# SyncTrouble on Linux **URL:** https://psychtoolbox.discourse.group/t/synctrouble-on-linux/106 **Category:** Uncategorized **Created:** [April 20, 2017, 12:59pm UTC](https://psychtoolbox.discourse.group/t/synctrouble-on-linux/106 "2017-04-20T12:59:50Z") **Posts on this page:** 2 **Page:** 1
### Author: ![joshshive](https://avatars.discourse-cdn.com/v4/letter/j/c0e974/32.png) [@joshshive](https://psychtoolbox.discourse.group/u/joshshive) #### Post date: [April 20, 2017, 12:59pm UTC](https://psychtoolbox.discourse.group/t/synctrouble-on-linux/106/1 "2017-04-20T12:59:50Z")
Good morning. I'm getting warnings about window 10 not using pageflipping for flip. Here's the trace from DotDemo with Screen('Preference','Verbosity',10) running in Ubuntu 16.04 under XFCE with compositing turned off. I've read through the SyncTrouble documentation for Linux and have tried to implement the various suggestions (e.g., running XOrgConfCreator, making sure triple-buffering is off) but can't seem to solve the problem. Can you provide any suggestions? Thank you for your time, Josh Shive DotDemo RandR: 1366x768 (0x4d)   76.5MHz        h: width  1366 start 1402 end 1450 total 1546 skew    0        v: height  768 start  771 end  776 total  824 PTB-INFO: This is Psychtoolbox-3 for GNU/Linux X11, under GNU/Octave 32-Bit (Version 3.0.14 - Build date: Jan  5 2017). PTB-INFO: Support status on this operating system release: Linux 4.8.0-46-lowlatency Supported. PTB-INFO: Type 'PsychtoolboxVersion' for more detailed version information. PTB-INFO: Most parts of the Psychtoolbox distribution are licensed to you under terms of the MIT License, with PTB-INFO: some restrictions. See file 'License.txt' in the Psychtoolbox root folder for the exact licensing conditions. PTB-DEBUG: Checking PCI device [Intel Corporation 3rd Gen Core processor DRAM Controller] with class x00060000 ... PTB-DEBUG: Checking PCI device [Intel Corporation 3rd Gen Core processor Graphics Controller] with class x00030000 ... PTB-INFO: Skipping detected Intel GPU for safety reasons. setenv('PSYCH\_ALLOW\_DANGEROUS', '1') to override. PTB-DEBUG: Checking PCI device [Intel Corporation 7 Series/C210 Series Chipset Family USB xHCI Host Controller] withclass x000c0330 ... PTB-DEBUG: Checking PCI device [Intel Corporation 7 Series/C210 Series Chipset Family MEI Controller #1] with class x00078000 ... PTB-DEBUG: Checking PCI device [Intel Corporation 7 Series/C210 Series Chipset Family KT Controller] with class x00070002 ... PTB-DEBUG: Checking PCI device [Intel Corporation 82579LM Gigabit Network Connection] with class x00020000 ... PTB-DEBUG: Checking PCI device [Intel Corporation 7 Series/C210 Series Chipset Family USB Enhanced Host Controller #2] with class x000c0320 ... PTB-DEBUG: Checking PCI device [Intel Corporation 7 Series/C210 Series Chipset Family High Definition Audio Controller] with class x00040300 ... PTB-DEBUG: Checking PCI device [Intel Corporation 7 Series/C210 Series Chipset Family PCI Express Root Port 1] with class x00060400 ... PTB-DEBUG: Checking PCI device [Intel Corporation 7 Series/C210 Series Chipset Family PCI Express Root Port 2] with class x00060400 ... PTB-DEBUG: Checking PCI device [Intel Corporation 7 Series/C210 Series Chipset Family PCI Express Root Port 3] with class x00060400 ... PTB-DEBUG: Checking PCI device [Intel Corporation 7 Series/C210 Series Chipset Family PCI Express Root Port 4] with class x00060400 ... PTB-DEBUG: Checking PCI device [Intel Corporation 7 Series/C210 Series Chipset Family PCI Express Root Port 6] with class x00060400 ... PTB-DEBUG: Checking PCI device [Intel Corporation 7 Series/C210 Series Chipset Family USB Enhanced Host Controller #1] with class x000c0320 ... PTB-DEBUG: Checking PCI device [Intel Corporation QM77 Express Chipset LPC Controller] with class x00060100 ... PTB-DEBUG: Checking PCI device [Intel Corporation 82801 Mobile SATA Controller [RAID mode]] with class x00010400 ... PTB-DEBUG: Checking PCI device [Intel Corporation 7 Series/C210 Series Chipset Family SMBus Controller] with class x000c0500 ... PTB-DEBUG: Checking PCI device [Intel Corporation Centrino Advanced-N + WiMAX 6250 [Kilmer Peak]] with class x00028000 ... PTB-DEBUG: Checking PCI device [O2 Micro, Inc. OZ600FJ0/OZ900FJ0/OZ600FJS SD/MMC Card Reader Controller] with class x00080501 ... PTB-INFO: No low-level controllable GPU on screenId 0. Beamposition timestamping and other special functions disabled. PTB-INFO: Using old-style override-redirect setup path for onscreen window creation. PTB-INFO: GLX Visual info depths is 24 bits PTB-INFO: Running on Mesa version 