Bug 393706

Due to platform issues, the radeon driver crashes my system daily. As a workaround, so I can get work done, I am stuck using the fbdev Xorg driver.

Everything works great, even 3D games like Jedi Academy are playable (using llvmpipe 3D rendering on ~13 cores), yet for some reason whenever I open a window, KWin eats 100% of a single CPU core for a full 3-4 seconds before drawing the decoration (or allowing any further usage of the GUI). With multiple windows, I have to wait 3-4 seconds *per window* before the system responds again - using Xpra to attach to dozens of windows, I have to just go do something else while I wait.

Compositing is of course disabled.

perf report shows:

Samples: 473K of event 'cycles:ppp', Event count (approx.): 440153905977                                                                                   
Overhead  Command          Shared Object                     Symbol                                                                                        
   2.99%  kwin_x11         libLLVMAnalysis.so.5.0.1          [.] llvm::PointerMayBeCaptured                                                                
   2.06%  kwin_x11         libLLVMCodeGen.so.5.0.1           [.] _init                                                                                     
   1.86%  kwin_x11         libLLVMSelectionDAG.so.5.0.1      [.] _init                                                                                     
   1.83%  kwin_x11         libc-2.25.so                      [.] _int_malloc                                                                               
   1.65%  kwin_x11         libc-2.25.so                      [.] _int_free                                                                                 
   1.61%  kwin_x11         libLLVMCore.so.5.0.1              [.] _init                                                                                     
   1.55%  kwin_x11         libc-2.25.so                      [.] malloc                                                                                    
   1.35%  kwin_x11         libLLVMAnalysis.so.5.0.1          [.] _init                                                                                     
   1.31%  kwin_x11         libLLVMSupport.so.5.0.1           [.] llvm::FoldingSetNodeID::AddInteger                                                        
   1.31%  kwin_x11         libc-2.25.so                      [.] __memcpy_power7                                                                           
   1.02%  kwin_x11         libLLVMSupport.so.5.0.1           [.] llvm::SmallPtrSetImplBase::FindBucketFor                                                  
   0.95%  kwin_x11         libLLVMSupport.so.5.0.1           [.] _init                                                                                     
   0.93%  kwin_x11         swrastg_dri.so                    [.] convert_ubyte_rgba_to_bgra                                                                
   0.72%  kwin_x11         libLLVMCodeGen.so.5.0.1           [.] llvm::LiveIntervalUnion::Query::collectInterferingVRegs                                   
   0.60%  kwin_x11         libLLVMCore.so.5.0.1              [.] llvm::Use::getUser                                                                        
   0.58%  kwin_x11         libLLVMCore.so.5.0.1              [.] llvm::Use::getImpliedUser                                                                 
   0.58%  kwin_x11         libLLVMSelectionDAG.so.5.0.1      [.] llvm::SelectionDAG::computeKnownBits                                                      
   0.57%  kwin_x11         libLLVMSupport.so.5.0.1           [.] llvm::SmallPtrSetImplBase::insert_imp_big                                                 
   0.55%  kwin_x11         libLLVMCore.so.5.0.1              [.] llvm::Type::getPrimitiveSizeInBits                                                        
   0.54%  kwin_x11         libLLVMAnalysis.so.5.0.1          [.] llvm::BasicAAResult::DecomposeGEPExpression