Linux phys_constraint performance issues.

[LindenCX]

I'm aware this list is for client issues with steam games/the client. I was referred here by a steam support agent after I posted a support ticket about it.

The linux binaries for srcds seem to have major problems running phys_constraints.

Here's a video: http://www.youtube.com/watch?v=3EM_RGqm9eo

I've avoided posting this here because I have only been able to reproduce this within Garry's Mod.

Below is Garry's constraint module, this issue only occurs with Welds, which are phys_constraints. Every other constraint seems to work flawlessly.

https://github.com/garrynewman/garrysmod/blob/master/garrysmod/lua/includes/modules/constraint.lua#L414-L478

Thank you,

(This is a cross-post from: https://github.com/ValveSoftware/steam-for-linux/issues/2195)

[bdeen-valve]

@rokrox - It sounds like this issue is with Garry's Mod. Garry builds his own version of the Source engine. The right place to report this is with him (like you did). If, when he looks at it, he sees that the issue came from his original source from us, then he'll let us know. Thanks for reporting this!

[LindenCX]

The issue has been fairly well known around the Garry's Mod community since late 2010, Garry has been pretty active in the reports, but it always comes down to the issue being out of his hands.

To my understanding he doesn't have access to vphysics, which is limiting what he can do about an issue like this. The phys_constraint appears to be the issue but it's garry's additional parameters that seem to bring it out on linux, however the core issue doesn't appear to be garry's fault.

We get redirected to valve, and you guys always redirect us back to garry, and the issue always seems to just get stuck in a standstill.

Garry has made multiple responses on the issue, he acknowledges that there's a problem, but insists that it's not on his side.

[azuisleet]

I haven't seen any activity on this issue, but I want to clear up the misunderstanding first. This issue is caused by unoptimized builds of the vphysics/IVP library, which Garry does not build himself. I've documented this in the linked bug report.

This issues does not only affect GMod, only that GMod is the only game to make heavy use of the constraint system, where optimized math ops make a huge difference, regardless of the number of additional simulation iterations.

[jorgenpt]

@rokrox, @azuisleet: Looks like this issue was resolved recently by one of our engineers, independent of the Garry's Mod issue. It should be fixed in an upcoming TF2 release, and Garry should know who to contact in order to get an updated copy - so feel free to let him know.