12.0.6 PTB-INFO: This combo of X-Server and Mesa is considered safe for use under DRI3/Present. PTB-INFO: Using GLEW version 2.0.0 for automatic detection of OpenGL extensions... PTB-INFO: Using GLX\_MESA\_swap\_control extension for control of vsync. PTB-INFO: INTEL\_swap\_event support for additional swap completion correctness checks enabled. PTB-DEBUG: PPM file magic is P6 -\> Ok # CREATOR: GIMP PNM Filter Version 1.1 PTB-DEBUG: Recognized splash image of 656 x 304 pixels, maxlevel 255. Loading... OpenGL-Vendor / renderer / version are: Intel Open Source Technology Center - Mesa DRI Intel(R) Ivybridge Mobile x86/MMX/SSE2 - 3.0 Mesa 12.0.6 OpenGL-Extensions are: GL\_ARB\_multisample GL\_EXT\_abgr GL\_EXT\_bgra GL\_EXT\_blend\_color GL\_EXT\_blend\_minmax GL\_EXT\_blend\_subtract GL\_EXT\_copy\_texture GL\_EXT\_polygon\_offset GL\_EXT\_subtexture GL\_EXT\_texture\_object GL\_EXT\_vertex\_array GL\_EXT\_compiled\_vertex\_array GL\_EXT\_texture GL\_EXT\_texture3D GL\_IBM\_rasterpos\_clip GL\_ARB\_point\_parameters GL\_EXT\_draw\_range\_elements GL\_EXT\_packed\_pixels GL\_EXT\_point\_parameters GL\_EXT\_rescale\_normal GL\_EXT\_separate\_specular\_color GL\_EXT\_texture\_edge\_clamp GL\_SGIS\_generate\_mipmap GL\_SGIS\_texture\_border\_clamp GL\_SGIS\_texture\_edge\_clamp GL\_SGIS\_texture\_lod GL\_ARB\_framebuffer\_sRGB GL\_ARB\_multitexture GL\_EXT\_framebuffer\_sRGB GL\_IBM\_multimode\_draw\_arrays GL\_IBM\_texture\_mirrored\_repeat GL\_3DFX\_texture\_compression\_FXT1 GL\_ARB\_texture\_cube\_map GL\_ARB\_texture\_env\_add GL\_ARB\_transpose\_matrixGL\_EXT\_blend\_func\_separate GL\_EXT\_fog\_coord GL\_EXT\_multi\_draw\_arrays GL\_EXT\_secondary\_color GL\_EXT\_texture\_env\_add GL\_EXT\_texture\_filter\_anisotropic GL\_EXT\_texture\_lod\_bias GL\_INGR\_blend\_func\_separate GL\_NV\_blend\_square GL\_NV\_light\_max\_exponent GL\_NV\_texgen\_reflection GL\_NV\_texture\_env\_combine4 GL\_S3\_s3tc GL\_SUN\_multi\_draw\_arrays GL\_ARB\_texture\_border\_clamp GL\_ARB\_texture\_compression GL\_EXT\_framebuffer\_object GL\_EXT\_texture\_compression\_s3tc GL\_EXT\_texture\_env\_combine GL\_EXT\_texture\_env\_dot3 GL\_MESA\_window\_pos GL\_NV\_packed\_depth\_stencil GL\_NV\_texture\_rectangle GL\_ARB\_depth\_texture GL\_ARB\_occlusion\_query GL\_ARB\_shadow GL\_ARB\_texture\_env\_combine GL\_ARB\_texture\_env\_crossbar GL\_ARB\_texture\_env\_dot3 GL\_ARB\_texture\_mirrored\_repeat GL\_ARB\_window\_pos GL\_EXT\_stencil\_two\_side GL\_EXT\_texture\_cube\_map GL\_NV\_depth\_clamp GL\_APPLE\_packed\_pixels GL\_APPLE\_vertex\_array\_object GL\_ARB\_draw\_buffers GL\_ARB\_fragment\_program GL\_ARB\_fragment\_shader GL\_ARB\_shader\_objects GL\_ARB\_vertex\_program GL\_ARB\_vertex\_shader GL\_ATI\_draw\_buffers GL\_ATI\_texture\_env\_combine3 GL\_ATI\_texture\_float GL\_EXT\_shadow\_funcs GL\_EXT\_stencil\_wrap GL\_MESA\_pack\_invert GL\_NV\_primitive\_restart GL\_ARB\_depth\_clamp GL\_ARB\_fragment\_program\_shadow GL\_ARB\_half\_float\_pixel GL\_ARB\_occlusion\_query2 GL\_ARB\_point\_sprite GL\_ARB\_shading\_language\_100 GL\_ARB\_sync GL\_ARB\_texture\_non\_power\_of\_two GL\_ARB\_vertex\_buffer\_object GL\_ATI\_blend\_equation\_separateGL\_EXT\_blend\_equation\_separate GL\_OES\_read\_format GL\_ARB\_color\_buffer\_float GL\_ARB\_pixel\_buffer\_object GL\_ARB\_texture\_compression\_rgtc GL\_ARB\_texture\_float GL\_ARB\_texture\_rectangle GL\_EXT\_packed\_float GL\_EXT\_pixel\_buffer\_object GL\_EXT\_texture\_compression\_dxt1 GL\_EXT\_texture\_compression\_rgtc GL\_EXT\_texture\_rectangle GL\_EXT\_texture\_sRGB GL\_EXT\_texture\_shared\_exponent GL\_ARB\_framebuffer\_object GL\_EXT\_framebuffer\_blit GL\_EXT\_framebuffer\_multisample GL\_EXT\_packed\_depth\_stencil GL\_APPLE\_object\_purgeable GL\_ARB\_vertex\_array\_object GL\_ATI\_separate\_stencil GL\_EXT\_draw\_buffers2 GL\_EXT\_draw\_instanced GL\_EXT\_gpu\_program\_parameters GL\_EXT\_texture\_array GL\_EXT\_texture\_integer GL\_EXT\_texture\_sRGB\_decode GL\_EXT\_timer\_query GL\_OES\_EGL\_image GL\_AMD\_performance\_monitor GL\_ARB\_copy\_buffer GL\_ARB\_depth\_buffer\_float GL\_ARB\_draw\_instanced GL\_ARB\_half\_float\_vertex GL\_ARB\_instanced\_arrays GL\_ARB\_map\_buffer\_range GL\_ARB\_texture\_rg GL\_ARB\_texture\_swizzle GL\_ARB\_vertex\_array\_bgra GL\_EXT\_texture\_swizzle GL\_EXT\_vertex\_array\_bgra GL\_NV\_conditional\_render GL\_AMD\_conservative\_depth GL\_AMD\_draw\_buffers\_blend GL\_AMD\_seamless\_cubemap\_per\_texture GL\_ARB\_ES2\_compatibility GL\_ARB\_blend\_func\_extended GL\_ARB\_debug\_output GL\_ARB\_draw\_buffers\_blend GL\_ARB\_draw\_elements\_base\_vertex