

Ok, I found out what was wrong. I measured the old and new image speeds by generating, processing and then sending audio to the built-in sound card of the Pi. But I hadn't checked the audio that came out. I didn't think I needed to, since I was using ALSA with big enough buffers. Anyway, when I plug...
by hvz
Fri Jun 28, 2019 10:52 am
Forum: General discussion
Topic: A Pi Pie Chart
Replies: 112
Views: 11696

Re: A Pi Pie Chart

Here are my Pi 3B vs Pi 4 numbers. I used the same binary, that I compiled with gcc 6.3 on an older image (because I am having huge performance issues with Raspbian Buster and I wanted to investigate those). For some reason, these performance issues don't show up at all in this pichart-test - but th...
by hvz
Fri Jun 28, 2019 9:49 am
Forum: Troubleshooting
Topic: Newer Raspbian versions a lot slower than older ones? [Solved]
Replies: 7
Views: 697

Re: Newer Raspbian versions a lot slower than older ones?

I just ran Pichart (openmp) on both OS's on the Pi 3B, and the performance is nearly identical (within 5%). I used the same binary for both, built on the old image (gcc 6.3). So it looks like I'm doing *something* that has become very heavy in the new OS, which isn't covered by these tests. Edit: I ...
by hvz
Fri Jun 28, 2019 8:58 am
Forum: Troubleshooting
Topic: Newer Raspbian versions a lot slower than older ones? [Solved]
Replies: 7
Views: 697

Re: Newer Raspbian versions a lot slower than older ones?

I'll have to look that up. In my code I'm not using a lot of thread synchronization, so I don't think that it's related. In your case, you really need to start by ruling out the effect of gcc, by using the same binary. Assuming that you compile with an older GLIBC on the Pi 3B+ you can probably just...
by hvz
Thu Jun 27, 2019 3:21 pm
Forum: Troubleshooting
Topic: Newer Raspbian versions a lot slower than older ones? [Solved]
Replies: 7
Views: 697

Newer Raspbian versions a lot slower than older ones? [Solved]

I just installed Raspbian Buster to run some performance tests of my own software on my new Pi 4. To my surprise, the performance was nearly identical to that of my older Pi 3 (not even a 3+). So, I put the Buster MicroSD card into my old Pi 3, and it turned out that CPU load of my software doubled ...

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