haggi Posted October 25, 2016 Share Posted October 25, 2016 Hi, with several scenes I have alwas the same problem. I start simulation of a volume or flip sim what works fine for the first few frames. Then the cpu usage drops down and only one core is used most of the time. For every frame, the cpu usage goes up for a few seconds only, then it drops again. So I suppose it has to do something with my general setup. My current simulation is a breaking bottle with liquid what looks like in the attached image. I'd really appreciate if anyone could have a look at the scene and give me a hint what I'm doing wrong. The file is a bit larger (23 mb) so I placed it here: bottle archive Thanks for any ideas. Quote Link to comment Share on other sites More sharing options...
vtrvtr Posted October 25, 2016 Share Posted October 25, 2016 I tested with higher substeps on a mid-end quad-core and it looks fine, ~1min simulatin and CPU usage nothing different (mainly 100%) In general your file seems fine to me Quote Link to comment Share on other sites More sharing options...
dimovfx Posted October 26, 2016 Share Posted October 26, 2016 You can try to turn off "Use Preconditioner" in FLIP Solver. Quote Link to comment Share on other sites More sharing options...
haggi Posted October 26, 2016 Author Share Posted October 26, 2016 Thanks for the tip. Unfortunately it doesn't help. I start a hbatch from the fileCache node and the first 4-5 frames it works fine, then the cpu usage drops down. Every now and then a small peak, but that's all. Turning off the preconditioner doesn't change anything. Maybe it's my machine. I have two cpus with 8 cores each. I'll test to limit the whole thing to fewer cores just for testing. Quote Link to comment Share on other sites More sharing options...
art3mis Posted October 26, 2016 Share Posted October 26, 2016 What specific hardware are you running? Quote Link to comment Share on other sites More sharing options...
haggi Posted October 27, 2016 Author Share Posted October 27, 2016 It is a dual Xeon Windows7 machine with 8 real cores each and with 64GB ram. Quote Link to comment Share on other sites More sharing options...
dimovfx Posted October 27, 2016 Share Posted October 27, 2016 I can't remember where, but there was a comparison between windows and linux in houdini simulations. Performance in windows was degrading over time, compared to linux where performance was consistent during the test. I don't know if that's the case, but could be something to look out for. Quote Link to comment Share on other sites More sharing options...
sekow Posted October 27, 2016 Share Posted October 27, 2016 I cant really observe that here. dual 12 core xeons. with a usage of around 50 % (of all 24). I think the slow down comes from that vdb loading out of sops. Did you observe ram peaks? 64 should be enough, but Houdini on windows aint that good with flushing ram, so its does accumulate in time. and if your is full windows starts to swap, and that will result in just a core working. Quote Link to comment Share on other sites More sharing options...
haggi Posted October 27, 2016 Author Share Posted October 27, 2016 Okay, it seems that Houdini 15.5 is the reason for this behaviour. I just tried with 15 and now it works as expected. I'll downlaod a newer version and check if the behaviour has changed. I'm still at version 15.5.480, the current one is 15.5.632. Quote Link to comment Share on other sites More sharing options...
sekow Posted October 27, 2016 Share Posted October 27, 2016 please do and let support know! Quote Link to comment Share on other sites More sharing options...
Atom Posted October 27, 2016 Share Posted October 27, 2016 (edited) So what are the specs for the machine that is running the sim? I just tried you test scene on H15.5 with the excessively high particle density and it used all 8 of my CPUs constantly. I only simmed 6 frames because it takes forever... But maybe your physical RAM is filling up and then you are swapping to the disk after that causing significant slowdown that presents itself to the system a CPU loss. Also, why haven't you enabled OpenCL? That will give you a speed boost but will also use less CPU, the GPU will be taking up some of the slack. In that case the CPU will not be reporting 100% usage. Edited October 27, 2016 by Atom Quote Link to comment Share on other sites More sharing options...
haggi Posted October 27, 2016 Author Share Posted October 27, 2016 The specs are mentioned above. Physical ram is not filling up. I did not use OpenCL because it (following the docs) only has an effect with viscosity turned on. As mentioned, it works very much better with the 15.0 release. I'll check a newer build as soon as possible. Quote Link to comment Share on other sites More sharing options...
haggi Posted October 27, 2016 Author Share Posted October 27, 2016 Okay, I downloaded the newest build and now it works again, all cores are working. Quote Link to comment Share on other sites More sharing options...
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