GL\_ARB\_explicit\_attrib\_location GL\_ARB\_fragment\_coord\_conventions GL\_ARB\_provoking\_vertex GL\_ARB\_sample\_shading GL\_ARB\_sampler\_objects GL\_ARB\_seamless\_cube\_map GL\_ARB\_shader\_texture\_lod GL\_ARB\_texture\_cube\_map\_array GL\_ARB\_texture\_gather GL\_ARB\_texture\_multisample GL\_ARB\_texture\_query\_lod GL\_ARB\_texture\_rgb10\_a2ui GL\_ARB\_uniform\_buffer\_object GL\_ARB\_vertex\_type\_2\_10\_10\_10\_revGL\_EXT\_provoking\_vertex GL\_EXT\_texture\_snorm GL\_MESA\_texture\_signed\_rgba GL\_NV\_texture\_barrier GL\_ARB\_get\_program\_binary GL\_ARB\_robustness GL\_ARB\_separate\_shader\_objects GL\_ARB\_shader\_bit\_encoding GL\_ARB\_texture\_compression\_bptc GL\_ARB\_timer\_query GL\_ARB\_transform\_feedback2 GL\_ARB\_transform\_feedback3 GL\_ANGLE\_texture\_compression\_dxt3 GL\_ANGLE\_texture\_compression\_dxt5 GL\_ARB\_compressed\_texture\_pixel\_storage GL\_ARB\_conservative\_depth GL\_ARB\_internalformat\_query GL\_ARB\_map\_buffer\_alignment GL\_ARB\_shader\_atomic\_counters GL\_ARB\_shader\_image\_load\_store GL\_ARB\_shading\_language\_420packGL\_ARB\_shading\_language\_packing GL\_ARB\_texture\_storage GL\_ARB\_transform\_feedback\_instanced GL\_EXT\_framebuffer\_multisample\_blit\_scaled GL\_EXT\_transform\_feedback GL\_AMD\_shader\_trinary\_minmax GL\_ARB\_ES3\_compatibility GL\_ARB\_arrays\_of\_arrays GL\_ARB\_clear\_buffer\_object GL\_ARB\_compute\_shader GL\_ARB\_copy\_image GL\_ARB\_explicit\_uniform\_location GL\_ARB\_framebuffer\_no\_attachments GL\_ARB\_invalidate\_subdata GL\_ARB\_program\_interface\_query GL\_ARB\_shader\_image\_size GL\_ARB\_shader\_storage\_buffer\_object GL\_ARB\_texture\_query\_levels GL\_ARB\_texture\_storage\_multisample GL\_ARB\_texture\_view GL\_ARB\_vertex\_attrib\_binding GL\_KHR\_debug GL\_KHR\_robustness GL\_ARB\_buffer\_storage GL\_ARB\_clear\_texture GL\_ARB\_internalformat\_query2 GL\_ARB\_multi\_bind GL\_ARB\_seamless\_cubemap\_per\_texture GL\_ARB\_shader\_draw\_parameters GL\_ARB\_texture\_mirror\_clamp\_to\_edge GL\_ARB\_vertex\_type\_10f\_11f\_11f\_rev GL\_EXT\_shader\_integer\_mix GL\_INTEL\_performance\_query GL\_ARB\_clip\_control GL\_ARB\_conditional\_render\_inverted GL\_ARB\_cull\_distance GL\_ARB\_derivative\_control GL\_ARB\_get\_texture\_sub\_image GL\_ARB\_pipeline\_statistics\_query GL\_ARB\_shader\_texture\_image\_samples GL\_ARB\_texture\_barrier GL\_EXT\_polygon\_offset\_clamp GL\_KHR\_context\_flush\_control GL\_ARB\_shader\_clock GL\_EXT\_shader\_samples\_identical PTB-DEBUG: Linux X11 backend with FOSS drivers - Enabling locked pixeltoken-write + flush workaround for XLib thread-safety. PTB-DEBUG: Interrogating Low-level renderer capabilities for onscreen window with handle 10: Indicator variables: FBO's 1, ATI\_texture\_float 1, ARB\_texture\_float 1, Vendor Intel Open Source Technology Center, Renderer Mesa DRI Intel(R) Ivybridge Mobile x86/MMX/SSE2. Indicator variables: maxcolorattachments = 8, maxrectangletexturesize = 4096, maxnativealuinstructions = 1024. GPU supports non-power-of-two textures. Hardware supports signed normalized textures of 16 bpc integer format. Basic framebuffer objects with rectangle texture rendertargets supported --\> RGBA8 rendertargets with blending. Framebuffer objects support fast blitting between each other. Framebuffer objects support anti-aliasing via multisampling. Framebuffer objects support single-pass multisample resolve blits and image rescaling. Hardware supports floating point textures of 16bpc and 32bpc float format. Assuming HD graphics core or later: Hardware supports full 16/32 bit floating point textures, frame buffers, filtering and blending, as well as some 32 bit float shading. PTB-Info: Running on 'The X.Org Foundation' XServer, Vendor release 11804000. OML\_sync\_control indicators: glXGetSyncValuesOML=0xb3b93b90 , glXWaitForMscOML=0xb3b93d40, glXWaitForSbcOML=0xb3b93e50, glXSwapBuffersMscOML=0xb3b93c00 OML\_sync\_control indicators: glxewIsSupported() says 1. System supports OpenML OML\_sync\_control extension for high-precision scheduled swaps and timestamping. OpenML OML\_sync\_control extension enabled for all scheduled swaps. PTB-DEBUG: Interrogation done. RandR: 1366x768 (0x4d)   76.5MHz        h: width  1366 start 1402 end 1450 total 1546 skew    0        v: height  768 start  771 end  776 total  824 RandR: 1366x768 (0x4d)   76.5MHz        h: width  1366 start 1402 end 1450 total 1546 skew    0        v: height  768 start  771 end  776 total  824 PTB-DEBUG: glClear splash image top-left reference pixel: 255 255 255 PTB-WARNING: Flip for window 10 didn't use pageflipping for