After upgrading plasma-desktop from 5.10.5 to 5.12.4, starting plasmashell at login takes about 5 minutes of 100% CPU. During this time, the desktop is black and no panel is visible. Everything else in my KDE desktop works, so I can e.g. press Alt-F2 to get a launcher which can start Konsole and Firefox, or press keyboard shortcuts to change virtual desktops in KWin with animations and normal performance. While the plasmashell process is using 100% CPU, "perf top" says almost all of that goes to Mesa: PerfTop: 4992 irqs/sec kernel: 7.4% exact: 0.0% [4000Hz cycles], (all, 2 CPUs) ----------------------------------------------------------------------------------------------------------------- 54.42% i915_dri.so [.] _mesa_unpack_rgba_row 9.61% i915_dri.so [.] fetch_vector4 5.25% i915_dri.so [.] _mesa_execute_program 2.90% i915_dri.so [.] linear_texel_locations 2.70% i915_dri.so [.] store_vector4 1.84% i915_dri.so [.] sample_2d_linear.isra.30 1.78% [kernel] [k] ___bpf_prog_run 1.75% i915_dri.so [.] fetch_texel_lod 1.63% i915_dri.so [.] lerp_rgba_2d 1.62% [kernel] [k] read_hpet 0.86% i915_dri.so [.] fetch_texel_2d_B8G8R8A8_UNORM 0.50% i915_dri.so [.] sample_linear_2d GDB backtraces of the plasmashell process end somewhere deep within Mesa (with the other threads waiting for poll()): Thread 1 (Thread 0x7ffa810cd7c0 (LWP 10927)): #0 _mesa_unorm_to_float (src_bits=<optimized out>, x=<optimized out>) at /var/tmp/portage/media-libs/mesa-18.0.0/work/mesa-18.0.0/src/mesa/main/format_utils.h:57 #1 unpack_float_b8g8r8a8_unorm (dst=0x7ffd84accc40, void_src=0x7ff9c9d0dd4c) at /var/tmp/portage/media-libs/mesa-18.0.0/work/mesa-18.0.0/src/mesa/main/format_unpack.c:154 #2 _mesa_unpack_rgba_row (format=MESA_FORMAT_B8G8R8A8_UNORM, n=<optimized out>, src=<optimized out>, dst=<optimized out>) at /var/tmp/portage/media-libs/mesa-18.0.0/work/mesa-18.0.0/src/mesa/main/format_unpack.c:5364 #3 0x00007ffa56f9600a in sample_2d_linear (samp=samp@entry=0x55b8d1f4a430, img=img@entry=0x55b8d1ebceb0, texcoord=texcoord@entry=0x7ffd84accdf0, rgba=rgba@entry=0x7ffd84accd10, ctx=<optimized out>) at /var/tmp/portage/media-libs/mesa-18.0.0/work/mesa-18.0.0/src/mesa/swrast/s_texfilter.c:1191 #4 0x00007ffa56f961d1 in sample_linear_2d (ctx=<optimized out>, samp=0x55b8d1f4a430, tObj=<optimized out>, n=<optimized out>, texcoords=<optimized out>, lambda=<optimized out>, rgba=0x7ffd84accd10) at /var/tmp/portage/media-libs/mesa-18.0.0/work/mesa-18.0.0/src/mesa/swrast/s_texfilter.c:1399 #5 0x00007ffa56f84ce0 in fetch_texel_lod (ctx=<optimized out>, texcoord=<optimized out>, ---Type <return> to continue, or q <return> to quit--- lambda=<optimized