Originally posted by pixelherodev
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Con Kolivas Fixes Up GUI-Related Stalls In Mesa
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Last edited by raster; 09 May 2020, 04:06 AM.
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Originally posted by puleglot View PostThat's interesting. After patching mesa-20.1.0_rc2, steam and firefox performs much better. Can anybody confirm that?
Update: it's radeonsi + I'm using hardware acceleration in both firefox and steam.
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For what is worths, in the past I encountered regular freezes using BFS + nvidia driver ... Not sure if this is related though, but this situation caused me to avoid BFS and MuQSS since then. I may give a shot one day when they'll be available in mainstream distribution.
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I haven't looked into the rest of the Mesa code so I don't know why this might be so important. But I can guess.
There might be a limited pool of threads. Once all the thread pool is occupied by SCHED_IDLE threads no high priority threads can be added until they clear out.
Or it might be a memory pool. Maybe the idle thread is supposed to clean up unused objects but it isn't running. Then some high priority threads needs an object, but there's no room available until the idle thread cleans out the old ones.
Or any other kind of object. Perhaps the GPU has a limited number of textures or semaphores or something else.
It's almost certainly something similar to garbage collection in Java. Java runs fine without garbage collection. Right up to the point that it runs out of RAM. At that point everything stops until it has finished a full stop-the-world garbage collection cycle. So it is much better for the program performance if it runs a continuous series of small garbage collections at a low priority, but not such a low priority that it runs out of RAM.
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Oh, and I bet why some people see the problem Con found, and other people don't, is the number of CPU threads available.
This latency thing is probably only found on CPUs like a 4c/4t Intel i5 or a 2c i3. I don't see many graphics output programs that use all 8 threads at 100% on an i7. With 8 CPU threads available there should be plenty of room to run a few SCHED_IDLE tasks.
Using Intel i7's, AMD Ryzens and Power9 64 thread CPUs is probably why I've never experienced the Wayland lag problems other people have reported. Mouse cursor freezes? Not for me.
But if I recall correctly Con Kolivas used to do a lot of testing on four core i5s for his scheduler work. Four cores was kind of an ideal point for his BFS.
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Originally posted by Zan Lynx View PostOh, and I bet why some people see the problem Con found, and other people don't, is the number of CPU threads available.
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