flip. Visual presentation timing and timestamps are likely unreliable! PTB-WARNING: Something is misconfigured on your system, otherwise pageflipping would have been used by the graphics driver for reliable timing. PTB-WARNING: Read the Linux specific section of 'help SyncTrouble' for some common causes and fixes for this problem. PTB-DEBUG: Output of all acquired samples of calibration run follows: PTB-DEBUG: Sample 0: 0.000000 PTB-DEBUG: Sample 1: 0.016759 PTB-DEBUG: Sample 2: 0.016760 PTB-DEBUG: Sample 3: 0.016758 PTB-DEBUG: Sample 4: 0.016762 PTB-DEBUG: Sample 5: 0.016758 PTB-DEBUG: Sample 6: 0.016761 PTB-DEBUG: Sample 7: 0.016762 PTB-DEBUG: Sample 8: 0.016754 PTB-DEBUG: Sample 9: 0.016753 PTB-DEBUG: Sample 10: 0.016764 PTB-DEBUG: Sample 11: 0.016758 PTB-DEBUG: Sample 12: 0.016756 PTB-DEBUG: Sample 13: 0.016765 PTB-DEBUG: Sample 14: 0.016754 PTB-DEBUG: Sample 15: 0.016758 PTB-DEBUG: Sample 16: 0.016756 PTB-DEBUG: Sample 17: 0.016765 PTB-DEBUG: Sample 18: 0.016757 PTB-DEBUG: Sample 19: 0.016759 PTB-DEBUG: Sample 20: 0.016752 PTB-DEBUG: Sample 21: 0.016758 PTB-DEBUG: Sample 22: 0.016759 PTB-DEBUG: Sample 23: 0.016760 PTB-DEBUG: Sample 24: 0.016761 PTB-DEBUG: Sample 25: 0.016761 PTB-DEBUG: Sample 26: 0.016753 PTB-DEBUG: Sample 27: 0.016771 PTB-DEBUG: Sample 28: 0.016756 PTB-DEBUG: Sample 29: 0.016757 PTB-DEBUG: Sample 30: 0.016759 PTB-DEBUG: Sample 31: 0.016754 PTB-DEBUG: Sample 32: 0.016766 PTB-DEBUG: Sample 33: 0.016759 PTB-DEBUG: Sample 34: 0.016755 PTB-DEBUG: Sample 35: 0.016755 PTB-DEBUG: Sample 36: 0.016762 PTB-DEBUG: Sample 37: 0.016768 PTB-DEBUG: Sample 38: 0.016756 PTB-DEBUG: Sample 39: 0.016761 PTB-DEBUG: Sample 40: 0.016758 PTB-DEBUG: Sample 41: 0.016754 PTB-DEBUG: Sample 42: 0.016762 PTB-DEBUG: Sample 43: 0.016757 PTB-DEBUG: Sample 44: 0.016761 PTB-DEBUG: Sample 45: 0.016761 PTB-DEBUG: Sample 46: 0.016758 PTB-DEBUG: Sample 47: 0.016755 PTB-DEBUG: Sample 48: 0.016761 PTB-DEBUG: Sample 49: 0.016760 PTB-DEBUG: Sample 50: 0.016755 PTB-DEBUG: End of calibration data for this run... PTB-INFO: OpenGL-Renderer is Intel Open Source Technology Center :: Mesa DRI Intel(R) Ivybridge Mobile x86/MMX/SSE2 :: 3.0 Mesa 12.0.6 PTB-INFO: VBL startline = 768 , VBL Endline = -1 PTB-INFO: Will try to use OS-Builtin OpenML sync control support for accurate Flip timestamping. PTB-INFO: Measured monitor refresh interval from VBLsync = 16.758919 ms [59.669721 Hz]. (50 valid samples taken, stddev=0.003986 ms.) PTB-INFO: Reported monitor refresh interval from operating system = 16.652790 ms [60.049999 Hz]. PTB-INFO: Small deviations between reported values are normal and no reason to worry. PTB-INFO: Support for fast OffscreenWindows enabled. PTB-WARNING: Flip for window 10 didn't use pageflipping for flip. Visual presentation timing and timestamps are likely unreliable! PTB-WARNING: Something is misconfigured on your system, otherwise pageflipping would have been used by the graphics driver for reliable timing. PTB-WARNING: Read the Linux specific section of 'help SyncTrouble' for some common causes and fixes for this problem. PTB-WARNING: Flip for window 10 didn't use pageflipping for flip. Visual presentation timing and timestamps are likely unreliable! PTB-WARNING: Something is misconfigured on your system, otherwise pageflipping would have been used by the graphics driver for reliable timing. PTB-WARNING: Read the Linux specific section of 'help SyncTrouble' for some common causes and fixes for this problem. PTB-WARNING: Flip for window 10 didn't use pageflipping for flip. Visual presentation timing and timestamps are likely unreliable! PTB-WARNING: Something is misconfigured on your system, otherwise pageflipping would have been used by the graphics driver for reliable timing. PTB-WARNING: Read the Linux specific section of 'help SyncTrouble' for some common causes and fixes for this problem. RandR: 1366x768 (0x4d)   76.5MHz        h: width  1366 start 1402 end 1450 total 1546 skew    0        v: height  768 start  771 end  776 total  824 RandR: 1366x768 (0x4d)   76.5MHz        h: width  1366 start 1402 end 1450 total 1546 skew ---