out>, unit=<optimized out>, color=0x7ffd84acce00) at /var/tmp/portage/media-libs/mesa-18.0.0/work/mesa-18.0.0/src/mesa/swrast/s_fragprog.c:92 #6 0x00007ffa56fc9ffc in fetch_texel (color=0x7ffd84acce00, lodBias=0, texcoord=0x7ffd84accdf0, inst=0x55b8d3d327e0, machine=0x55b8d34a51f0, ctx=0x55b8d22f10b0) at /var/tmp/portage/media-libs/mesa-18.0.0/work/mesa-18.0.0/src/mesa/program/prog_execute.c:310 #7 _mesa_execute_program (ctx=ctx@entry=0x55b8d22f10b0, program=program@entry=0x55b8d3d2ef90, machine=machine@entry=0x55b8d34a51f0) at /var/tmp/portage/media-libs/mesa-18.0.0/work/mesa-18.0.0/src/mesa/program/prog_execute.c:1159 #8 0x00007ffa56f84f9f in run_program (start=0, end=<optimized out>, span=0x7ffd84acdcd0, ctx=<optimized out>) at /var/tmp/portage/media-libs/mesa-18.0.0/work/mesa-18.0.0/src/mesa/swrast/s_fragprog.c:215 #9 _swrast_exec_fragment_program (ctx=<optimized out>, span=0x7ffd84acdcd0) at /var/tmp/portage/media-libs/mesa-18.0.0/work/mesa-18.0.0/src/mesa/swrast/s_fragprog.c:272 #10 0x00007ffa56f8b503 in _swrast_write_rgba_span (ctx=ctx@entry=0x55b8d22f10b0, span=span@entry=0x7ffd84acdcd0) at /var/tmp/portage/media-libs/mesa-18.0.0/work/mesa-18.0.0/src/mesa/swrast/s_span.c:1264 #11 0x00007ffa56f9e718 in general_triangle (ctx=0x55b8d22f10b0, v0=<optimized out>, v1=<optimized out>, v2=0x55b8d386b858) at /var/tmp/portage/media-libs/mesa-18.0.0/work/mesa-18.0.0/src/mesa/swrast/s_tritemp.h:824 #12 0x00007ffa56f65867 in _tnl_render_tri_strip_elts (ctx=0x55b8d22f10b0, start=0, count=6, flags=<optimized out>) at /var/tmp/portage/media-libs/mesa-18.0.0/work/mesa-18.0.0/src/mesa/tnl/t_vb_rendertmp.h:234 #13 0x00007ffa56f66238 in run_render (ctx=0x55b8d22f10b0, stage=<optimized out>) at /var/tmp/portage/media-libs/mesa-18.0.0/work/mesa-18.0.0/src/mesa/tnl/t_vb_render.c:323 #14 0x00007ffa56f5c68a in _tnl_run_pipeline (ctx=ctx@entry=0x55b8d22f10b0) at /var/tmp/portage/media-libs/mesa-18.0.0/work/mesa-18.0.0/src/mesa/tnl/t_pipeline.c:241 #15 0x00007ffa570d3058 in intelRunPipeline (ctx=0x55b8d22f10b0) at /var/tmp/portage/media-libs/mesa-18.0.0/work/mesa-18.0.0/src/mesa/drivers/dri/i915/intel_tris.c:1087 #16 0x00007ffa56f5b95d in _tnl_draw_prims (ctx=0x55b8d22f10b0, prim=0x7ffd84acecb0, nr_prims=1, ib=0x7ffd84acec90, index_bounds_valid=<optimized out>, min_index=<optimized out>, max_index=<optimized out>, tfb_vertcount=0x0, stream=0, indirect=0x0) at /var/tmp/portage/media-libs/mesa-18.0.0/work/mesa-18.0.0/src/mesa/tnl/t_draw.c:521 #17 0x00007ffa56f3ffd8 in vbo_validated_drawrangeelements (ctx=ctx@entry=0x55b8d22f10b0, mode=mode@entry=5, index_bounds_valid=index_bounds_valid@entry=0 '\000', start=start@entry=0, end=end@entry=4294967295, count=count@entry=6, type=5123, indices=0x0, basevertex=0, numInstances=1, baseInstance=0) at /var/tmp/portage/media-libs/mesa-18.0.0/work/mesa-18.0.0/src/mesa/vbo/vbo_exec_array.c:925 #18 0x00007ffa56f4074f in vbo_exec_DrawElements (mode=5, count=6, type=5123, indices=0x0) at /var/tmp/portage/media-libs/mesa-18.0.0/work/mesa-18.0.0/src/mesa/vbo/vbo_exec_array.c:1075 #19 0x00007ffa7eafb361 in QSGBatchRenderer::Renderer::renderUnmergedBatch(QSGBatchRenderer::Batch const*) () ---Type <return> to continue, or q <return> to quit--- from /usr/lib64/libQt5Quick.so.5 #20 0x00007ffa7eafbb1f in QSGBatchRenderer::Renderer::renderBatches() () from /usr/lib64/libQt5Quick.so.5 #21 0x00007ffa7eb013c4 in QSGBatchRenderer::Renderer::render() () from /usr/lib64/libQt5Quick.so.5 #22 0x00007ffa7eaf1860 in QSGRenderer::renderScene(QSGBindable const&) () from /usr/lib64/libQt5Quick.so.5 #23 0x00007ffa7eaf1d1b in QSGRenderer::renderScene(unsigned int) () from /usr/lib64/libQt5Quick.so.5 #24 0x00007ffa7eb2c830 in QSGDefaultRenderContext::renderNextFrame(QSGRenderer*, unsigned int) () from /usr/lib64/libQt5Quick.so.5 #25 0x00007ffa7eb8abfe in QQuickWindowPrivate::renderSceneGraph(QSize const&) () from /usr/lib64/libQt5Quick.so.5 #26 0x00007ffa7eb1ec99 in ?? () from /usr/lib64/libQt5Quick.so.5 #27 0x00007ffa7eb1fc7a in ?? () from /usr/lib64/libQt5Quick.so.5 #28 0x00007ffa7b5f9275 in QWindow::event(QEvent*) () from /usr/lib64/libQt5Gui.so.5 #29 0x00007ffa7eb947e5 in QQuickWindow::event(QEvent*) () from /usr/lib64/libQt5Quick.so.5 #30 0x00007ffa7bf8d90c in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib64/libQt5Widgets.so.5 #31 0x00007ffa7bf951c4 in QApplication::notify(QObject*, QEvent*) () from /usr/lib64/libQt5Widgets.so.5 #32 0x00007ffa7b0a2527 in QCoreApplication::notifyInternal2(QObject*, QEvent*) () from /usr/lib64/libQt5Core.so.5 #33 0x00007ffa7b5eeaaf in QGuiApplicationPrivate::processExposeEvent(QWindowSystemInterfacePrivate::ExposeEvent*) () from /usr/lib64/libQt5Gui.so.5 #34 0x00007ffa7b5ef6ed in QGuiApplicationPrivate::processWindowSystemEvent(QWindowSystemInterfacePrivate::WindowSystemEvent*) () from /usr/lib64/libQt5Gui.so.5 #35 0x00007ffa7b5c896b in QWindowSystemInterface::sendWindowSystemEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib64/libQt5Gui.so.5 #36 0x00007ffa6dcec250 in ?? () from /usr/lib64/libQt5XcbQpa.so.5 #37 0x00007ffa755a7577 in g_main_context_dispatch () from /usr/lib64/libglib-2.0.so.0 #38 0x00007ffa755a77e0 in ?? () from /usr/lib64/libglib-2.0.so.0 #39 0x00007ffa755a788c in g_main_context_iteration () from /usr/lib64/libglib-2.0.so.0 #40 0x00007ffa7b0f353f in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib64/libQt5Core.so.5 #41 0x00007ffa7b0a12aa in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib64/libQt5Core.so.5 #42 0x00007ffa7b0a9964 in QCoreApplication::exec() () from /usr/lib64/libQt5Core.so.5 #43 0x000055b8d0b71c9a in ?? () #44 0x00007ffa7a6b8f0a in __libc_start_main () from /lib64/libc.so.6 #45 0x000055b8d0b7203a in _start () (gdb) quit This is Mesa 18.0.0, but downgrading to Mesa 17.2.8 (which worked with plasma-desktop 5.10.5) makes no difference. I wonder if plasmashell suddenly started using OpenGL features which are unavailable on this (quite old) hardware, so Mesa has to emulate them in software? Hardware information: /var/log/Xorg.0.log: [ 5189.955] (II) intel(0): Using Kernel Mode Setting driver: i915, version 1.6.0 20171222 [ 5189.969] (WW) Falling back to old probe method for modesetting [ 5189.970] (--) intel(0): Integrated Graphics Chipset: Intel(R) 945GM [ 5189.970] (--) intel(0): CPU: x86-64, sse2, sse3, ssse3; using a maximum of 2 threads # grep "model name" /proc/cpuinfo model name : Intel(R) Core(TM)2 CPU T7200 @ 2.00GHz model name : Intel(R) Core(TM)2 CPU T7200 @ 2.00GHz $ glxinfo name of display: :0 display: :0 screen: 0 direct rendering: Yes server glx vendor string: SGI server glx version string: 1.4 server glx extensions: GLX_ARB_create_context, GLX_ARB_create_context_profile, GLX_ARB_fbconfig_float, GLX_ARB_framebuffer_sRGB, GLX_ARB_multisample, GLX_EXT_create_context_es2_profile, GLX_EXT_create_context_es_profile, GLX_EXT_fbconfig_packed_float, GLX_EXT_framebuffer_sRGB, GLX_EXT_import_context, GLX_EXT_libglvnd, GLX_EXT_texture_from_pixmap, GLX_EXT_visual_info, GLX_EXT_visual_rating, GLX_INTEL_swap_event, GLX_MESA_copy_sub_buffer, GLX_OML_swap_method, GLX_SGIS_multisample, GLX_SGIX_fbconfig, GLX_SGIX_pbuffer, GLX_SGIX_visual_select_group, GLX_SGI_make_current_read, GLX_SGI_swap_control client glx vendor string: Mesa Project and SGI client glx version string: 1.4 client glx extensions: GLX_ARB_context_flush_control, GLX_ARB_create_context, GLX_ARB_create_context_profile, GLX_ARB_create_context_robustness, GLX_ARB_fbconfig_float, GLX_ARB_framebuffer_sRGB, GLX_ARB_get_proc_address, GLX_ARB_multisample, GLX_EXT_buffer_age, GLX_EXT_create_context_es2_profile, GLX_EXT_create_context_es_profile, GLX_EXT_fbconfig_packed_float, GLX_EXT_framebuffer_sRGB, GLX_EXT_import_context, GLX_EXT_texture_from_pixmap, GLX_EXT_visual_info, GLX_EXT_visual_rating, GLX_INTEL_swap_event, GLX_MESA_copy_sub_buffer, GLX_MESA_multithread_makecurrent, GLX_MESA_query_renderer, GLX_MESA_swap_control, GLX_OML_swap_method, GLX_OML_sync_control, GLX_SGIS_multisample, GLX_SGIX_fbconfig, GLX_SGIX_pbuffer, GLX_SGIX_visual_select_group, GLX_SGI_make_current_read, GLX_SGI_swap_control, GLX_SGI_video_sync