### Author: ![mariokleiner](https://avatars.discourse-cdn.com/v4/letter/m/13edae/32.png) [@mariokleiner](https://psychtoolbox.discourse.group/u/mariokleiner) #### Post date: [April 21, 2017, 2:49pm UTC](https://psychtoolbox.discourse.group/t/synctrouble-on-linux/106/2 "2017-04-21T14:49:29Z")
If you only get this very sporadically, e.g., during startup, then you can basically discount it as a false alert. Maybe i need to update that warning message. In my own experience it happens mostly for a couple of frames during the first run of a script if you have an Intel integrated graphics chip, which doesn't have its own dedicated VRAM, but shares regular system RAM with all other applications and if your memory is pretty full atm., e.g., from running memory intensive tasks beforehand. In that case the graphics driver can't immediately switch to page-flipping because that needs more memory, so while the system frees up the needed memory the driver will fall back to copy swaps and that triggers PTB's warning until the driver can switch to the optimized strategy. If it happens during runtime of the script then (apart from the system running low on memory due to some coding bug of yours, see above) some other application might interfere with stimulus presentation. E.g., you'd get it if in the middle of your session some popup dialog a la "You have new mail" / "System updates available" / "Meeting with John in 10 minutes" would pop up. That's something to take note of, as it would spoil the trial in which it happens. Given that DotDemo runs for thousands of frames, but you only get 4 warnings instead of thousands, i assume it was something temporary like that, so no reason to worry. best, -mario ---In PSYCHTOOLBOX@yahoogroups.com, \ wrote : Good morning. I'm getting warnings about window 10 not using pageflipping for flip. Here's the trace from DotDemo with Screen('Preference','Verbosity',10) running in Ubuntu 16.04 under XFCE with compositing turned off. I've read through the SyncTrouble documentation for Linux and have tried to implement the various suggestions (e.g., running XOrgConfCreator, making sure triple-buffering is off) but can't seem to solve the problem. Can you provide any suggestions? Thank you for your time, Josh Shive DotDemo RandR: 1366x768 (0x4d)   76.5MHz        h: width  1366 start 1402 end 1450 total 1546 skew    0        v: height  768 start  771 end  776 total  824 PTB-INFO: This is Psychtoolbox-3 for GNU/Linux X11, under GNU/Octave 32-Bit (Version 3.0.14 - Build date: Jan  5 2017). PTB-INFO: Support status on this operating system release: Linux 4.8.0-46-lowlatency Supported. PTB-INFO: Type 'PsychtoolboxVersion' for more detailed version information. PTB-INFO: Most parts of the Psychtoolbox distribution are licensed to you under terms of the MIT License, with PTB-INFO: some restrictions. See file 'License.txt' in the Psychtoolbox root folder for the exact licensing conditions. PTB-DEBUG: Checking PCI device [Intel Corporation 3rd Gen Core processor DRAM Controller] with class x00060000 ... PTB-DEBUG: Checking PCI device [Intel Corporation 3rd Gen Core processor Graphics Controller] with class x00030000 ... PTB-INFO: Skipping detected Intel GPU for safety reasons. setenv('PSYCH\_ALLOW\_DANGEROUS', '1') to override. PTB-DEBUG: Checking PCI device [Intel Corporation 7 Series/C210 Series Chipset Family USB xHCI Host Controller] withclass x000c0330 ... PTB-DEBUG: Checking PCI device [Intel Corporation 7 Series/C210 Series Chipset Family MEI Controller #1] with class x00078000 ... PTB-DEBUG: Checking PCI device [Intel Corporation 7 Series/C210 Series Chipset Family KT Controller] with class x00070002 ... PTB-DEBUG: Checking PCI device [Intel Corporation 82579LM Gigabit Network Connection] with class x00020000 ... PTB-DEBUG: Checking PCI device [Intel Corporation 7 Series/C210 Series Chipset Family USB Enhanced Host Controller #2] with class x000c0320 ... PTB-DEBUG: Checking PCI device [Intel Corporation 7 Series/C210 Series Chipset Family High Definition Audio Controller] with class x00040300 ... PTB-DEBUG: Checking PCI device [Intel Corporation 7 Series/C210 Series Chipset Family PCI Express Root Port 1] with class x00060400 ... PTB-DEBUG: Checking PCI device [Intel Corporation 7 Series/C210 Series Chipset Family PCI Express Root Port 2] with class x00060400 ... PTB-DEBUG: Checking PCI device [Intel Corporation 7 Series/C210 Series Chipset Family PCI Express Root Port 3] with class x00060400 ... PTB-DEBUG: Checking PCI device [Intel Corporation 7 Series/C210 Series Chipset Family PCI Express Root Port 4] with class x00060400 ... PTB-DEBUG: Checking PCI device [Intel Corporation 7 Series/C210 Series Chipset Family PCI Express Root Port 6] with class x00060400 ... PTB-DEBUG: Checking PCI device [Intel Corporation 7 Series/C210 Series Chipset Family USB Enhanced Host Controller #1] with class x000c0320 ... PTB-DEBUG: Checking PCI device [Intel Corporation QM77 Express Chipset LPC Controller] with class x00060100 ... PTB-DEBUG: Checking PCI device [Intel Corporation 82801 Mobile SATA Controller [RAID mode]] with class x00010400 ... PTB-DEBUG: Checking PCI device [Intel Corporation 7 Series/C210 Series Chipset Family SMBus Controller] with class x000c0500 ... PTB-DEBUG: Checking PCI device [Intel Corporation Centrino Advanced-N + WiMAX 6250 [Kilmer Peak]] with class x00028000 ... PTB-DEBUG: Checking PCI device [O2 Micro, Inc. OZ600FJ0/OZ900FJ0/OZ600FJS SD/MMC Card Reader Controller] with class x00080501 ... PTB-INFO: No low-level controllable GPU on screenId 0. Beamposition timestamping and other special functions disabled. PTB-INFO: Using old-style override-redirect setup path for onscreen window creation. PTB-INFO: GLX Visual info depths is 24 bits PTB-INFO: Running on Mesa version 12.0.6 PTB-INFO: This combo of X-Server and Mesa is considered safe for use under DRI3/Present. PTB-INFO: Using GLEW version 2.0.0 for automatic detection of OpenGL extensions... PTB-INFO: Using GLX\_MESA\_swap\_control extension for control of vsync. PTB-INFO: INTEL\_swap\_event support for additional swap completion correctness checks enabled. PTB-DEBUG: PPM file magic is P6 -\> Ok # CREATOR: GIMP PNM Filter Version 1.1 PTB-DEBUG: Recognized splash image of 656 x 304 pixels, maxlevel 255. Loading... OpenGL-Vendor / renderer / version are: Intel Open Source Technology Center - Mesa DRI Intel(R) Ivybridge Mobile x86/MMX/SSE2 - 3.0 Mesa 12.0.6 OpenGL-Extensions are: GL\_ARB\_multisample GL\_EXT\_abgr GL\_EXT\_bgra GL\_EXT\_blend\_color GL\_EXT\_blend\_minmax GL\_EXT\_blend\_subtract GL\_EXT\_copy\_texture GL\_EXT\_polygon\_offset GL\_EXT\_subtexture GL\_EXT\_texture\_object GL\_EXT\_vertex\_array GL\_EXT\_compiled\_vertex\_array GL\_EXT\_texture GL\_EXT\_texture3D GL\_IBM\_rasterpos\_clip GL\_ARB\_point\_parameters GL\_EXT\_draw\_range\_elements GL\_EXT\_packed\_pixels GL\_EXT\_point\_parameters GL\_EXT\_rescale\_normal GL\_EXT\_separate\_specular\_color GL\_EXT\_texture\_edge\_clamp GL\_SGIS\_generate\_mipmap GL\_SGIS\_texture\_border\_clamp GL\_SGIS\_texture\_edge\_clamp GL\_SGIS\_texture\_lod GL\_ARB\_framebuffer\_sRGB GL\_ARB\_multitexture GL\_EXT\_framebuffer\_sRGB GL\_IBM\_multimode\_draw\_arrays GL\_IBM\_texture\_mirrored\_repeat GL\_3DFX\_texture\_compression\_FXT1 GL\_ARB\_texture\_cube\_map GL\_ARB\_texture\_env\_add GL\_ARB\_transpose\_matrixGL\_EXT\_blend\_func\_separate GL\_EXT\_fog\_coord GL\_EXT\_multi\_draw\_arrays GL\_EXT\_secondary\_color GL\_EXT\_texture\_env\_add GL\_EXT\_texture\_filter\_anisotropic GL\_EXT\_texture\_lod\_bias GL\_INGR\_blend\_func\_separate GL\_NV\_blend\_square GL\_NV\_light\_max\_exponent GL\_NV\_texgen\_reflection GL\_NV\_texture\_env\_combine4 GL\_S3\_s3tc GL\_SUN\_multi\_draw\_arrays GL\_ARB\_texture\_border\_clamp GL\_ARB\_texture\_compression GL\_EXT\_framebuffer\_object GL\_EXT\_texture\_compression\_s3tc GL\_EXT\_texture\_env\_combine GL\_EXT\_texture\_env\_dot3 GL\_MESA\_window\_pos GL\_NV\_packed\_depth\_stencil GL\_NV\_texture\_rectangle GL\_ARB\_depth\_texture GL\_ARB\_occlusion\_query GL\_ARB\_shadow GL\_ARB\_texture\_env\_combine GL\_ARB\_texture\_env\_crossbar GL\_ARB\_texture\_env\_dot3 GL\_ARB\_texture\_mirrored\_repeat GL\_ARB\_window\_pos GL\_EXT\_stencil\_two\_side GL\_EXT\_texture\_cube\_map GL\_NV\_depth\_clamp GL\_APPLE\_packed\_pixels GL\_APPLE\_vertex\_array\_object GL\_ARB\_draw\_buffers GL\_ARB\_fragment\_program GL\_ARB\_fragment\_shader GL\_ARB\_shader\_objects GL\_ARB\_vertex\_program GL\_ARB\_vertex\_shader GL\_ATI\_draw\_buffers GL\_ATI\_texture\_env\_combine3 GL\_ATI\_texture\_float GL\_EXT\_shadow\_funcs GL\_EXT\_stencil\_wrap GL\_MESA\_pack\_invert GL\_NV\_primitive\_restart GL\_ARB\_depth\_clamp GL\_ARB\_fragment\_program\_shadow GL\_ARB\_half\_float\_pixel GL\_ARB\_occlusion\_query2 GL\_ARB\_point\_sprite GL\_ARB\_shading\_language\_100 GL\_ARB\_sync GL\_ARB\_texture\_non\_power\_of\_two GL\_ARB\_vertex\_buffer\_object GL\_ATI\_blend\_equation\_separateGL\_EXT\_blend\_equation\_separate GL\_OES\_read\_format GL\_ARB\_color\_buffer\_float GL\_ARB\_pixel\_buffer\_object GL\_ARB\_texture\_compression\_rgtc GL\_ARB\_texture\_float GL\_ARB\_texture\_rectangle GL\_EXT\_packed\_float GL\_EXT\_pixel\_buffer\_object GL\_EXT\_texture\_compression\_dxt1 GL\_EXT\_texture\_compression\_rgtc GL\_EXT\_texture\_rectangle GL\_EXT\_texture\_sRGB GL\_EXT\_texture\_shared\_exponent GL\_ARB\_framebuffer\_object GL\_EXT\_framebuffer\_blit GL\_EXT\_framebuffer\_multisample GL\_EXT\_packed\_depth\_stencil GL\_APPLE\_object\_purgeable GL\_ARB\_vertex\_array\_object GL\_ATI\_separate\_stencil GL\_EXT\_draw\_buffers2 GL\_EXT\_draw\_instanced GL\_EXT\_gpu\_program\_parameters GL\_EXT\_texture\_array GL\_EXT\_texture\_integer