GLX version: 1.4 GLX extensions: GLX_ARB_create_context, GLX_ARB_create_context_profile, GLX_ARB_fbconfig_float, GLX_ARB_framebuffer_sRGB, GLX_ARB_get_proc_address, GLX_ARB_multisample, GLX_EXT_create_context_es2_profile, GLX_EXT_create_context_es_profile, GLX_EXT_fbconfig_packed_float, GLX_EXT_framebuffer_sRGB, GLX_EXT_import_context, GLX_EXT_texture_from_pixmap, GLX_EXT_visual_info, GLX_EXT_visual_rating, GLX_INTEL_swap_event, GLX_MESA_copy_sub_buffer, GLX_MESA_multithread_makecurrent, GLX_MESA_query_renderer, GLX_MESA_swap_control, GLX_OML_swap_method, GLX_OML_sync_control, GLX_SGIS_multisample, GLX_SGIX_fbconfig, GLX_SGIX_pbuffer, GLX_SGIX_visual_select_group, GLX_SGI_make_current_read, GLX_SGI_swap_control, GLX_SGI_video_sync Extended renderer info (GLX_MESA_query_renderer): Vendor: Intel Open Source Technology Center (0x8086) Device: Mesa DRI Intel(R) 945GM (0x27a2) Version: 18.0.0 Accelerated: yes Video memory: 192MB Unified memory: yes Preferred profile: compat (0x2) Max core profile version: 0.0 Max compat profile version: 1.4 Max GLES1 profile version: 1.1 Max GLES[23] profile version: 2.0 OpenGL vendor string: Intel Open Source Technology Center OpenGL renderer string: Mesa DRI Intel(R) 945GM OpenGL version string: 1.4 Mesa 18.0.0 OpenGL extensions: GL_3DFX_texture_compression_FXT1, GL_AMD_shader_trinary_minmax, GL_ANGLE_texture_compression_dxt3, GL_ANGLE_texture_compression_dxt5, GL_APPLE_object_purgeable, GL_APPLE_packed_pixels, GL_ARB_ES2_compatibility, GL_ARB_clear_buffer_object, GL_ARB_compressed_texture_pixel_storage, GL_ARB_copy_buffer, GL_ARB_debug_output, GL_ARB_depth_texture, GL_ARB_draw_buffers, GL_ARB_draw_elements_base_vertex, GL_ARB_explicit_attrib_location, GL_ARB_explicit_uniform_location, GL_ARB_fragment_program, GL_ARB_fragment_shader, GL_ARB_framebuffer_object, GL_ARB_get_program_binary, GL_ARB_get_texture_sub_image, GL_ARB_half_float_pixel, GL_ARB_internalformat_query, GL_ARB_invalidate_subdata, GL_ARB_map_buffer_alignment, GL_ARB_map_buffer_range, GL_ARB_multi_bind, GL_ARB_multisample, GL_ARB_multitexture, GL_ARB_pixel_buffer_object, GL_ARB_point_parameters, GL_ARB_point_sprite, GL_ARB_program_interface_query, GL_ARB_provoking_vertex, GL_ARB_robustness, GL_ARB_sampler_objects, GL_ARB_separate_shader_objects, GL_ARB_shader_objects, GL_ARB_shading_language_100, GL_ARB_shadow, GL_ARB_sync, GL_ARB_texture_border_clamp, GL_ARB_texture_compression, GL_ARB_texture_cube_map, GL_ARB_texture_env_add, GL_ARB_texture_env_combine, GL_ARB_texture_env_crossbar, GL_ARB_texture_env_dot3, GL_ARB_texture_mirrored_repeat, GL_ARB_texture_non_power_of_two, GL_ARB_texture_rectangle, GL_ARB_texture_storage, GL_ARB_transpose_matrix, GL_ARB_vertex_array_object, GL_ARB_vertex_attrib_binding, GL_ARB_vertex_buffer_object, GL_ARB_vertex_program, GL_ARB_vertex_shader, GL_ARB_window_pos, GL_ATI_blend_equation_separate, GL_ATI_draw_buffers, GL_ATI_separate_stencil, GL_ATI_texture_env_combine3, GL_EXT_abgr, GL_EXT_bgra, GL_EXT_blend_color, GL_EXT_blend_equation_separate, GL_EXT_blend_func_separate, GL_EXT_blend_minmax, GL_EXT_blend_subtract, GL_EXT_compiled_vertex_array, GL_EXT_copy_texture, GL_EXT_draw_range_elements, GL_EXT_fog_coord, GL_EXT_framebuffer_blit, GL_EXT_framebuffer_object, GL_EXT_gpu_program_parameters, GL_EXT_multi_draw_arrays, GL_EXT_packed_depth_stencil, GL_EXT_packed_pixels, GL_EXT_pixel_buffer_object, GL_EXT_point_parameters, GL_EXT_polygon_offset, GL_EXT_provoking_vertex, GL_EXT_rescale_normal, GL_EXT_secondary_color, GL_EXT_separate_specular_color, GL_EXT_shadow_funcs, GL_EXT_stencil_two_side, GL_EXT_stencil_wrap, GL_EXT_subtexture, GL_EXT_texture, GL_EXT_texture3D, GL_EXT_texture_compression_dxt1, GL_EXT_texture_compression_s3tc, GL_EXT_texture_cube_map, GL_EXT_texture_edge_clamp, GL_EXT_texture_env_add, GL_EXT_texture_env_combine, GL_EXT_texture_env_dot3, GL_EXT_texture_filter_anisotropic, GL_EXT_texture_lod_bias, GL_EXT_texture_object, GL_EXT_texture_rectangle, GL_EXT_texture_sRGB, GL_EXT_texture_sRGB_decode, GL_EXT_vertex_array, GL_IBM_multimode_draw_arrays, GL_IBM_rasterpos_clip, GL_IBM_texture_mirrored_repeat, GL_INGR_blend_func_separate, GL_KHR_context_flush_control, GL_KHR_debug, GL_KHR_no_error, GL_MESA_pack_invert, GL_MESA_window_pos, GL_MESA_ycbcr_texture, GL_NV_blend_square, GL_NV_light_max_exponent, GL_NV_packed_depth_stencil, GL_NV_texgen_reflection, GL_NV_texture_env_combine4, GL_NV_texture_rectangle, GL_OES_EGL_image, GL_OES_read_format, GL_S3_s3tc, GL_SGIS_generate_mipmap, GL_SGIS_texture_border_clamp, GL_SGIS_texture_edge_clamp, GL_SGIS_texture_lod, GL_SUN_multi_draw_arrays OpenGL ES profile version string: OpenGL ES 2.0 Mesa 18.0.0 OpenGL ES profile shading language version string: OpenGL ES GLSL ES 1.0.16 OpenGL ES profile extensions: GL_ANGLE_texture_compression_dxt3, GL_ANGLE_texture_compression_dxt5, GL_APPLE_texture_max_level, GL_EXT_blend_minmax, GL_EXT_discard_framebuffer, GL_EXT_draw_buffers, GL_EXT_draw_elements_base_vertex, GL_EXT_frag_depth, GL_EXT_map_buffer_range, GL_EXT_multi_draw_arrays, GL_EXT_read_format_bgra, GL_EXT_separate_shader_objects, GL_EXT_texture_border_clamp, GL_EXT_texture_compression_dxt1, GL_EXT_texture_filter_anisotropic, GL_EXT_texture_format_BGRA8888, GL_EXT_unpack_subimage, GL_KHR_context_flush_control, GL_KHR_debug, GL_KHR_no_error, GL_NV_draw_buffers, GL_NV_fbo_color_attachments, GL_NV_read_buffer, GL_NV_read_depth, GL_NV_read_depth_stencil, GL_NV_read_stencil, GL_OES_EGL_image, GL_OES_EGL_sync, GL_OES_depth24, GL_OES_depth_texture, GL_OES_draw_elements_base_vertex, GL_OES_element_index_uint, GL_OES_fbo_render_mipmap, GL_OES_get_program_binary, GL_OES_mapbuffer, GL_OES_packed_depth_stencil, GL_OES_required_internalformat, GL_OES_rgb8_rgba8, GL_OES_stencil8, GL_OES_surfaceless_context, GL_OES_texture_3D, GL_OES_texture_border_clamp, GL_OES_texture_npot, GL_OES_vertex_array_object 24 GLX Visuals visual x bf lv rg d st colorbuffer sr ax dp st accumbuffer ms cav id dep cl sp sz l ci b ro r g b a F gb bf th cl r g b a ns b eat ---------------------------------------------------------------------------- 0x020 24 tc 0 32 0 r y . 8 8 8 8 . . 0 24 8 0 0 0 0 0 0 None 0x021 24 dc 0 32 0 r y . 8 8 8 8 . . 0 24 8 0 0 0 0 0 0 None 0x080 24 tc 0 32 0 r y . 8 8 8 8 . . 0 0 0 0 0 0 0 0 0 None 0x081 24 tc 0 32 0 r . . 8 8 8 8 . . 0 0 0 0 0 0 0 0 0 None 0x082 24 tc 0 32 0 r . . 8 8 8 8 . . 0 24 8 0 0 0 0 0 0 None 0x083 24 tc 0 24 0 r y . 8 8 8 0 . . 0 0 0 0 0 0 0 0 0 None 0x084 24 tc 0 24 0 r . . 8 8 8 0 . . 0 0 0 0 0 0 0 0 0 None 0x085 24 tc 0 24 0 r y . 8 8 8 0 . . 0 24 8 0 0 0 0 0 0 None 0x086 24 tc 0 24 0 r . . 8 8 8 0 . . 0 24 8 0 0 0 0 0 0 None 0x087 24 tc 0 32 0 r y . 8 8 8 8 . . 0 24 8 16 16 16 16 0 0 Slow 0x088 24 tc 0 24 0 r y . 8 8 8 0 . . 0 24 8 0 0 0 0 0 0 None 0x089 24 tc 0 24 0 r y . 8 8 8 0 . . 0 24 8 16 16 16 0 0 0 Slow 0x08a 24 dc 0 32 0 r y . 8 8 8 8 . . 0 0 0 0 0 0 0 0 0 None 0x08b 24 dc 0 32 0 r . . 8 8 8 8 . . 0 0 0 0 0 0 0 0 0 None 0x08c 24 dc 0 32 0 r . . 8 8 8 8 . . 0 24 8 0 0 0 0 0 0 None 0x08d 24 dc 0 24 0 r y . 8 8 8 0 . . 0 0 0 0 0 0 0 0 0 None 0x08e 24 dc 0 24 0 r . . 8 8 8 0 . . 0 0 0 0 0 0 0 0 0 None 0x08f 24 dc 0 24 0 r y . 8 8 8 0 . . 0 24 8 0 0 0 0 0 0 None 0x090 24 dc 0 24 0 r . . 8 8 8 0 . . 0 24 8 0 0 0 0 0 0 None 0x091 24 dc 0 32 0 r y . 8 8 8 8 . . 0 24 8 0 0 0 0 0 0 None 0x092 24 dc 0 32 0 r y . 8 8 8 8 . . 0 24 8 16 16 16 16 0 0 Slow 0x093 24 dc 0 24 0 r y . 8 8 8 0 . . 0 24 8 0 0 0 0 0 0 None 0x094 24 dc 0 24 0 r y . 8 8 8 0 . . 0 24 8 16 16 16 0 0 0 Slow 0x05b 32 tc 0 32 0 r y . 8 8 8 8 . . 0 24 8 0 0 0 0 0 0 None 36 GLXFBConfigs: visual x bf lv rg d st colorbuffer sr ax dp st accumbuffer ms cav id dep cl sp sz l ci b ro r g b a F gb bf th cl r g b a ns b eat ---------------------------------------------------------------------------- 0x05c 0 tc 0 16 0 r y . 