GL\_EXT\_texture\_sRGB\_decode GL\_EXT\_timer\_query GL\_OES\_EGL\_image GL\_AMD\_performance\_monitor GL\_ARB\_copy\_buffer GL\_ARB\_depth\_buffer\_float GL\_ARB\_draw\_instanced GL\_ARB\_half\_float\_vertex GL\_ARB\_instanced\_arrays GL\_ARB\_map\_buffer\_range GL\_ARB\_texture\_rg GL\_ARB\_texture\_swizzle GL\_ARB\_vertex\_array\_bgra GL\_EXT\_texture\_swizzle GL\_EXT\_vertex\_array\_bgra GL\_NV\_conditional\_render GL\_AMD\_conservative\_depth GL\_AMD\_draw\_buffers\_blend GL\_AMD\_seamless\_cubemap\_per\_texture GL\_ARB\_ES2\_compatibility GL\_ARB\_blend\_func\_extended GL\_ARB\_debug\_output GL\_ARB\_draw\_buffers\_blend GL\_ARB\_draw\_elements\_base\_vertex GL\_ARB\_explicit\_attrib\_location GL\_ARB\_fragment\_coord\_conventions GL\_ARB\_provoking\_vertex GL\_ARB\_sample\_shading GL\_ARB\_sampler\_objects GL\_ARB\_seamless\_cube\_map GL\_ARB\_shader\_texture\_lod GL\_ARB\_texture\_cube\_map\_array GL\_ARB\_texture\_gather GL\_ARB\_texture\_multisample GL\_ARB\_texture\_query\_lod GL\_ARB\_texture\_rgb10\_a2ui GL\_ARB\_uniform\_buffer\_object GL\_ARB\_vertex\_type\_2\_10\_10\_10\_revGL\_EXT\_provoking\_vertex GL\_EXT\_texture\_snorm GL\_MESA\_texture\_signed\_rgba GL\_NV\_texture\_barrier GL\_ARB\_get\_program\_binary GL\_ARB\_robustness GL\_ARB\_separate\_shader\_objects GL\_ARB\_shader\_bit\_encoding GL\_ARB\_texture\_compression\_bptc GL\_ARB\_timer\_query GL\_ARB\_transform\_feedback2 GL\_ARB\_transform\_feedback3 GL\_ANGLE\_texture\_compression\_dxt3 GL\_ANGLE\_texture\_compression\_dxt5 GL\_ARB\_compressed\_texture\_pixel\_storage GL\_ARB\_conservative\_depth GL\_ARB\_internalformat\_query GL\_ARB\_map\_buffer\_alignment GL\_ARB\_shader\_atomic\_counters GL\_ARB\_shader\_image\_load\_store GL\_ARB\_shading\_language\_420packGL\_ARB\_shading\_language\_packing GL\_ARB\_texture\_storage GL\_ARB\_transform\_feedback\_instanced GL\_EXT\_framebuffer\_multisample\_blit\_scaled GL\_EXT\_transform\_feedback GL\_AMD\_shader\_trinary\_minmax GL\_ARB\_ES3\_compatibility GL\_ARB\_arrays\_of\_arrays GL\_ARB\_clear\_buffer\_object GL\_ARB\_compute\_shader GL\_ARB\_copy\_image GL\_ARB\_explicit\_uniform\_location GL\_ARB\_framebuffer\_no\_attachments GL\_ARB\_invalidate\_subdata GL\_ARB\_program\_interface\_query GL\_ARB\_shader\_image\_size GL\_ARB\_shader\_storage\_buffer\_object GL\_ARB\_texture\_query\_levels GL\_ARB\_texture\_storage\_multisample GL\_ARB\_texture\_view GL\_ARB\_vertex\_attrib\_binding GL\_KHR\_debug GL\_KHR\_robustness GL\_ARB\_buffer\_storage GL\_ARB\_clear\_texture GL\_ARB\_internalformat\_query2 GL\_ARB\_multi\_bind GL\_ARB\_seamless\_cubemap\_per\_texture GL\_ARB\_shader\_draw\_parameters GL\_ARB\_texture\_mirror\_clamp\_to\_edge GL\_ARB\_vertex\_type\_10f\_11f\_11f\_rev GL\_EXT\_shader\_integer\_mix GL\_INTEL\_performance\_query GL\_ARB\_clip\_control GL\_ARB\_conditional\_render\_inverted GL\_ARB\_cull\_distance GL\_ARB\_derivative\_control GL\_ARB\_get\_texture\_sub\_image GL\_ARB\_pipeline\_statistics\_query GL\_ARB\_shader\_texture\_image\_samples GL\_ARB\_texture\_barrier GL\_EXT\_polygon\_offset\_clamp GL\_KHR\_context\_flush\_control GL\_ARB\_shader\_clock GL\_EXT\_shader\_samples\_identical PTB-DEBUG: Linux X11 backend with FOSS drivers - Enabling locked pixeltoken-write + flush workaround for XLib thread-safety. PTB-DEBUG: Interrogating Low-level renderer capabilities for onscreen window with handle 10: Indicator variables: FBO's 1, ATI\_texture\_float 1, ARB\_texture\_float 1, Vendor Intel Open Source Technology Center, Renderer Mesa DRI Intel(R) Ivybridge Mobile x86/MMX/SSE2. Indicator variables: maxcolorattachments = 8, maxrectangletexturesize = 4096, maxnativealuinstructions = 1024. GPU supports non-power-of-two textures. Hardware supports signed normalized textures of 16 bpc integer format. Basic framebuffer objects with rectangle texture rendertargets supported --\> RGBA8 rendertargets with blending. Framebuffer objects support fast blitting between each other. Framebuffer objects support anti-aliasing via multisampling. Framebuffer objects support single-pass multisample resolve blits and image rescaling. Hardware supports floating point textures of 16bpc and 32bpc float format. Assuming HD graphics core or later: Hardware supports full 16/32 bit floating point textures, frame buffers, filtering and blending, as well as some 32 bit float shading. PTB-Info: Running on 'The X.Org Foundation' XServer, Vendor release 11804000. OML\_sync\_control indicators: glXGetSyncValuesOML=0xb3b93b90 , glXWaitForMscOML=0xb3b93d40, glXWaitForSbcOML=0xb3b93e50, glXSwapBuffersMscOML=0xb3b93c00 OML\_sync\_control indicators: glxewIsSupported() says 1. System supports OpenML OML\_sync\_control extension for high-precision scheduled swaps and timestamping. OpenML OML\_sync\_control extension enabled for all scheduled swaps. PTB-DEBUG: Interrogation done. RandR: 1366x768 (0x4d)   76.5MHz        h: width  1366 start 1402 end 1450 total 1546 skew    0        v: height  768 start  771 end  776 total  824 RandR: 1366x768 (0x4d)   76.5MHz        h: width  1366 start 1402 end 1450 total 1546 skew    0        v: height  768 start  771 end  776 total  824 PTB-DEBUG: glClear splash image top-left reference pixel: 255 255 255 PTB-WARNING: Flip for window 10 didn't use pageflipping for flip. Visual presentation timing and timestamps are likely unreliable! PTB-WARNING: Something is misconfigured on your system, otherwise pageflipping would have been used by the graphics driver for reliable timing. PTB-WARNING: Read the Linux specific section of 'help SyncTrouble' for some common causes and fixes for this problem. PTB-DEBUG: Output of all acquired samples of calibration run follows: PTB-DEBUG: Sample 0: 0.000000 PTB-DEBUG: Sample 1: 0.016759 PTB-DEBUG: Sample 2: 0.016760 PTB-DEBUG: Sample 3: 0.016758 PTB-DEBUG: Sample 4: 0.016762 PTB-DEBUG: Sample 5: 0.016758 PTB-DEBUG: Sample 6: 0.016761 PTB-DEBUG: Sample 7: 0.016762 PTB-DEBUG: Sample 8: 0.016754 PTB-DEBUG: Sample 9: 0.016753 PTB-DEBUG: Sample 10: 0.016764 PTB-DEBUG: Sample 11: 0.016758 PTB-DEBUG: Sample 12: 0.016756 PTB-DEBUG: Sample 13: 0.016765 PTB-DEBUG: Sample 14: 0.016754 PTB-DEBUG: Sample 15: 0.016758 PTB-DEBUG: Sample 16: 0.016756 PTB-DEBUG: Sample 17: 0.016765 PTB-DEBUG: Sample 18: 0.016757 PTB-DEBUG: Sample 19: 0.016759 PTB-DEBUG: Sample 20: 0.016752 PTB-DEBUG: Sample 21: 0.016758 PTB-DEBUG: Sample 22: 0.016759 PTB-DEBUG: Sample 23: 0.016760 PTB-DEBUG: Sample 24: 0.016761 PTB-DEBUG: Sample 25: 0.016761 PTB-DEBUG: Sample 26: 0.016753 PTB-DEBUG: Sample 27: 0.016771 PTB-DEBUG: Sample 28: 0.016756 PTB-DEBUG: Sample 29: 0.016757 PTB-DEBUG: Sample 30: 0.016759 PTB-DEBUG: Sample 31: 0.016754 PTB-DEBUG: Sample 32: 0.016766 PTB-DEBUG: Sample 33: 0.016759 PTB-DEBUG: Sample 34: 0.016755 PTB-DEBUG: Sample 35: 0.016755 PTB-DEBUG: Sample 36: 0.016762 PTB-DEBUG: Sample 37: 0.016768 PTB-DEBUG: Sample 38: 0.016756 PTB-DEBUG: Sample 39: 0.016761 PTB-DEBUG: Sample 40: 0.016758 PTB-DEBUG: Sample 41: 0.016754 PTB-DEBUG: Sample 42: 0.016762 PTB-DEBUG: Sample 43: 0.016757 PTB-DEBUG: Sample 44: 0.016761 PTB-DEBUG: Sample 45: 0.016761 PTB-DEBUG: Sample 46: 0.016758 PTB-DEBUG: Sample 47: 0.016755 PTB-DEBUG: Sample 48: 0.016761 PTB-DEBUG: Sample 49: 0.016760 PTB-DEBUG: Sample 50: 0.016755 PTB-DEBUG: End of calibration data for this run... PTB-INFO: OpenGL-Renderer is Intel Open Source Technology Center :: Mesa DRI Intel(R) Ivybridge Mobile x86/MMX/SSE2 :: 3.0 Mesa 12.0.6 PTB-INFO: VBL startline = 768 , VBL Endline = -1 PTB-INFO: Will try to use OS-Builtin OpenML sync control support for accurate Flip timestamping. PTB-INFO: Measured monitor refresh interval from VBLsync = 16.758919 ms [59.669721 Hz]. (50 valid samples taken, stddev=0.003986 ms.) PTB-INFO: Reported monitor refresh interval from operating system = 16.652790 ms [60.049999 Hz]. PTB-INFO: Small deviations between reported values are normal and no reason to worry. PTB-INFO: Support for fast OffscreenWindows enabled. PTB-WARNING: Flip for window 10 didn't use pageflipping for flip. Visual presentation timing and timestamps are likely unreliable! PTB-WARNING: Something is misconfigured on your system, otherwise pageflipping would have been used by the graphics driver for reliable timing. PTB-WARNING: Read the Linux specific section of 'help SyncTrouble' for some common causes and fixes for this problem. PTB-WARNING: Flip for window 10 didn't use pageflipping for flip. Visual presentation timing and timestamps are likely unreliable! PTB-WARNING: Something is misconfigured on your system, otherwise pageflipping would have been used by the graphics driver for reliable timing. PTB-WARNING: Read the Linux specific section of 'help SyncTrouble' for some common causes and fixes for this problem. PTB-WARNING: Flip for window 10 didn't use pageflipping for flip. Visual presentation timing and timestamps are likely unreliable! PTB-WARNING: Something is misconfigured on your system, otherwise pageflipping would have been used by the graphics driver for reliable timing. PTB-WARNING: Read the Linux specific section of 'help SyncTrouble' for some common causes and fixes for this problem. RandR: 1366x768 (0x4d)   76.5MHz        h: width  1366 start 1402 end 1450 total 1546 skew    0