5 6 5 0 . . 0 0 0 0 0 0 0 0 0 None 0x05d 0 tc 0 16 0 r . . 5 6 5 0 . . 0 0 0 0 0 0 0 0 0 None 0x05e 0 tc 0 16 0 r y . 5 6 5 0 . . 0 16 0 0 0 0 0 0 0 None 0x05f 0 tc 0 16 0 r . . 5 6 5 0 . . 0 16 0 0 0 0 0 0 0 None 0x060 24 tc 0 32 0 r y . 8 8 8 8 . . 0 0 0 0 0 0 0 0 0 None 0x061 24 tc 0 32 0 r . . 8 8 8 8 . . 0 0 0 0 0 0 0 0 0 None 0x062 24 tc 0 32 0 r y . 8 8 8 8 . . 0 24 8 0 0 0 0 0 0 None 0x063 24 tc 0 32 0 r . . 8 8 8 8 . . 0 24 8 0 0 0 0 0 0 None 0x064 24 tc 0 24 0 r y . 8 8 8 0 . . 0 0 0 0 0 0 0 0 0 None 0x065 24 tc 0 24 0 r . . 8 8 8 0 . . 0 0 0 0 0 0 0 0 0 None 0x066 24 tc 0 24 0 r y . 8 8 8 0 . . 0 24 8 0 0 0 0 0 0 None 0x067 24 tc 0 24 0 r . . 8 8 8 0 . . 0 24 8 0 0 0 0 0 0 None 0x068 0 tc 0 16 0 r y . 5 6 5 0 . . 0 16 0 0 0 0 0 0 0 None 0x069 0 tc 0 16 0 r y . 5 6 5 0 . . 0 16 0 16 16 16 0 0 0 Slow 0x06a 32 tc 0 32 0 r y . 8 8 8 8 . . 0 24 8 0 0 0 0 0 0 None 0x06b 24 tc 0 32 0 r y . 8 8 8 8 . . 0 24 8 16 16 16 16 0 0 Slow 0x06c 24 tc 0 24 0 r y . 8 8 8 0 . . 0 24 8 0 0 0 0 0 0 None 0x06d 24 tc 0 24 0 r y . 8 8 8 0 . . 0 24 8 16 16 16 0 0 0 Slow 0x06e 0 dc 0 16 0 r y . 5 6 5 0 . . 0 0 0 0 0 0 0 0 0 None 0x06f 0 dc 0 16 0 r . . 5 6 5 0 . . 0 0 0 0 0 0 0 0 0 None 0x070 0 dc 0 16 0 r y . 5 6 5 0 . . 0 16 0 0 0 0 0 0 0 None 0x071 0 dc 0 16 0 r . . 5 6 5 0 . . 0 16 0 0 0 0 0 0 0 None 0x072 24 dc 0 32 0 r y . 8 8 8 8 . . 0 0 0 0 0 0 0 0 0 None 0x073 24 dc 0 32 0 r . . 8 8 8 8 . . 0 0 0 0 0 0 0 0 0 None 0x074 24 dc 0 32 0 r y . 8 8 8 8 . . 0 24 8 0 0 0 0 0 0 None 0x075 24 dc 0 32 0 r . . 8 8 8 8 . . 0 24 8 0 0 0 0 0 0 None 0x076 24 dc 0 24 0 r y . 8 8 8 0 . . 0 0 0 0 0 0 0 0 0 None 0x077 24 dc 0 24 0 r . . 8 8 8 0 . . 0 0 0 0 0 0 0 0 0 None 0x078 24 dc 0 24 0 r y . 8 8 8 0 . . 0 24 8 0 0 0 0 0 0 None 0x079 24 dc 0 24 0 r . . 8 8 8 0 . . 0 24 8 0 0 0 0 0 0 None 0x07a 0 dc 0 16 0 r y . 5 6 5 0 . . 0 16 0 0 0 0 0 0 0 None 0x07b 0 dc 0 16 0 r y . 5 6 5 0 . . 0 16 0 16 16 16 0 0 0 Slow 0x07c 24 dc 0 32 0 r y . 8 8 8 8 . . 0 24 8 0 0 0 0 0 0 None 0x07d 24 dc 0 32 0 r y . 8 8 8 8 . . 0 24 8 16 16 16 16 0 0 Slow 0x07e 24 dc 0 24 0 r y . 8 8 8 0 . . 0 24 8 0 0 0 0 0 0 None 0x07f 24 dc 0 24 0 r y . 8 8 8 0 . . 0 24 8 16 16 16 0 0 0 Slow
It turns out this happens not only at startup, but while running as well. A few times per hour, the panel stops responding to input, plasmashell takes a whole CPU core and "perf top" shows the same Mesa functions running. After a minute or two, things quiet down and the panel starts responding again.
*** This bug has been marked as a duplicate of bug 384470 ***